Failed emissions test
Guest
Posts: n/a
Re: Failed emissions test
Data Retrieved: http://www.smogtips.com
NOx (Nitrous Oxides) is a chemical created when an engine's combustion
chamber temperatures reach over 2500F. The combination of nitrogen and
oxygen under these high temperatures create NOx. Below are four of the
possibly conditions, that could cause a vehicle to emit an excessive
amount of NOx. Cause #3 is the most common, however in cases were a
vehicle has failed for both high NOx and high HC, pay close attention
to problem #4 also. (Note: You should always insure the EGR is working
fine before replacing the CAT.)
(Rare)1.Bad cooling : If an engine's cooling fans are not turning on
at the right temperature this could cause the engine to overheat and
emit NOx. If your engine doesn't have an over-heating problem you can
omit this problem.
(Rare)2. The second reason for a NOx failure could be high engine
compression. High compression in an engine's combustion chambers
develop over time due to carbon build-up. This high compression causes
high temperatures, which result in NOx emissions. Keep in mind though,
this problem usually is seen in vehicles with over 200,000 miles.
(Most Common)3. The third reason for your NOx failure may be due to a
malfunctioning EGR valve and/or plugged up EGR ports and passages. EGR
stands for exhaust gas recirculation. And that is exactly what this
component does. The EGR system recirculates burned up exhaust gases
back into the combustion chambers. Since these recycled exhaust gases
have already been in the combustion chambers once, they have burned up
most of their fuels, means there is now much less real fuel in the
chambers to ignite. This keeps the chamber temperatures down and thus
reduces NOx emissions. The EGR valve should be inspected to insure its
proper operation. A working valve should be able to open its passage
using manifold vacuum. Manifold vacuum is created during the engine's
intake cycle. The high demand for air during this cycle creates a
vacuum within the engine's intake manifold. This vacuum is then used
to control several important functions within the vehicle, including
controlling the EGR valve. Some vehicles even rely on this vacuum to
control their heating and air-conditioning components. The EGR system
is prone to collecting carbon build-up. Some vehicle manufacturers
recommend cleaning this component an a regular basis.
(Common)4. And, finally, the fourth reason for a NOx failure is a bad
Catalytic Converter. The Catalytic Converter, commonly referred to as
the CAT is a component designed to continue the combustion process
within itself and emit a more thoroughly burned and less harmful
emission containing exhaust. It is normally placed between your
engine's exhaust port and your car's muffler. It allows the engine
exhaust to pass through while it reduces all emissions. A good CAT
should dramatically reduce HC, CO and NOx. The CAT is a catalyst, it
plays a very small part on how well your engine runs. It only begins
working after the exhaust has exited the engines combustion chambers.
And like many catalyst it is not designed to last forever. From time
to time it will need replacement. How long your vehicle's CAT will
last depends on how completely your engine burns the fuel before
presenting it the to the CAT and also on the quality of the CAT.
Factory CATs should normally last 5 to 10 years. Aftermarket CATs
should work for at least half that (for the cost difference I would
normally go with the aftermarket CAT). We see this failure more often
in vehicles which have produced high emission numbers in more then one
category. Note: When replacing your factory CAT it is very important
to use a OEM factory specification replacement part. Not all CATs are
alike. They are all built to suit their own vehicle's specific needs.
The most accurate way to find out if your vehicle CAT is working
efficiently is by using an exhaust gas analyzer. Unfortunately this
tool is fairly expensive and not designed for home use. You must visit
a local smog station and have the smog technician inspect the CAT via
the shop's gas analyzer.
Obvious symptoms of a bad CAT however could be any of the following:
a. major loss of power over 15-25 mph (CAT is plugged up and
restricting exhaust flow)
b. very strong exhaust smell on a vehicle that runs great(engine
running efficiently, but CAT not completing the burning process)
c. Loud rattle being heard from inside the CAT (CAT substrate broken
up).
In this first insure the proper operation of the EGR valve and then
move on to the CAT system. Testing the EGR and CAT systems require
the use of special expert tools. A certified station will be able to
accurately diagnose your vehicle's emissions failure and and help
eliminate the chance of wasting money replacing parts or components
which may have not needed replacement. Specially in the case of
replacing some of the more expensive emission components.
I've found a website on line called http://www.smogtips.com. They have
a lot of information about smog checks and live smog support.
"Christian Fry" <fry_christian@hotmail.com> wrote in message news:<LD62c.5029$i_2.102410@news20.bellglobal.com> ...
> 1988 Jeep Cherokee 4.0
>
> Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> ideas what the problem might be? I changed the plugs, ran some "guaranteed
> to pass" through it, cleaned the air filter, and did the test with the car
> well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> is caused by a cylinder running too hot. Any insight would be great, I'm
> currently car-less!
>
> Regards,
> Chris
NOx (Nitrous Oxides) is a chemical created when an engine's combustion
chamber temperatures reach over 2500F. The combination of nitrogen and
oxygen under these high temperatures create NOx. Below are four of the
possibly conditions, that could cause a vehicle to emit an excessive
amount of NOx. Cause #3 is the most common, however in cases were a
vehicle has failed for both high NOx and high HC, pay close attention
to problem #4 also. (Note: You should always insure the EGR is working
fine before replacing the CAT.)
(Rare)1.Bad cooling : If an engine's cooling fans are not turning on
at the right temperature this could cause the engine to overheat and
emit NOx. If your engine doesn't have an over-heating problem you can
omit this problem.
(Rare)2. The second reason for a NOx failure could be high engine
compression. High compression in an engine's combustion chambers
develop over time due to carbon build-up. This high compression causes
high temperatures, which result in NOx emissions. Keep in mind though,
this problem usually is seen in vehicles with over 200,000 miles.
(Most Common)3. The third reason for your NOx failure may be due to a
malfunctioning EGR valve and/or plugged up EGR ports and passages. EGR
stands for exhaust gas recirculation. And that is exactly what this
component does. The EGR system recirculates burned up exhaust gases
back into the combustion chambers. Since these recycled exhaust gases
have already been in the combustion chambers once, they have burned up
most of their fuels, means there is now much less real fuel in the
chambers to ignite. This keeps the chamber temperatures down and thus
reduces NOx emissions. The EGR valve should be inspected to insure its
proper operation. A working valve should be able to open its passage
using manifold vacuum. Manifold vacuum is created during the engine's
intake cycle. The high demand for air during this cycle creates a
vacuum within the engine's intake manifold. This vacuum is then used
to control several important functions within the vehicle, including
controlling the EGR valve. Some vehicles even rely on this vacuum to
control their heating and air-conditioning components. The EGR system
is prone to collecting carbon build-up. Some vehicle manufacturers
recommend cleaning this component an a regular basis.
(Common)4. And, finally, the fourth reason for a NOx failure is a bad
Catalytic Converter. The Catalytic Converter, commonly referred to as
the CAT is a component designed to continue the combustion process
within itself and emit a more thoroughly burned and less harmful
emission containing exhaust. It is normally placed between your
engine's exhaust port and your car's muffler. It allows the engine
exhaust to pass through while it reduces all emissions. A good CAT
should dramatically reduce HC, CO and NOx. The CAT is a catalyst, it
plays a very small part on how well your engine runs. It only begins
working after the exhaust has exited the engines combustion chambers.
And like many catalyst it is not designed to last forever. From time
to time it will need replacement. How long your vehicle's CAT will
last depends on how completely your engine burns the fuel before
presenting it the to the CAT and also on the quality of the CAT.
Factory CATs should normally last 5 to 10 years. Aftermarket CATs
should work for at least half that (for the cost difference I would
normally go with the aftermarket CAT). We see this failure more often
in vehicles which have produced high emission numbers in more then one
category. Note: When replacing your factory CAT it is very important
to use a OEM factory specification replacement part. Not all CATs are
alike. They are all built to suit their own vehicle's specific needs.
The most accurate way to find out if your vehicle CAT is working
efficiently is by using an exhaust gas analyzer. Unfortunately this
tool is fairly expensive and not designed for home use. You must visit
a local smog station and have the smog technician inspect the CAT via
the shop's gas analyzer.
Obvious symptoms of a bad CAT however could be any of the following:
a. major loss of power over 15-25 mph (CAT is plugged up and
restricting exhaust flow)
b. very strong exhaust smell on a vehicle that runs great(engine
running efficiently, but CAT not completing the burning process)
c. Loud rattle being heard from inside the CAT (CAT substrate broken
up).
In this first insure the proper operation of the EGR valve and then
move on to the CAT system. Testing the EGR and CAT systems require
the use of special expert tools. A certified station will be able to
accurately diagnose your vehicle's emissions failure and and help
eliminate the chance of wasting money replacing parts or components
which may have not needed replacement. Specially in the case of
replacing some of the more expensive emission components.
I've found a website on line called http://www.smogtips.com. They have
a lot of information about smog checks and live smog support.
"Christian Fry" <fry_christian@hotmail.com> wrote in message news:<LD62c.5029$i_2.102410@news20.bellglobal.com> ...
> 1988 Jeep Cherokee 4.0
>
> Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> ideas what the problem might be? I changed the plugs, ran some "guaranteed
> to pass" through it, cleaned the air filter, and did the test with the car
> well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> is caused by a cylinder running too hot. Any insight would be great, I'm
> currently car-less!
>
> Regards,
> Chris
Guest
Posts: n/a
Re: Failed emissions test
Data Retrieved: http://www.smogtips.com
NOx (Nitrous Oxides) is a chemical created when an engine's combustion
chamber temperatures reach over 2500F. The combination of nitrogen and
oxygen under these high temperatures create NOx. Below are four of the
possibly conditions, that could cause a vehicle to emit an excessive
amount of NOx. Cause #3 is the most common, however in cases were a
vehicle has failed for both high NOx and high HC, pay close attention
to problem #4 also. (Note: You should always insure the EGR is working
fine before replacing the CAT.)
(Rare)1.Bad cooling : If an engine's cooling fans are not turning on
at the right temperature this could cause the engine to overheat and
emit NOx. If your engine doesn't have an over-heating problem you can
omit this problem.
(Rare)2. The second reason for a NOx failure could be high engine
compression. High compression in an engine's combustion chambers
develop over time due to carbon build-up. This high compression causes
high temperatures, which result in NOx emissions. Keep in mind though,
this problem usually is seen in vehicles with over 200,000 miles.
(Most Common)3. The third reason for your NOx failure may be due to a
malfunctioning EGR valve and/or plugged up EGR ports and passages. EGR
stands for exhaust gas recirculation. And that is exactly what this
component does. The EGR system recirculates burned up exhaust gases
back into the combustion chambers. Since these recycled exhaust gases
have already been in the combustion chambers once, they have burned up
most of their fuels, means there is now much less real fuel in the
chambers to ignite. This keeps the chamber temperatures down and thus
reduces NOx emissions. The EGR valve should be inspected to insure its
proper operation. A working valve should be able to open its passage
using manifold vacuum. Manifold vacuum is created during the engine's
intake cycle. The high demand for air during this cycle creates a
vacuum within the engine's intake manifold. This vacuum is then used
to control several important functions within the vehicle, including
controlling the EGR valve. Some vehicles even rely on this vacuum to
control their heating and air-conditioning components. The EGR system
is prone to collecting carbon build-up. Some vehicle manufacturers
recommend cleaning this component an a regular basis.
(Common)4. And, finally, the fourth reason for a NOx failure is a bad
Catalytic Converter. The Catalytic Converter, commonly referred to as
the CAT is a component designed to continue the combustion process
within itself and emit a more thoroughly burned and less harmful
emission containing exhaust. It is normally placed between your
engine's exhaust port and your car's muffler. It allows the engine
exhaust to pass through while it reduces all emissions. A good CAT
should dramatically reduce HC, CO and NOx. The CAT is a catalyst, it
plays a very small part on how well your engine runs. It only begins
working after the exhaust has exited the engines combustion chambers.
And like many catalyst it is not designed to last forever. From time
to time it will need replacement. How long your vehicle's CAT will
last depends on how completely your engine burns the fuel before
presenting it the to the CAT and also on the quality of the CAT.
Factory CATs should normally last 5 to 10 years. Aftermarket CATs
should work for at least half that (for the cost difference I would
normally go with the aftermarket CAT). We see this failure more often
in vehicles which have produced high emission numbers in more then one
category. Note: When replacing your factory CAT it is very important
to use a OEM factory specification replacement part. Not all CATs are
alike. They are all built to suit their own vehicle's specific needs.
The most accurate way to find out if your vehicle CAT is working
efficiently is by using an exhaust gas analyzer. Unfortunately this
tool is fairly expensive and not designed for home use. You must visit
a local smog station and have the smog technician inspect the CAT via
the shop's gas analyzer.
Obvious symptoms of a bad CAT however could be any of the following:
a. major loss of power over 15-25 mph (CAT is plugged up and
restricting exhaust flow)
b. very strong exhaust smell on a vehicle that runs great(engine
running efficiently, but CAT not completing the burning process)
c. Loud rattle being heard from inside the CAT (CAT substrate broken
up).
In this first insure the proper operation of the EGR valve and then
move on to the CAT system. Testing the EGR and CAT systems require
the use of special expert tools. A certified station will be able to
accurately diagnose your vehicle's emissions failure and and help
eliminate the chance of wasting money replacing parts or components
which may have not needed replacement. Specially in the case of
replacing some of the more expensive emission components.
I've found a website on line called http://www.smogtips.com. They have
a lot of information about smog checks and live smog support.
"Christian Fry" <fry_christian@hotmail.com> wrote in message news:<LD62c.5029$i_2.102410@news20.bellglobal.com> ...
> 1988 Jeep Cherokee 4.0
>
> Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> ideas what the problem might be? I changed the plugs, ran some "guaranteed
> to pass" through it, cleaned the air filter, and did the test with the car
> well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> is caused by a cylinder running too hot. Any insight would be great, I'm
> currently car-less!
>
> Regards,
> Chris
NOx (Nitrous Oxides) is a chemical created when an engine's combustion
chamber temperatures reach over 2500F. The combination of nitrogen and
oxygen under these high temperatures create NOx. Below are four of the
possibly conditions, that could cause a vehicle to emit an excessive
amount of NOx. Cause #3 is the most common, however in cases were a
vehicle has failed for both high NOx and high HC, pay close attention
to problem #4 also. (Note: You should always insure the EGR is working
fine before replacing the CAT.)
(Rare)1.Bad cooling : If an engine's cooling fans are not turning on
at the right temperature this could cause the engine to overheat and
emit NOx. If your engine doesn't have an over-heating problem you can
omit this problem.
(Rare)2. The second reason for a NOx failure could be high engine
compression. High compression in an engine's combustion chambers
develop over time due to carbon build-up. This high compression causes
high temperatures, which result in NOx emissions. Keep in mind though,
this problem usually is seen in vehicles with over 200,000 miles.
(Most Common)3. The third reason for your NOx failure may be due to a
malfunctioning EGR valve and/or plugged up EGR ports and passages. EGR
stands for exhaust gas recirculation. And that is exactly what this
component does. The EGR system recirculates burned up exhaust gases
back into the combustion chambers. Since these recycled exhaust gases
have already been in the combustion chambers once, they have burned up
most of their fuels, means there is now much less real fuel in the
chambers to ignite. This keeps the chamber temperatures down and thus
reduces NOx emissions. The EGR valve should be inspected to insure its
proper operation. A working valve should be able to open its passage
using manifold vacuum. Manifold vacuum is created during the engine's
intake cycle. The high demand for air during this cycle creates a
vacuum within the engine's intake manifold. This vacuum is then used
to control several important functions within the vehicle, including
controlling the EGR valve. Some vehicles even rely on this vacuum to
control their heating and air-conditioning components. The EGR system
is prone to collecting carbon build-up. Some vehicle manufacturers
recommend cleaning this component an a regular basis.
(Common)4. And, finally, the fourth reason for a NOx failure is a bad
Catalytic Converter. The Catalytic Converter, commonly referred to as
the CAT is a component designed to continue the combustion process
within itself and emit a more thoroughly burned and less harmful
emission containing exhaust. It is normally placed between your
engine's exhaust port and your car's muffler. It allows the engine
exhaust to pass through while it reduces all emissions. A good CAT
should dramatically reduce HC, CO and NOx. The CAT is a catalyst, it
plays a very small part on how well your engine runs. It only begins
working after the exhaust has exited the engines combustion chambers.
And like many catalyst it is not designed to last forever. From time
to time it will need replacement. How long your vehicle's CAT will
last depends on how completely your engine burns the fuel before
presenting it the to the CAT and also on the quality of the CAT.
Factory CATs should normally last 5 to 10 years. Aftermarket CATs
should work for at least half that (for the cost difference I would
normally go with the aftermarket CAT). We see this failure more often
in vehicles which have produced high emission numbers in more then one
category. Note: When replacing your factory CAT it is very important
to use a OEM factory specification replacement part. Not all CATs are
alike. They are all built to suit their own vehicle's specific needs.
The most accurate way to find out if your vehicle CAT is working
efficiently is by using an exhaust gas analyzer. Unfortunately this
tool is fairly expensive and not designed for home use. You must visit
a local smog station and have the smog technician inspect the CAT via
the shop's gas analyzer.
Obvious symptoms of a bad CAT however could be any of the following:
a. major loss of power over 15-25 mph (CAT is plugged up and
restricting exhaust flow)
b. very strong exhaust smell on a vehicle that runs great(engine
running efficiently, but CAT not completing the burning process)
c. Loud rattle being heard from inside the CAT (CAT substrate broken
up).
In this first insure the proper operation of the EGR valve and then
move on to the CAT system. Testing the EGR and CAT systems require
the use of special expert tools. A certified station will be able to
accurately diagnose your vehicle's emissions failure and and help
eliminate the chance of wasting money replacing parts or components
which may have not needed replacement. Specially in the case of
replacing some of the more expensive emission components.
I've found a website on line called http://www.smogtips.com. They have
a lot of information about smog checks and live smog support.
"Christian Fry" <fry_christian@hotmail.com> wrote in message news:<LD62c.5029$i_2.102410@news20.bellglobal.com> ...
> 1988 Jeep Cherokee 4.0
>
> Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> ideas what the problem might be? I changed the plugs, ran some "guaranteed
> to pass" through it, cleaned the air filter, and did the test with the car
> well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> is caused by a cylinder running too hot. Any insight would be great, I'm
> currently car-less!
>
> Regards,
> Chris
Guest
Posts: n/a
Re: Failed emissions test
Data Retrieved: http://www.smogtips.com
NOx (Nitrous Oxides) is a chemical created when an engine's combustion
chamber temperatures reach over 2500F. The combination of nitrogen and
oxygen under these high temperatures create NOx. Below are four of the
possibly conditions, that could cause a vehicle to emit an excessive
amount of NOx. Cause #3 is the most common, however in cases were a
vehicle has failed for both high NOx and high HC, pay close attention
to problem #4 also. (Note: You should always insure the EGR is working
fine before replacing the CAT.)
(Rare)1.Bad cooling : If an engine's cooling fans are not turning on
at the right temperature this could cause the engine to overheat and
emit NOx. If your engine doesn't have an over-heating problem you can
omit this problem.
(Rare)2. The second reason for a NOx failure could be high engine
compression. High compression in an engine's combustion chambers
develop over time due to carbon build-up. This high compression causes
high temperatures, which result in NOx emissions. Keep in mind though,
this problem usually is seen in vehicles with over 200,000 miles.
(Most Common)3. The third reason for your NOx failure may be due to a
malfunctioning EGR valve and/or plugged up EGR ports and passages. EGR
stands for exhaust gas recirculation. And that is exactly what this
component does. The EGR system recirculates burned up exhaust gases
back into the combustion chambers. Since these recycled exhaust gases
have already been in the combustion chambers once, they have burned up
most of their fuels, means there is now much less real fuel in the
chambers to ignite. This keeps the chamber temperatures down and thus
reduces NOx emissions. The EGR valve should be inspected to insure its
proper operation. A working valve should be able to open its passage
using manifold vacuum. Manifold vacuum is created during the engine's
intake cycle. The high demand for air during this cycle creates a
vacuum within the engine's intake manifold. This vacuum is then used
to control several important functions within the vehicle, including
controlling the EGR valve. Some vehicles even rely on this vacuum to
control their heating and air-conditioning components. The EGR system
is prone to collecting carbon build-up. Some vehicle manufacturers
recommend cleaning this component an a regular basis.
(Common)4. And, finally, the fourth reason for a NOx failure is a bad
Catalytic Converter. The Catalytic Converter, commonly referred to as
the CAT is a component designed to continue the combustion process
within itself and emit a more thoroughly burned and less harmful
emission containing exhaust. It is normally placed between your
engine's exhaust port and your car's muffler. It allows the engine
exhaust to pass through while it reduces all emissions. A good CAT
should dramatically reduce HC, CO and NOx. The CAT is a catalyst, it
plays a very small part on how well your engine runs. It only begins
working after the exhaust has exited the engines combustion chambers.
And like many catalyst it is not designed to last forever. From time
to time it will need replacement. How long your vehicle's CAT will
last depends on how completely your engine burns the fuel before
presenting it the to the CAT and also on the quality of the CAT.
Factory CATs should normally last 5 to 10 years. Aftermarket CATs
should work for at least half that (for the cost difference I would
normally go with the aftermarket CAT). We see this failure more often
in vehicles which have produced high emission numbers in more then one
category. Note: When replacing your factory CAT it is very important
to use a OEM factory specification replacement part. Not all CATs are
alike. They are all built to suit their own vehicle's specific needs.
The most accurate way to find out if your vehicle CAT is working
efficiently is by using an exhaust gas analyzer. Unfortunately this
tool is fairly expensive and not designed for home use. You must visit
a local smog station and have the smog technician inspect the CAT via
the shop's gas analyzer.
Obvious symptoms of a bad CAT however could be any of the following:
a. major loss of power over 15-25 mph (CAT is plugged up and
restricting exhaust flow)
b. very strong exhaust smell on a vehicle that runs great(engine
running efficiently, but CAT not completing the burning process)
c. Loud rattle being heard from inside the CAT (CAT substrate broken
up).
In this first insure the proper operation of the EGR valve and then
move on to the CAT system. Testing the EGR and CAT systems require
the use of special expert tools. A certified station will be able to
accurately diagnose your vehicle's emissions failure and and help
eliminate the chance of wasting money replacing parts or components
which may have not needed replacement. Specially in the case of
replacing some of the more expensive emission components.
I've found a website on line called http://www.smogtips.com. They have
a lot of information about smog checks and live smog support.
"Christian Fry" <fry_christian@hotmail.com> wrote in message news:<LD62c.5029$i_2.102410@news20.bellglobal.com> ...
> 1988 Jeep Cherokee 4.0
>
> Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> ideas what the problem might be? I changed the plugs, ran some "guaranteed
> to pass" through it, cleaned the air filter, and did the test with the car
> well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> is caused by a cylinder running too hot. Any insight would be great, I'm
> currently car-less!
>
> Regards,
> Chris
NOx (Nitrous Oxides) is a chemical created when an engine's combustion
chamber temperatures reach over 2500F. The combination of nitrogen and
oxygen under these high temperatures create NOx. Below are four of the
possibly conditions, that could cause a vehicle to emit an excessive
amount of NOx. Cause #3 is the most common, however in cases were a
vehicle has failed for both high NOx and high HC, pay close attention
to problem #4 also. (Note: You should always insure the EGR is working
fine before replacing the CAT.)
(Rare)1.Bad cooling : If an engine's cooling fans are not turning on
at the right temperature this could cause the engine to overheat and
emit NOx. If your engine doesn't have an over-heating problem you can
omit this problem.
(Rare)2. The second reason for a NOx failure could be high engine
compression. High compression in an engine's combustion chambers
develop over time due to carbon build-up. This high compression causes
high temperatures, which result in NOx emissions. Keep in mind though,
this problem usually is seen in vehicles with over 200,000 miles.
(Most Common)3. The third reason for your NOx failure may be due to a
malfunctioning EGR valve and/or plugged up EGR ports and passages. EGR
stands for exhaust gas recirculation. And that is exactly what this
component does. The EGR system recirculates burned up exhaust gases
back into the combustion chambers. Since these recycled exhaust gases
have already been in the combustion chambers once, they have burned up
most of their fuels, means there is now much less real fuel in the
chambers to ignite. This keeps the chamber temperatures down and thus
reduces NOx emissions. The EGR valve should be inspected to insure its
proper operation. A working valve should be able to open its passage
using manifold vacuum. Manifold vacuum is created during the engine's
intake cycle. The high demand for air during this cycle creates a
vacuum within the engine's intake manifold. This vacuum is then used
to control several important functions within the vehicle, including
controlling the EGR valve. Some vehicles even rely on this vacuum to
control their heating and air-conditioning components. The EGR system
is prone to collecting carbon build-up. Some vehicle manufacturers
recommend cleaning this component an a regular basis.
(Common)4. And, finally, the fourth reason for a NOx failure is a bad
Catalytic Converter. The Catalytic Converter, commonly referred to as
the CAT is a component designed to continue the combustion process
within itself and emit a more thoroughly burned and less harmful
emission containing exhaust. It is normally placed between your
engine's exhaust port and your car's muffler. It allows the engine
exhaust to pass through while it reduces all emissions. A good CAT
should dramatically reduce HC, CO and NOx. The CAT is a catalyst, it
plays a very small part on how well your engine runs. It only begins
working after the exhaust has exited the engines combustion chambers.
And like many catalyst it is not designed to last forever. From time
to time it will need replacement. How long your vehicle's CAT will
last depends on how completely your engine burns the fuel before
presenting it the to the CAT and also on the quality of the CAT.
Factory CATs should normally last 5 to 10 years. Aftermarket CATs
should work for at least half that (for the cost difference I would
normally go with the aftermarket CAT). We see this failure more often
in vehicles which have produced high emission numbers in more then one
category. Note: When replacing your factory CAT it is very important
to use a OEM factory specification replacement part. Not all CATs are
alike. They are all built to suit their own vehicle's specific needs.
The most accurate way to find out if your vehicle CAT is working
efficiently is by using an exhaust gas analyzer. Unfortunately this
tool is fairly expensive and not designed for home use. You must visit
a local smog station and have the smog technician inspect the CAT via
the shop's gas analyzer.
Obvious symptoms of a bad CAT however could be any of the following:
a. major loss of power over 15-25 mph (CAT is plugged up and
restricting exhaust flow)
b. very strong exhaust smell on a vehicle that runs great(engine
running efficiently, but CAT not completing the burning process)
c. Loud rattle being heard from inside the CAT (CAT substrate broken
up).
In this first insure the proper operation of the EGR valve and then
move on to the CAT system. Testing the EGR and CAT systems require
the use of special expert tools. A certified station will be able to
accurately diagnose your vehicle's emissions failure and and help
eliminate the chance of wasting money replacing parts or components
which may have not needed replacement. Specially in the case of
replacing some of the more expensive emission components.
I've found a website on line called http://www.smogtips.com. They have
a lot of information about smog checks and live smog support.
"Christian Fry" <fry_christian@hotmail.com> wrote in message news:<LD62c.5029$i_2.102410@news20.bellglobal.com> ...
> 1988 Jeep Cherokee 4.0
>
> Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> ideas what the problem might be? I changed the plugs, ran some "guaranteed
> to pass" through it, cleaned the air filter, and did the test with the car
> well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> is caused by a cylinder running too hot. Any insight would be great, I'm
> currently car-less!
>
> Regards,
> Chris
Guest
Posts: n/a
Re: Failed emissions test
Data Retrieved: http://www.smogtips.com
An Oxygen Sensor can cure a NOx failure if the failure is due to a
Lean Fuel Mixture condition. Lean fuel mixtures cause your engine to
run extra hot. Heat is what causes NOx to be formed.
Fuel distribution to your engine's combustion chambers is controlled
by your vehicle's ECU(Engine Control Unit) and fuel injectors. In
order for your engine to pass a smog inspection, fuel delivery must be
preciously controlled to produce the least emissions. If the injectors
do not present enough fuel to the combustion chambers, this would
cause low CO emissions and high NOx emissions (NOx emissions are
created when the combustion chamber temps reach above 2500F). In a
situation where the injectors present too much fuel, this would causes
high CO emissions and low NOx emissions (Excessive fuel keeps the
chamber temperatures down by cooling the chamber). In order for the
ECU to estimate the right amount of fuel to distribute, it needs to
know how much fuel is currently in the system. This way it can always
maintain a proper ratio and keep emission levels at their lowest. Are
you with me so far? OK. The component responsible for letting the
computer know how much fuel is in the exhaust system at this moment,
is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to
the ECU, letting the computer determine exactly how much fuel it
should continue to deliver to the combustion chambers. If for any
reason the 02 sensor (oxygen sensor) does not send accurate
information to the computer or it is "lazy" in sending the correct
signals, the fuel delivery program can be altered. The computer may
then present either too much or not enough fuel to the combustion
chambers and therefore cause an emission failure.
It may be possible your engine's oxygen sensor is this not sending the
proper signal to the ECU, causing the ECU to send the combustion
chambers less fuel then is necessary to keep the chamber temperature
down, resulting in High NOx and Low CO.
Keep in mind with a computer controlled engine such as this, there are
several other components which also play a role in determining fuel
ratio. Along with the Oxygen Sensor, several components such as the,
TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature
Sensor) and the MAP (Manifold Absolute Pressure Sensor) sensors also
send vital engine information to the computer which is used to
determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service
station would be able to diagnose each component and report it's
condition.
You can find more information on NOx from a website I found recently
called http://www.smogtips.com. They have live e-mail with a smog
tech.
Alec Vega
Mike Romain <romainm@sympatico.ca> wrote in message news:<4048FAAC.779C69C9@sympatico.ca>...
> Our 88 failed too and they figured the EGR solenoid had failed and
> changed it. Plugs, cap and wires got changed too. Same deal another
> fail, so by this time I had enough money in it to get a 2 year
> conditional as it was the first test when the computer wouldn't give the
> conditional!
>
> My 88 4.0 was under recall for a bad O2 sensor. Free new O2 sensor and
> it passed the test. Got my money back from the other tests too, because
> I took it to a Jeep dealer for the test just to avoid silly things and
> they were too lazy to check.
>
> It would be worth calling Chrysler and asking about recalls using your
> VIN.
>
> My recall doesn't show up in the on line databases.
>
> Carbon build up can also make it run hot, the carbon gets cherry and
> spark knock can happen. Any knocking under load?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Christian Fry wrote:
> >
> > 1988 Jeep Cherokee 4.0
> >
> > Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> > ideas what the problem might be? I changed the plugs, ran some "guaranteed
> > to pass" through it, cleaned the air filter, and did the test with the car
> > well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> > is caused by a cylinder running too hot. Any insight would be great, I'm
> > currently car-less!
> >
> > Regards,
> > Chris
An Oxygen Sensor can cure a NOx failure if the failure is due to a
Lean Fuel Mixture condition. Lean fuel mixtures cause your engine to
run extra hot. Heat is what causes NOx to be formed.
Fuel distribution to your engine's combustion chambers is controlled
by your vehicle's ECU(Engine Control Unit) and fuel injectors. In
order for your engine to pass a smog inspection, fuel delivery must be
preciously controlled to produce the least emissions. If the injectors
do not present enough fuel to the combustion chambers, this would
cause low CO emissions and high NOx emissions (NOx emissions are
created when the combustion chamber temps reach above 2500F). In a
situation where the injectors present too much fuel, this would causes
high CO emissions and low NOx emissions (Excessive fuel keeps the
chamber temperatures down by cooling the chamber). In order for the
ECU to estimate the right amount of fuel to distribute, it needs to
know how much fuel is currently in the system. This way it can always
maintain a proper ratio and keep emission levels at their lowest. Are
you with me so far? OK. The component responsible for letting the
computer know how much fuel is in the exhaust system at this moment,
is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to
the ECU, letting the computer determine exactly how much fuel it
should continue to deliver to the combustion chambers. If for any
reason the 02 sensor (oxygen sensor) does not send accurate
information to the computer or it is "lazy" in sending the correct
signals, the fuel delivery program can be altered. The computer may
then present either too much or not enough fuel to the combustion
chambers and therefore cause an emission failure.
It may be possible your engine's oxygen sensor is this not sending the
proper signal to the ECU, causing the ECU to send the combustion
chambers less fuel then is necessary to keep the chamber temperature
down, resulting in High NOx and Low CO.
Keep in mind with a computer controlled engine such as this, there are
several other components which also play a role in determining fuel
ratio. Along with the Oxygen Sensor, several components such as the,
TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature
Sensor) and the MAP (Manifold Absolute Pressure Sensor) sensors also
send vital engine information to the computer which is used to
determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service
station would be able to diagnose each component and report it's
condition.
You can find more information on NOx from a website I found recently
called http://www.smogtips.com. They have live e-mail with a smog
tech.
Alec Vega
Mike Romain <romainm@sympatico.ca> wrote in message news:<4048FAAC.779C69C9@sympatico.ca>...
> Our 88 failed too and they figured the EGR solenoid had failed and
> changed it. Plugs, cap and wires got changed too. Same deal another
> fail, so by this time I had enough money in it to get a 2 year
> conditional as it was the first test when the computer wouldn't give the
> conditional!
>
> My 88 4.0 was under recall for a bad O2 sensor. Free new O2 sensor and
> it passed the test. Got my money back from the other tests too, because
> I took it to a Jeep dealer for the test just to avoid silly things and
> they were too lazy to check.
>
> It would be worth calling Chrysler and asking about recalls using your
> VIN.
>
> My recall doesn't show up in the on line databases.
>
> Carbon build up can also make it run hot, the carbon gets cherry and
> spark knock can happen. Any knocking under load?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Christian Fry wrote:
> >
> > 1988 Jeep Cherokee 4.0
> >
> > Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> > ideas what the problem might be? I changed the plugs, ran some "guaranteed
> > to pass" through it, cleaned the air filter, and did the test with the car
> > well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> > is caused by a cylinder running too hot. Any insight would be great, I'm
> > currently car-less!
> >
> > Regards,
> > Chris
Guest
Posts: n/a
Re: Failed emissions test
Data Retrieved: http://www.smogtips.com
An Oxygen Sensor can cure a NOx failure if the failure is due to a
Lean Fuel Mixture condition. Lean fuel mixtures cause your engine to
run extra hot. Heat is what causes NOx to be formed.
Fuel distribution to your engine's combustion chambers is controlled
by your vehicle's ECU(Engine Control Unit) and fuel injectors. In
order for your engine to pass a smog inspection, fuel delivery must be
preciously controlled to produce the least emissions. If the injectors
do not present enough fuel to the combustion chambers, this would
cause low CO emissions and high NOx emissions (NOx emissions are
created when the combustion chamber temps reach above 2500F). In a
situation where the injectors present too much fuel, this would causes
high CO emissions and low NOx emissions (Excessive fuel keeps the
chamber temperatures down by cooling the chamber). In order for the
ECU to estimate the right amount of fuel to distribute, it needs to
know how much fuel is currently in the system. This way it can always
maintain a proper ratio and keep emission levels at their lowest. Are
you with me so far? OK. The component responsible for letting the
computer know how much fuel is in the exhaust system at this moment,
is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to
the ECU, letting the computer determine exactly how much fuel it
should continue to deliver to the combustion chambers. If for any
reason the 02 sensor (oxygen sensor) does not send accurate
information to the computer or it is "lazy" in sending the correct
signals, the fuel delivery program can be altered. The computer may
then present either too much or not enough fuel to the combustion
chambers and therefore cause an emission failure.
It may be possible your engine's oxygen sensor is this not sending the
proper signal to the ECU, causing the ECU to send the combustion
chambers less fuel then is necessary to keep the chamber temperature
down, resulting in High NOx and Low CO.
Keep in mind with a computer controlled engine such as this, there are
several other components which also play a role in determining fuel
ratio. Along with the Oxygen Sensor, several components such as the,
TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature
Sensor) and the MAP (Manifold Absolute Pressure Sensor) sensors also
send vital engine information to the computer which is used to
determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service
station would be able to diagnose each component and report it's
condition.
You can find more information on NOx from a website I found recently
called http://www.smogtips.com. They have live e-mail with a smog
tech.
Alec Vega
Mike Romain <romainm@sympatico.ca> wrote in message news:<4048FAAC.779C69C9@sympatico.ca>...
> Our 88 failed too and they figured the EGR solenoid had failed and
> changed it. Plugs, cap and wires got changed too. Same deal another
> fail, so by this time I had enough money in it to get a 2 year
> conditional as it was the first test when the computer wouldn't give the
> conditional!
>
> My 88 4.0 was under recall for a bad O2 sensor. Free new O2 sensor and
> it passed the test. Got my money back from the other tests too, because
> I took it to a Jeep dealer for the test just to avoid silly things and
> they were too lazy to check.
>
> It would be worth calling Chrysler and asking about recalls using your
> VIN.
>
> My recall doesn't show up in the on line databases.
>
> Carbon build up can also make it run hot, the carbon gets cherry and
> spark knock can happen. Any knocking under load?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Christian Fry wrote:
> >
> > 1988 Jeep Cherokee 4.0
> >
> > Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> > ideas what the problem might be? I changed the plugs, ran some "guaranteed
> > to pass" through it, cleaned the air filter, and did the test with the car
> > well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> > is caused by a cylinder running too hot. Any insight would be great, I'm
> > currently car-less!
> >
> > Regards,
> > Chris
An Oxygen Sensor can cure a NOx failure if the failure is due to a
Lean Fuel Mixture condition. Lean fuel mixtures cause your engine to
run extra hot. Heat is what causes NOx to be formed.
Fuel distribution to your engine's combustion chambers is controlled
by your vehicle's ECU(Engine Control Unit) and fuel injectors. In
order for your engine to pass a smog inspection, fuel delivery must be
preciously controlled to produce the least emissions. If the injectors
do not present enough fuel to the combustion chambers, this would
cause low CO emissions and high NOx emissions (NOx emissions are
created when the combustion chamber temps reach above 2500F). In a
situation where the injectors present too much fuel, this would causes
high CO emissions and low NOx emissions (Excessive fuel keeps the
chamber temperatures down by cooling the chamber). In order for the
ECU to estimate the right amount of fuel to distribute, it needs to
know how much fuel is currently in the system. This way it can always
maintain a proper ratio and keep emission levels at their lowest. Are
you with me so far? OK. The component responsible for letting the
computer know how much fuel is in the exhaust system at this moment,
is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to
the ECU, letting the computer determine exactly how much fuel it
should continue to deliver to the combustion chambers. If for any
reason the 02 sensor (oxygen sensor) does not send accurate
information to the computer or it is "lazy" in sending the correct
signals, the fuel delivery program can be altered. The computer may
then present either too much or not enough fuel to the combustion
chambers and therefore cause an emission failure.
It may be possible your engine's oxygen sensor is this not sending the
proper signal to the ECU, causing the ECU to send the combustion
chambers less fuel then is necessary to keep the chamber temperature
down, resulting in High NOx and Low CO.
Keep in mind with a computer controlled engine such as this, there are
several other components which also play a role in determining fuel
ratio. Along with the Oxygen Sensor, several components such as the,
TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature
Sensor) and the MAP (Manifold Absolute Pressure Sensor) sensors also
send vital engine information to the computer which is used to
determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service
station would be able to diagnose each component and report it's
condition.
You can find more information on NOx from a website I found recently
called http://www.smogtips.com. They have live e-mail with a smog
tech.
Alec Vega
Mike Romain <romainm@sympatico.ca> wrote in message news:<4048FAAC.779C69C9@sympatico.ca>...
> Our 88 failed too and they figured the EGR solenoid had failed and
> changed it. Plugs, cap and wires got changed too. Same deal another
> fail, so by this time I had enough money in it to get a 2 year
> conditional as it was the first test when the computer wouldn't give the
> conditional!
>
> My 88 4.0 was under recall for a bad O2 sensor. Free new O2 sensor and
> it passed the test. Got my money back from the other tests too, because
> I took it to a Jeep dealer for the test just to avoid silly things and
> they were too lazy to check.
>
> It would be worth calling Chrysler and asking about recalls using your
> VIN.
>
> My recall doesn't show up in the on line databases.
>
> Carbon build up can also make it run hot, the carbon gets cherry and
> spark knock can happen. Any knocking under load?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Christian Fry wrote:
> >
> > 1988 Jeep Cherokee 4.0
> >
> > Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> > ideas what the problem might be? I changed the plugs, ran some "guaranteed
> > to pass" through it, cleaned the air filter, and did the test with the car
> > well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> > is caused by a cylinder running too hot. Any insight would be great, I'm
> > currently car-less!
> >
> > Regards,
> > Chris
Guest
Posts: n/a
Re: Failed emissions test
Data Retrieved: http://www.smogtips.com
An Oxygen Sensor can cure a NOx failure if the failure is due to a
Lean Fuel Mixture condition. Lean fuel mixtures cause your engine to
run extra hot. Heat is what causes NOx to be formed.
Fuel distribution to your engine's combustion chambers is controlled
by your vehicle's ECU(Engine Control Unit) and fuel injectors. In
order for your engine to pass a smog inspection, fuel delivery must be
preciously controlled to produce the least emissions. If the injectors
do not present enough fuel to the combustion chambers, this would
cause low CO emissions and high NOx emissions (NOx emissions are
created when the combustion chamber temps reach above 2500F). In a
situation where the injectors present too much fuel, this would causes
high CO emissions and low NOx emissions (Excessive fuel keeps the
chamber temperatures down by cooling the chamber). In order for the
ECU to estimate the right amount of fuel to distribute, it needs to
know how much fuel is currently in the system. This way it can always
maintain a proper ratio and keep emission levels at their lowest. Are
you with me so far? OK. The component responsible for letting the
computer know how much fuel is in the exhaust system at this moment,
is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to
the ECU, letting the computer determine exactly how much fuel it
should continue to deliver to the combustion chambers. If for any
reason the 02 sensor (oxygen sensor) does not send accurate
information to the computer or it is "lazy" in sending the correct
signals, the fuel delivery program can be altered. The computer may
then present either too much or not enough fuel to the combustion
chambers and therefore cause an emission failure.
It may be possible your engine's oxygen sensor is this not sending the
proper signal to the ECU, causing the ECU to send the combustion
chambers less fuel then is necessary to keep the chamber temperature
down, resulting in High NOx and Low CO.
Keep in mind with a computer controlled engine such as this, there are
several other components which also play a role in determining fuel
ratio. Along with the Oxygen Sensor, several components such as the,
TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature
Sensor) and the MAP (Manifold Absolute Pressure Sensor) sensors also
send vital engine information to the computer which is used to
determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service
station would be able to diagnose each component and report it's
condition.
You can find more information on NOx from a website I found recently
called http://www.smogtips.com. They have live e-mail with a smog
tech.
Alec Vega
Mike Romain <romainm@sympatico.ca> wrote in message news:<4048FAAC.779C69C9@sympatico.ca>...
> Our 88 failed too and they figured the EGR solenoid had failed and
> changed it. Plugs, cap and wires got changed too. Same deal another
> fail, so by this time I had enough money in it to get a 2 year
> conditional as it was the first test when the computer wouldn't give the
> conditional!
>
> My 88 4.0 was under recall for a bad O2 sensor. Free new O2 sensor and
> it passed the test. Got my money back from the other tests too, because
> I took it to a Jeep dealer for the test just to avoid silly things and
> they were too lazy to check.
>
> It would be worth calling Chrysler and asking about recalls using your
> VIN.
>
> My recall doesn't show up in the on line databases.
>
> Carbon build up can also make it run hot, the carbon gets cherry and
> spark knock can happen. Any knocking under load?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Christian Fry wrote:
> >
> > 1988 Jeep Cherokee 4.0
> >
> > Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> > ideas what the problem might be? I changed the plugs, ran some "guaranteed
> > to pass" through it, cleaned the air filter, and did the test with the car
> > well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> > is caused by a cylinder running too hot. Any insight would be great, I'm
> > currently car-less!
> >
> > Regards,
> > Chris
An Oxygen Sensor can cure a NOx failure if the failure is due to a
Lean Fuel Mixture condition. Lean fuel mixtures cause your engine to
run extra hot. Heat is what causes NOx to be formed.
Fuel distribution to your engine's combustion chambers is controlled
by your vehicle's ECU(Engine Control Unit) and fuel injectors. In
order for your engine to pass a smog inspection, fuel delivery must be
preciously controlled to produce the least emissions. If the injectors
do not present enough fuel to the combustion chambers, this would
cause low CO emissions and high NOx emissions (NOx emissions are
created when the combustion chamber temps reach above 2500F). In a
situation where the injectors present too much fuel, this would causes
high CO emissions and low NOx emissions (Excessive fuel keeps the
chamber temperatures down by cooling the chamber). In order for the
ECU to estimate the right amount of fuel to distribute, it needs to
know how much fuel is currently in the system. This way it can always
maintain a proper ratio and keep emission levels at their lowest. Are
you with me so far? OK. The component responsible for letting the
computer know how much fuel is in the exhaust system at this moment,
is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to
the ECU, letting the computer determine exactly how much fuel it
should continue to deliver to the combustion chambers. If for any
reason the 02 sensor (oxygen sensor) does not send accurate
information to the computer or it is "lazy" in sending the correct
signals, the fuel delivery program can be altered. The computer may
then present either too much or not enough fuel to the combustion
chambers and therefore cause an emission failure.
It may be possible your engine's oxygen sensor is this not sending the
proper signal to the ECU, causing the ECU to send the combustion
chambers less fuel then is necessary to keep the chamber temperature
down, resulting in High NOx and Low CO.
Keep in mind with a computer controlled engine such as this, there are
several other components which also play a role in determining fuel
ratio. Along with the Oxygen Sensor, several components such as the,
TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature
Sensor) and the MAP (Manifold Absolute Pressure Sensor) sensors also
send vital engine information to the computer which is used to
determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service
station would be able to diagnose each component and report it's
condition.
You can find more information on NOx from a website I found recently
called http://www.smogtips.com. They have live e-mail with a smog
tech.
Alec Vega
Mike Romain <romainm@sympatico.ca> wrote in message news:<4048FAAC.779C69C9@sympatico.ca>...
> Our 88 failed too and they figured the EGR solenoid had failed and
> changed it. Plugs, cap and wires got changed too. Same deal another
> fail, so by this time I had enough money in it to get a 2 year
> conditional as it was the first test when the computer wouldn't give the
> conditional!
>
> My 88 4.0 was under recall for a bad O2 sensor. Free new O2 sensor and
> it passed the test. Got my money back from the other tests too, because
> I took it to a Jeep dealer for the test just to avoid silly things and
> they were too lazy to check.
>
> It would be worth calling Chrysler and asking about recalls using your
> VIN.
>
> My recall doesn't show up in the on line databases.
>
> Carbon build up can also make it run hot, the carbon gets cherry and
> spark knock can happen. Any knocking under load?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Christian Fry wrote:
> >
> > 1988 Jeep Cherokee 4.0
> >
> > Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> > ideas what the problem might be? I changed the plugs, ran some "guaranteed
> > to pass" through it, cleaned the air filter, and did the test with the car
> > well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> > is caused by a cylinder running too hot. Any insight would be great, I'm
> > currently car-less!
> >
> > Regards,
> > Chris
Guest
Posts: n/a
Re: Failed emissions test
Data Retrieved: http://www.smogtips.com
An Oxygen Sensor can cure a NOx failure if the failure is due to a
Lean Fuel Mixture condition. Lean fuel mixtures cause your engine to
run extra hot. Heat is what causes NOx to be formed.
Fuel distribution to your engine's combustion chambers is controlled
by your vehicle's ECU(Engine Control Unit) and fuel injectors. In
order for your engine to pass a smog inspection, fuel delivery must be
preciously controlled to produce the least emissions. If the injectors
do not present enough fuel to the combustion chambers, this would
cause low CO emissions and high NOx emissions (NOx emissions are
created when the combustion chamber temps reach above 2500F). In a
situation where the injectors present too much fuel, this would causes
high CO emissions and low NOx emissions (Excessive fuel keeps the
chamber temperatures down by cooling the chamber). In order for the
ECU to estimate the right amount of fuel to distribute, it needs to
know how much fuel is currently in the system. This way it can always
maintain a proper ratio and keep emission levels at their lowest. Are
you with me so far? OK. The component responsible for letting the
computer know how much fuel is in the exhaust system at this moment,
is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to
the ECU, letting the computer determine exactly how much fuel it
should continue to deliver to the combustion chambers. If for any
reason the 02 sensor (oxygen sensor) does not send accurate
information to the computer or it is "lazy" in sending the correct
signals, the fuel delivery program can be altered. The computer may
then present either too much or not enough fuel to the combustion
chambers and therefore cause an emission failure.
It may be possible your engine's oxygen sensor is this not sending the
proper signal to the ECU, causing the ECU to send the combustion
chambers less fuel then is necessary to keep the chamber temperature
down, resulting in High NOx and Low CO.
Keep in mind with a computer controlled engine such as this, there are
several other components which also play a role in determining fuel
ratio. Along with the Oxygen Sensor, several components such as the,
TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature
Sensor) and the MAP (Manifold Absolute Pressure Sensor) sensors also
send vital engine information to the computer which is used to
determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service
station would be able to diagnose each component and report it's
condition.
You can find more information on NOx from a website I found recently
called http://www.smogtips.com. They have live e-mail with a smog
tech.
Alec Vega
Mike Romain <romainm@sympatico.ca> wrote in message news:<4048FAAC.779C69C9@sympatico.ca>...
> Our 88 failed too and they figured the EGR solenoid had failed and
> changed it. Plugs, cap and wires got changed too. Same deal another
> fail, so by this time I had enough money in it to get a 2 year
> conditional as it was the first test when the computer wouldn't give the
> conditional!
>
> My 88 4.0 was under recall for a bad O2 sensor. Free new O2 sensor and
> it passed the test. Got my money back from the other tests too, because
> I took it to a Jeep dealer for the test just to avoid silly things and
> they were too lazy to check.
>
> It would be worth calling Chrysler and asking about recalls using your
> VIN.
>
> My recall doesn't show up in the on line databases.
>
> Carbon build up can also make it run hot, the carbon gets cherry and
> spark knock can happen. Any knocking under load?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Christian Fry wrote:
> >
> > 1988 Jeep Cherokee 4.0
> >
> > Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> > ideas what the problem might be? I changed the plugs, ran some "guaranteed
> > to pass" through it, cleaned the air filter, and did the test with the car
> > well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> > is caused by a cylinder running too hot. Any insight would be great, I'm
> > currently car-less!
> >
> > Regards,
> > Chris
An Oxygen Sensor can cure a NOx failure if the failure is due to a
Lean Fuel Mixture condition. Lean fuel mixtures cause your engine to
run extra hot. Heat is what causes NOx to be formed.
Fuel distribution to your engine's combustion chambers is controlled
by your vehicle's ECU(Engine Control Unit) and fuel injectors. In
order for your engine to pass a smog inspection, fuel delivery must be
preciously controlled to produce the least emissions. If the injectors
do not present enough fuel to the combustion chambers, this would
cause low CO emissions and high NOx emissions (NOx emissions are
created when the combustion chamber temps reach above 2500F). In a
situation where the injectors present too much fuel, this would causes
high CO emissions and low NOx emissions (Excessive fuel keeps the
chamber temperatures down by cooling the chamber). In order for the
ECU to estimate the right amount of fuel to distribute, it needs to
know how much fuel is currently in the system. This way it can always
maintain a proper ratio and keep emission levels at their lowest. Are
you with me so far? OK. The component responsible for letting the
computer know how much fuel is in the exhaust system at this moment,
is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to
the ECU, letting the computer determine exactly how much fuel it
should continue to deliver to the combustion chambers. If for any
reason the 02 sensor (oxygen sensor) does not send accurate
information to the computer or it is "lazy" in sending the correct
signals, the fuel delivery program can be altered. The computer may
then present either too much or not enough fuel to the combustion
chambers and therefore cause an emission failure.
It may be possible your engine's oxygen sensor is this not sending the
proper signal to the ECU, causing the ECU to send the combustion
chambers less fuel then is necessary to keep the chamber temperature
down, resulting in High NOx and Low CO.
Keep in mind with a computer controlled engine such as this, there are
several other components which also play a role in determining fuel
ratio. Along with the Oxygen Sensor, several components such as the,
TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature
Sensor) and the MAP (Manifold Absolute Pressure Sensor) sensors also
send vital engine information to the computer which is used to
determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service
station would be able to diagnose each component and report it's
condition.
You can find more information on NOx from a website I found recently
called http://www.smogtips.com. They have live e-mail with a smog
tech.
Alec Vega
Mike Romain <romainm@sympatico.ca> wrote in message news:<4048FAAC.779C69C9@sympatico.ca>...
> Our 88 failed too and they figured the EGR solenoid had failed and
> changed it. Plugs, cap and wires got changed too. Same deal another
> fail, so by this time I had enough money in it to get a 2 year
> conditional as it was the first test when the computer wouldn't give the
> conditional!
>
> My 88 4.0 was under recall for a bad O2 sensor. Free new O2 sensor and
> it passed the test. Got my money back from the other tests too, because
> I took it to a Jeep dealer for the test just to avoid silly things and
> they were too lazy to check.
>
> It would be worth calling Chrysler and asking about recalls using your
> VIN.
>
> My recall doesn't show up in the on line databases.
>
> Carbon build up can also make it run hot, the carbon gets cherry and
> spark knock can happen. Any knocking under load?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Christian Fry wrote:
> >
> > 1988 Jeep Cherokee 4.0
> >
> > Failed the emissions test (grr). The NO PPM was at 1984, max. is 1126. Any
> > ideas what the problem might be? I changed the plugs, ran some "guaranteed
> > to pass" through it, cleaned the air filter, and did the test with the car
> > well warmed up. The guy said if I ran it cold it might pass, as the NO ppm
> > is caused by a cylinder running too hot. Any insight would be great, I'm
> > currently car-less!
> >
> > Regards,
> > Chris
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