Hi all,

I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
with passing emissions inspection in north NJ (Sussex County). The
original results were:

Gas Standard Reading Result
HC 100 27 Pass
CO% 0.50 0.69 Fail
CO2% 13.9
RPM 2668

No figures were given for NOx or O2%.

Okay, no big problem, thinks I. The following parts were replaced:

Oil filter & oil
Air filter
8 Spark plugs
Plug wires (including the distributor/coil wire)
Oxygen Sensor

A mechanic checked the vehicle out, and had a friend of his test
emissions. Despite the vehicle running excellently (no pings, knocks,
stalls, bad starts, dirty exhaust etc.) they could only get the CO%
down to about 0.51 - 0.52.

He tested a load of parts, and reported the following:

1. Fuel pressure test - ok
2. Coolant temp sensor - ok
3. PCV - ok
4. Air filter - new
5. EGR - 100% working ok
6. B-map - ok
7. TPS - ok
8. Injector Balance - ok
9. Plugs, Wires - New
10. Throttle body - cleaned, ok
11. AIS Motor - ok
12. Air control motor - ok

He couldn't figure out what the problem was, but suggested I simply
put it through the test with a gallon of alcohol.

I filled up the gas tank with Mobil Super +, and drove around for a
week to clean the fuel lines through. I filled up again with Mobil
Super +, added a quart of dry gas and a gallon of denatured alcohol
(so I'm guessing the tank would have had about 4% - 5% alcohol), drove
it 15 miles and put it through inspection.

To my amazement, I got the following results:

Gas Standard Reading Result
HC 100 30 Pass
CO% 0.50 0.61 Fail
CO2% 14.1
RPM 2430

I'm like .... WTF????

I've been told the local gas stations are putting additives in the gas
in this area due to the weather, and a lot of cars are losing fuel
consumption and failing emissions inspections. But this is
ridiculous. I can hardly import a tank of gas from Florida, so what
the hell else can I do to get this thing to pass?

Any suggestions gratefully received, short of "move to a state with
less draconian measures".
--
Blue Moon

 

It is really going to come back down to an oxygen sensor problem of some
sort. I have to assume alot to arrive at this, such as the fact that your
mechanic was thorough in checking the O2 sensor operation. The computer is
commanding a fuel mixture based on what it sees as inputs, and if there are
no DTC's, it is probably safe to assume that the computer is happy with what
it sees as the final product: an O2 sensor that toggles from rich to lean
nicely while staying within fuel trim parameters. It is possible, and not
unusual, to get faulty O2 sensors off the shelf. I highly recommend buying
one from the dealer and installing it, so that you know you have a quality
part plugged in.

The catalytic converter is good, as evidenced by the healthy CO2 number.
Winter fuel has it's problems, including a marked decrease in fuel economy,
but it doesn't usually wreck emissions. If it did, all of your neighbors
would be having the same problem.

Start with the air intake, make sure it isn't restricted anywhere (I have
seen mice build nests in the air intake, and also well-intentioned shop
towels that make their way into the air intake tube.). Replace the PCV
valve if you can't remember the last time you did so. If you are equipped
with a multimeter, check the ground side voltage drop from the engine to
battery negative, should be less than .2V. If higher, you have a faulty
ground, and a faulty ground will produce a faulty O2 sensor reading.

Don't spend any more money on ignition components, this is strictly a fuel
mixture problem. Give us updates, so we know what works and what doesn't.

Jerry

"Blue Moon" <mfoco@hotmail.com> wrote in message
news:68b9a6502cd0b4ab8563e8007f3678b8@news.teranew s.com...
> Hi all,
>
> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
> with passing emissions inspection in north NJ (Sussex County). The
> original results were:
>
> Gas Standard Reading Result
> HC 100 27 Pass
> CO% 0.50 0.69 Fail
> CO2% 13.9
> RPM 2668
>
> No figures were given for NOx or O2%.
>
> Okay, no big problem, thinks I. The following parts were replaced:
>
> Oil filter & oil
> Air filter
> 8 Spark plugs
> Plug wires (including the distributor/coil wire)
> Oxygen Sensor
>
> A mechanic checked the vehicle out, and had a friend of his test
> emissions. Despite the vehicle running excellently (no pings, knocks,
> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
> down to about 0.51 - 0.52.
>
> He tested a load of parts, and reported the following:
>
> 1. Fuel pressure test - ok
> 2. Coolant temp sensor - ok
> 3. PCV - ok
> 4. Air filter - new
> 5. EGR - 100% working ok
> 6. B-map - ok
> 7. TPS - ok
> 8. Injector Balance - ok
> 9. Plugs, Wires - New
> 10. Throttle body - cleaned, ok
> 11. AIS Motor - ok
> 12. Air control motor - ok
>
> He couldn't figure out what the problem was, but suggested I simply
> put it through the test with a gallon of alcohol.
>
> I filled up the gas tank with Mobil Super +, and drove around for a
> week to clean the fuel lines through. I filled up again with Mobil
> Super +, added a quart of dry gas and a gallon of denatured alcohol
> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
> it 15 miles and put it through inspection.
>
> To my amazement, I got the following results:
>
> Gas Standard Reading Result
> HC 100 30 Pass
> CO% 0.50 0.61 Fail
> CO2% 14.1
> RPM 2430
>
> I'm like .... WTF????
>
> I've been told the local gas stations are putting additives in the gas
> in this area due to the weather, and a lot of cars are losing fuel
> consumption and failing emissions inspections. But this is
> ridiculous. I can hardly import a tank of gas from Florida, so what
> the hell else can I do to get this thing to pass?
>
> Any suggestions gratefully received, short of "move to a state with
> less draconian measures".
> --
> Blue Moon

 

It is really going to come back down to an oxygen sensor problem of some
sort. I have to assume alot to arrive at this, such as the fact that your
mechanic was thorough in checking the O2 sensor operation. The computer is
commanding a fuel mixture based on what it sees as inputs, and if there are
no DTC's, it is probably safe to assume that the computer is happy with what
it sees as the final product: an O2 sensor that toggles from rich to lean
nicely while staying within fuel trim parameters. It is possible, and not
unusual, to get faulty O2 sensors off the shelf. I highly recommend buying
one from the dealer and installing it, so that you know you have a quality
part plugged in.

The catalytic converter is good, as evidenced by the healthy CO2 number.
Winter fuel has it's problems, including a marked decrease in fuel economy,
but it doesn't usually wreck emissions. If it did, all of your neighbors
would be having the same problem.

Start with the air intake, make sure it isn't restricted anywhere (I have
seen mice build nests in the air intake, and also well-intentioned shop
towels that make their way into the air intake tube.). Replace the PCV
valve if you can't remember the last time you did so. If you are equipped
with a multimeter, check the ground side voltage drop from the engine to
battery negative, should be less than .2V. If higher, you have a faulty
ground, and a faulty ground will produce a faulty O2 sensor reading.

Don't spend any more money on ignition components, this is strictly a fuel
mixture problem. Give us updates, so we know what works and what doesn't.

Jerry

"Blue Moon" <mfoco@hotmail.com> wrote in message
news:68b9a6502cd0b4ab8563e8007f3678b8@news.teranew s.com...
> Hi all,
>
> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
> with passing emissions inspection in north NJ (Sussex County). The
> original results were:
>
> Gas Standard Reading Result
> HC 100 27 Pass
> CO% 0.50 0.69 Fail
> CO2% 13.9
> RPM 2668
>
> No figures were given for NOx or O2%.
>
> Okay, no big problem, thinks I. The following parts were replaced:
>
> Oil filter & oil
> Air filter
> 8 Spark plugs
> Plug wires (including the distributor/coil wire)
> Oxygen Sensor
>
> A mechanic checked the vehicle out, and had a friend of his test
> emissions. Despite the vehicle running excellently (no pings, knocks,
> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
> down to about 0.51 - 0.52.
>
> He tested a load of parts, and reported the following:
>
> 1. Fuel pressure test - ok
> 2. Coolant temp sensor - ok
> 3. PCV - ok
> 4. Air filter - new
> 5. EGR - 100% working ok
> 6. B-map - ok
> 7. TPS - ok
> 8. Injector Balance - ok
> 9. Plugs, Wires - New
> 10. Throttle body - cleaned, ok
> 11. AIS Motor - ok
> 12. Air control motor - ok
>
> He couldn't figure out what the problem was, but suggested I simply
> put it through the test with a gallon of alcohol.
>
> I filled up the gas tank with Mobil Super +, and drove around for a
> week to clean the fuel lines through. I filled up again with Mobil
> Super +, added a quart of dry gas and a gallon of denatured alcohol
> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
> it 15 miles and put it through inspection.
>
> To my amazement, I got the following results:
>
> Gas Standard Reading Result
> HC 100 30 Pass
> CO% 0.50 0.61 Fail
> CO2% 14.1
> RPM 2430
>
> I'm like .... WTF????
>
> I've been told the local gas stations are putting additives in the gas
> in this area due to the weather, and a lot of cars are losing fuel
> consumption and failing emissions inspections. But this is
> ridiculous. I can hardly import a tank of gas from Florida, so what
> the hell else can I do to get this thing to pass?
>
> Any suggestions gratefully received, short of "move to a state with
> less draconian measures".
> --
> Blue Moon

 

It is really going to come back down to an oxygen sensor problem of some
sort. I have to assume alot to arrive at this, such as the fact that your
mechanic was thorough in checking the O2 sensor operation. The computer is
commanding a fuel mixture based on what it sees as inputs, and if there are
no DTC's, it is probably safe to assume that the computer is happy with what
it sees as the final product: an O2 sensor that toggles from rich to lean
nicely while staying within fuel trim parameters. It is possible, and not
unusual, to get faulty O2 sensors off the shelf. I highly recommend buying
one from the dealer and installing it, so that you know you have a quality
part plugged in.

The catalytic converter is good, as evidenced by the healthy CO2 number.
Winter fuel has it's problems, including a marked decrease in fuel economy,
but it doesn't usually wreck emissions. If it did, all of your neighbors
would be having the same problem.

Start with the air intake, make sure it isn't restricted anywhere (I have
seen mice build nests in the air intake, and also well-intentioned shop
towels that make their way into the air intake tube.). Replace the PCV
valve if you can't remember the last time you did so. If you are equipped
with a multimeter, check the ground side voltage drop from the engine to
battery negative, should be less than .2V. If higher, you have a faulty
ground, and a faulty ground will produce a faulty O2 sensor reading.

Don't spend any more money on ignition components, this is strictly a fuel
mixture problem. Give us updates, so we know what works and what doesn't.

Jerry

"Blue Moon" <mfoco@hotmail.com> wrote in message
news:68b9a6502cd0b4ab8563e8007f3678b8@news.teranew s.com...
> Hi all,
>
> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
> with passing emissions inspection in north NJ (Sussex County). The
> original results were:
>
> Gas Standard Reading Result
> HC 100 27 Pass
> CO% 0.50 0.69 Fail
> CO2% 13.9
> RPM 2668
>
> No figures were given for NOx or O2%.
>
> Okay, no big problem, thinks I. The following parts were replaced:
>
> Oil filter & oil
> Air filter
> 8 Spark plugs
> Plug wires (including the distributor/coil wire)
> Oxygen Sensor
>
> A mechanic checked the vehicle out, and had a friend of his test
> emissions. Despite the vehicle running excellently (no pings, knocks,
> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
> down to about 0.51 - 0.52.
>
> He tested a load of parts, and reported the following:
>
> 1. Fuel pressure test - ok
> 2. Coolant temp sensor - ok
> 3. PCV - ok
> 4. Air filter - new
> 5. EGR - 100% working ok
> 6. B-map - ok
> 7. TPS - ok
> 8. Injector Balance - ok
> 9. Plugs, Wires - New
> 10. Throttle body - cleaned, ok
> 11. AIS Motor - ok
> 12. Air control motor - ok
>
> He couldn't figure out what the problem was, but suggested I simply
> put it through the test with a gallon of alcohol.
>
> I filled up the gas tank with Mobil Super +, and drove around for a
> week to clean the fuel lines through. I filled up again with Mobil
> Super +, added a quart of dry gas and a gallon of denatured alcohol
> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
> it 15 miles and put it through inspection.
>
> To my amazement, I got the following results:
>
> Gas Standard Reading Result
> HC 100 30 Pass
> CO% 0.50 0.61 Fail
> CO2% 14.1
> RPM 2430
>
> I'm like .... WTF????
>
> I've been told the local gas stations are putting additives in the gas
> in this area due to the weather, and a lot of cars are losing fuel
> consumption and failing emissions inspections. But this is
> ridiculous. I can hardly import a tank of gas from Florida, so what
> the hell else can I do to get this thing to pass?
>
> Any suggestions gratefully received, short of "move to a state with
> less draconian measures".
> --
> Blue Moon

 

Hi, thanks for the response.

I bought the O2 sensor from Napa. I'll have to see if I can test it.
If I simply return it, there's no guarantee I'll get a good
replacement. It's also not exactly convenient to go get the car
reinspected for each alteration. For that reason alone I may have to
just throw a load of $ at the local Jeep/Chrysler service centre.

What I do find puzzling is how the CO has slipped so much since the
mechanic got it tested.

I'll look into a new PCV valve, though the mechanic said it was ok.

I do have a multimeter. Are you referring to a difference in voltage
between battery+/battery- and battery+/engine block?

On Sat, 24 Jan 2004 15:18:09 -0500, "Jerry Newton"
<figatmcttelecom.com> wrote:

>It is really going to come back down to an oxygen sensor problem of some
>sort. I have to assume alot to arrive at this, such as the fact that your
>mechanic was thorough in checking the O2 sensor operation. The computer is
>commanding a fuel mixture based on what it sees as inputs, and if there are
>no DTC's, it is probably safe to assume that the computer is happy with what
>it sees as the final product: an O2 sensor that toggles from rich to lean
>nicely while staying within fuel trim parameters. It is possible, and not
>unusual, to get faulty O2 sensors off the shelf. I highly recommend buying
>one from the dealer and installing it, so that you know you have a quality
>part plugged in.
>
>The catalytic converter is good, as evidenced by the healthy CO2 number.
>Winter fuel has it's problems, including a marked decrease in fuel economy,
>but it doesn't usually wreck emissions. If it did, all of your neighbors
>would be having the same problem.
>
>Start with the air intake, make sure it isn't restricted anywhere (I have
>seen mice build nests in the air intake, and also well-intentioned shop
>towels that make their way into the air intake tube.). Replace the PCV
>valve if you can't remember the last time you did so. If you are equipped
>with a multimeter, check the ground side voltage drop from the engine to
>battery negative, should be less than .2V. If higher, you have a faulty
>ground, and a faulty ground will produce a faulty O2 sensor reading.
>
>Don't spend any more money on ignition components, this is strictly a fuel
>mixture problem. Give us updates, so we know what works and what doesn't.
>
>Jerry
>
>"Blue Moon" <mfoco@hotmail.com> wrote in message
>news:68b9a6502cd0b4ab8563e8007f3678b8@news.terane ws.com...
>> Hi all,
>>
>> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
>> with passing emissions inspection in north NJ (Sussex County). The
>> original results were:
>>
>> Gas Standard Reading Result
>> HC 100 27 Pass
>> CO% 0.50 0.69 Fail
>> CO2% 13.9
>> RPM 2668
>>
>> No figures were given for NOx or O2%.
>>
>> Okay, no big problem, thinks I. The following parts were replaced:
>>
>> Oil filter & oil
>> Air filter
>> 8 Spark plugs
>> Plug wires (including the distributor/coil wire)
>> Oxygen Sensor
>>
>> A mechanic checked the vehicle out, and had a friend of his test
>> emissions. Despite the vehicle running excellently (no pings, knocks,
>> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
>> down to about 0.51 - 0.52.
>>
>> He tested a load of parts, and reported the following:
>>
>> 1. Fuel pressure test - ok
>> 2. Coolant temp sensor - ok
>> 3. PCV - ok
>> 4. Air filter - new
>> 5. EGR - 100% working ok
>> 6. B-map - ok
>> 7. TPS - ok
>> 8. Injector Balance - ok
>> 9. Plugs, Wires - New
>> 10. Throttle body - cleaned, ok
>> 11. AIS Motor - ok
>> 12. Air control motor - ok
>>
>> He couldn't figure out what the problem was, but suggested I simply
>> put it through the test with a gallon of alcohol.
>>
>> I filled up the gas tank with Mobil Super +, and drove around for a
>> week to clean the fuel lines through. I filled up again with Mobil
>> Super +, added a quart of dry gas and a gallon of denatured alcohol
>> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
>> it 15 miles and put it through inspection.
>>
>> To my amazement, I got the following results:
>>
>> Gas Standard Reading Result
>> HC 100 30 Pass
>> CO% 0.50 0.61 Fail
>> CO2% 14.1
>> RPM 2430
>>
>> I'm like .... WTF????
>>
>> I've been told the local gas stations are putting additives in the gas
>> in this area due to the weather, and a lot of cars are losing fuel
>> consumption and failing emissions inspections. But this is
>> ridiculous. I can hardly import a tank of gas from Florida, so what
>> the hell else can I do to get this thing to pass?
>>
>> Any suggestions gratefully received, short of "move to a state with
>> less draconian measures".
>> --
>> Blue Moon
>

--
Blue Moon

 

Hi, thanks for the response.

I bought the O2 sensor from Napa. I'll have to see if I can test it.
If I simply return it, there's no guarantee I'll get a good
replacement. It's also not exactly convenient to go get the car
reinspected for each alteration. For that reason alone I may have to
just throw a load of $ at the local Jeep/Chrysler service centre.

What I do find puzzling is how the CO has slipped so much since the
mechanic got it tested.

I'll look into a new PCV valve, though the mechanic said it was ok.

I do have a multimeter. Are you referring to a difference in voltage
between battery+/battery- and battery+/engine block?

On Sat, 24 Jan 2004 15:18:09 -0500, "Jerry Newton"
<figatmcttelecom.com> wrote:

>It is really going to come back down to an oxygen sensor problem of some
>sort. I have to assume alot to arrive at this, such as the fact that your
>mechanic was thorough in checking the O2 sensor operation. The computer is
>commanding a fuel mixture based on what it sees as inputs, and if there are
>no DTC's, it is probably safe to assume that the computer is happy with what
>it sees as the final product: an O2 sensor that toggles from rich to lean
>nicely while staying within fuel trim parameters. It is possible, and not
>unusual, to get faulty O2 sensors off the shelf. I highly recommend buying
>one from the dealer and installing it, so that you know you have a quality
>part plugged in.
>
>The catalytic converter is good, as evidenced by the healthy CO2 number.
>Winter fuel has it's problems, including a marked decrease in fuel economy,
>but it doesn't usually wreck emissions. If it did, all of your neighbors
>would be having the same problem.
>
>Start with the air intake, make sure it isn't restricted anywhere (I have
>seen mice build nests in the air intake, and also well-intentioned shop
>towels that make their way into the air intake tube.). Replace the PCV
>valve if you can't remember the last time you did so. If you are equipped
>with a multimeter, check the ground side voltage drop from the engine to
>battery negative, should be less than .2V. If higher, you have a faulty
>ground, and a faulty ground will produce a faulty O2 sensor reading.
>
>Don't spend any more money on ignition components, this is strictly a fuel
>mixture problem. Give us updates, so we know what works and what doesn't.
>
>Jerry
>
>"Blue Moon" <mfoco@hotmail.com> wrote in message
>news:68b9a6502cd0b4ab8563e8007f3678b8@news.terane ws.com...
>> Hi all,
>>
>> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
>> with passing emissions inspection in north NJ (Sussex County). The
>> original results were:
>>
>> Gas Standard Reading Result
>> HC 100 27 Pass
>> CO% 0.50 0.69 Fail
>> CO2% 13.9
>> RPM 2668
>>
>> No figures were given for NOx or O2%.
>>
>> Okay, no big problem, thinks I. The following parts were replaced:
>>
>> Oil filter & oil
>> Air filter
>> 8 Spark plugs
>> Plug wires (including the distributor/coil wire)
>> Oxygen Sensor
>>
>> A mechanic checked the vehicle out, and had a friend of his test
>> emissions. Despite the vehicle running excellently (no pings, knocks,
>> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
>> down to about 0.51 - 0.52.
>>
>> He tested a load of parts, and reported the following:
>>
>> 1. Fuel pressure test - ok
>> 2. Coolant temp sensor - ok
>> 3. PCV - ok
>> 4. Air filter - new
>> 5. EGR - 100% working ok
>> 6. B-map - ok
>> 7. TPS - ok
>> 8. Injector Balance - ok
>> 9. Plugs, Wires - New
>> 10. Throttle body - cleaned, ok
>> 11. AIS Motor - ok
>> 12. Air control motor - ok
>>
>> He couldn't figure out what the problem was, but suggested I simply
>> put it through the test with a gallon of alcohol.
>>
>> I filled up the gas tank with Mobil Super +, and drove around for a
>> week to clean the fuel lines through. I filled up again with Mobil
>> Super +, added a quart of dry gas and a gallon of denatured alcohol
>> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
>> it 15 miles and put it through inspection.
>>
>> To my amazement, I got the following results:
>>
>> Gas Standard Reading Result
>> HC 100 30 Pass
>> CO% 0.50 0.61 Fail
>> CO2% 14.1
>> RPM 2430
>>
>> I'm like .... WTF????
>>
>> I've been told the local gas stations are putting additives in the gas
>> in this area due to the weather, and a lot of cars are losing fuel
>> consumption and failing emissions inspections. But this is
>> ridiculous. I can hardly import a tank of gas from Florida, so what
>> the hell else can I do to get this thing to pass?
>>
>> Any suggestions gratefully received, short of "move to a state with
>> less draconian measures".
>> --
>> Blue Moon
>

--
Blue Moon

 

Hi, thanks for the response.

I bought the O2 sensor from Napa. I'll have to see if I can test it.
If I simply return it, there's no guarantee I'll get a good
replacement. It's also not exactly convenient to go get the car
reinspected for each alteration. For that reason alone I may have to
just throw a load of $ at the local Jeep/Chrysler service centre.

What I do find puzzling is how the CO has slipped so much since the
mechanic got it tested.

I'll look into a new PCV valve, though the mechanic said it was ok.

I do have a multimeter. Are you referring to a difference in voltage
between battery+/battery- and battery+/engine block?

On Sat, 24 Jan 2004 15:18:09 -0500, "Jerry Newton"
<figatmcttelecom.com> wrote:

>It is really going to come back down to an oxygen sensor problem of some
>sort. I have to assume alot to arrive at this, such as the fact that your
>mechanic was thorough in checking the O2 sensor operation. The computer is
>commanding a fuel mixture based on what it sees as inputs, and if there are
>no DTC's, it is probably safe to assume that the computer is happy with what
>it sees as the final product: an O2 sensor that toggles from rich to lean
>nicely while staying within fuel trim parameters. It is possible, and not
>unusual, to get faulty O2 sensors off the shelf. I highly recommend buying
>one from the dealer and installing it, so that you know you have a quality
>part plugged in.
>
>The catalytic converter is good, as evidenced by the healthy CO2 number.
>Winter fuel has it's problems, including a marked decrease in fuel economy,
>but it doesn't usually wreck emissions. If it did, all of your neighbors
>would be having the same problem.
>
>Start with the air intake, make sure it isn't restricted anywhere (I have
>seen mice build nests in the air intake, and also well-intentioned shop
>towels that make their way into the air intake tube.). Replace the PCV
>valve if you can't remember the last time you did so. If you are equipped
>with a multimeter, check the ground side voltage drop from the engine to
>battery negative, should be less than .2V. If higher, you have a faulty
>ground, and a faulty ground will produce a faulty O2 sensor reading.
>
>Don't spend any more money on ignition components, this is strictly a fuel
>mixture problem. Give us updates, so we know what works and what doesn't.
>
>Jerry
>
>"Blue Moon" <mfoco@hotmail.com> wrote in message
>news:68b9a6502cd0b4ab8563e8007f3678b8@news.terane ws.com...
>> Hi all,
>>
>> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
>> with passing emissions inspection in north NJ (Sussex County). The
>> original results were:
>>
>> Gas Standard Reading Result
>> HC 100 27 Pass
>> CO% 0.50 0.69 Fail
>> CO2% 13.9
>> RPM 2668
>>
>> No figures were given for NOx or O2%.
>>
>> Okay, no big problem, thinks I. The following parts were replaced:
>>
>> Oil filter & oil
>> Air filter
>> 8 Spark plugs
>> Plug wires (including the distributor/coil wire)
>> Oxygen Sensor
>>
>> A mechanic checked the vehicle out, and had a friend of his test
>> emissions. Despite the vehicle running excellently (no pings, knocks,
>> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
>> down to about 0.51 - 0.52.
>>
>> He tested a load of parts, and reported the following:
>>
>> 1. Fuel pressure test - ok
>> 2. Coolant temp sensor - ok
>> 3. PCV - ok
>> 4. Air filter - new
>> 5. EGR - 100% working ok
>> 6. B-map - ok
>> 7. TPS - ok
>> 8. Injector Balance - ok
>> 9. Plugs, Wires - New
>> 10. Throttle body - cleaned, ok
>> 11. AIS Motor - ok
>> 12. Air control motor - ok
>>
>> He couldn't figure out what the problem was, but suggested I simply
>> put it through the test with a gallon of alcohol.
>>
>> I filled up the gas tank with Mobil Super +, and drove around for a
>> week to clean the fuel lines through. I filled up again with Mobil
>> Super +, added a quart of dry gas and a gallon of denatured alcohol
>> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
>> it 15 miles and put it through inspection.
>>
>> To my amazement, I got the following results:
>>
>> Gas Standard Reading Result
>> HC 100 30 Pass
>> CO% 0.50 0.61 Fail
>> CO2% 14.1
>> RPM 2430
>>
>> I'm like .... WTF????
>>
>> I've been told the local gas stations are putting additives in the gas
>> in this area due to the weather, and a lot of cars are losing fuel
>> consumption and failing emissions inspections. But this is
>> ridiculous. I can hardly import a tank of gas from Florida, so what
>> the hell else can I do to get this thing to pass?
>>
>> Any suggestions gratefully received, short of "move to a state with
>> less draconian measures".
>> --
>> Blue Moon
>

--
Blue Moon

 

There isn't any accurate way to field test an oxygen sensor. It will switch
voltage like it is supposed to, I suppose, but you can't tell if the
calibration is shifted, and that is what will tend to happen.

I didn't see that the CO number moved appreciably from the first test to the
second test. .01% isn't anything to get excited about, you are looking for
..5% drop. A few hundredths, or even a couple of tenths of a percent is
normal variation, and is present if you just swing the car around and
immediately test it again. You are looking for the magic bullet that will
swing it down near zero, and near zero is absolutely attainable with a good
catalytic converter, which you seem to have.

No, NAPA won't give you your money back on the sensor. You live and learn
about things like oxygen sensors. I don't know how much NAPA charged for
it, dealer is probably gonna nail you for $75-$100.

A voltage drop test measures the potential from one point in a circuit to
another to determine the integrity of the circuit. What you want to do is
set your DVOM to DC volts, put one lead on the intake manifold or other
convenient engine part, and the other lead to the negative battery post.
This will produce a small amount of voltage, because there is voltage drop
across any circuit. The idea is to keep it under .2V or 200mV. (Same
thing) This test needs to be performed with the circuit loaded i.e. engine
running at normal operating temp. This same criteria applies to any circuit
that you test this way, and is darned reliable.

An ohmeter will show a circuit to have less than 5 ohms resistance, even if
there is only one strand of wire holding it together. A voltage drop test
will tell you whether current can actually flow through a circuit. In the
case of electronic fuel injection, the computer is relying on a good ground
to provide accurate feedback information. It only knows what it sees, it
doesn't know if the ground has deteriorated, and it cannot compensate for
things like that. In cases like this, there is a saying: think like the
box. If you were a computer, think about why you would be fattening up the
mixture based on what the various inputs told you. That will lead you to
probable causes of failure.

I understand that you can't run back to the testing station every time to
make a change. You alluded to the most logical choice: take it to the
dealer and let them tell you what's wrong. Look at how much you have spent
already. For under a hundred bucks, they will tell you what it is, and you
can stop throwing money at it. It may be something that you don't want to
tackle anyway, then you can make a happy mechanic by giving him something to
fix.

Let us know how you proceed, I am interested.


Jerry


"Blue Moon" <mfoco@hotmail.com> wrote in message
news:165aef83e28bb9c2b67a396d73beb017@news.teranew s.com...
> Hi, thanks for the response.
>
> I bought the O2 sensor from Napa. I'll have to see if I can test it.
> If I simply return it, there's no guarantee I'll get a good
> replacement. It's also not exactly convenient to go get the car
> reinspected for each alteration. For that reason alone I may have to
> just throw a load of $ at the local Jeep/Chrysler service centre.
>
> What I do find puzzling is how the CO has slipped so much since the
> mechanic got it tested.
>
> I'll look into a new PCV valve, though the mechanic said it was ok.
>
> I do have a multimeter. Are you referring to a difference in voltage
> between battery+/battery- and battery+/engine block?
>
> On Sat, 24 Jan 2004 15:18:09 -0500, "Jerry Newton"
> <figatmcttelecom.com> wrote:
>
> >It is really going to come back down to an oxygen sensor problem of some
> >sort. I have to assume alot to arrive at this, such as the fact that
your
> >mechanic was thorough in checking the O2 sensor operation. The computer
is
> >commanding a fuel mixture based on what it sees as inputs, and if there
are
> >no DTC's, it is probably safe to assume that the computer is happy with
what
> >it sees as the final product: an O2 sensor that toggles from rich to lean
> >nicely while staying within fuel trim parameters. It is possible, and
not
> >unusual, to get faulty O2 sensors off the shelf. I highly recommend
buying
> >one from the dealer and installing it, so that you know you have a
quality
> >part plugged in.
> >
> >The catalytic converter is good, as evidenced by the healthy CO2 number.
> >Winter fuel has it's problems, including a marked decrease in fuel
economy,
> >but it doesn't usually wreck emissions. If it did, all of your neighbors
> >would be having the same problem.
> >
> >Start with the air intake, make sure it isn't restricted anywhere (I have
> >seen mice build nests in the air intake, and also well-intentioned shop
> >towels that make their way into the air intake tube.). Replace the PCV
> >valve if you can't remember the last time you did so. If you are
equipped
> >with a multimeter, check the ground side voltage drop from the engine to
> >battery negative, should be less than .2V. If higher, you have a faulty
> >ground, and a faulty ground will produce a faulty O2 sensor reading.
> >
> >Don't spend any more money on ignition components, this is strictly a
fuel
> >mixture problem. Give us updates, so we know what works and what
doesn't.
> >
> >Jerry
> >
> >"Blue Moon" <mfoco@hotmail.com> wrote in message
> >news:68b9a6502cd0b4ab8563e8007f3678b8@news.terane ws.com...
> >> Hi all,
> >>
> >> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
> >> with passing emissions inspection in north NJ (Sussex County). The
> >> original results were:
> >>
> >> Gas Standard Reading Result
> >> HC 100 27 Pass
> >> CO% 0.50 0.69 Fail
> >> CO2% 13.9
> >> RPM 2668
> >>
> >> No figures were given for NOx or O2%.
> >>
> >> Okay, no big problem, thinks I. The following parts were replaced:
> >>
> >> Oil filter & oil
> >> Air filter
> >> 8 Spark plugs
> >> Plug wires (including the distributor/coil wire)
> >> Oxygen Sensor
> >>
> >> A mechanic checked the vehicle out, and had a friend of his test
> >> emissions. Despite the vehicle running excellently (no pings, knocks,
> >> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
> >> down to about 0.51 - 0.52.
> >>
> >> He tested a load of parts, and reported the following:
> >>
> >> 1. Fuel pressure test - ok
> >> 2. Coolant temp sensor - ok
> >> 3. PCV - ok
> >> 4. Air filter - new
> >> 5. EGR - 100% working ok
> >> 6. B-map - ok
> >> 7. TPS - ok
> >> 8. Injector Balance - ok
> >> 9. Plugs, Wires - New
> >> 10. Throttle body - cleaned, ok
> >> 11. AIS Motor - ok
> >> 12. Air control motor - ok
> >>
> >> He couldn't figure out what the problem was, but suggested I simply
> >> put it through the test with a gallon of alcohol.
> >>
> >> I filled up the gas tank with Mobil Super +, and drove around for a
> >> week to clean the fuel lines through. I filled up again with Mobil
> >> Super +, added a quart of dry gas and a gallon of denatured alcohol
> >> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
> >> it 15 miles and put it through inspection.
> >>
> >> To my amazement, I got the following results:
> >>
> >> Gas Standard Reading Result
> >> HC 100 30 Pass
> >> CO% 0.50 0.61 Fail
> >> CO2% 14.1
> >> RPM 2430
> >>
> >> I'm like .... WTF????
> >>
> >> I've been told the local gas stations are putting additives in the gas
> >> in this area due to the weather, and a lot of cars are losing fuel
> >> consumption and failing emissions inspections. But this is
> >> ridiculous. I can hardly import a tank of gas from Florida, so what
> >> the hell else can I do to get this thing to pass?
> >>
> >> Any suggestions gratefully received, short of "move to a state with
> >> less draconian measures".
> >> --
> >> Blue Moon
> >
>
> --
> Blue Moon

 

There isn't any accurate way to field test an oxygen sensor. It will switch
voltage like it is supposed to, I suppose, but you can't tell if the
calibration is shifted, and that is what will tend to happen.

I didn't see that the CO number moved appreciably from the first test to the
second test. .01% isn't anything to get excited about, you are looking for
..5% drop. A few hundredths, or even a couple of tenths of a percent is
normal variation, and is present if you just swing the car around and
immediately test it again. You are looking for the magic bullet that will
swing it down near zero, and near zero is absolutely attainable with a good
catalytic converter, which you seem to have.

No, NAPA won't give you your money back on the sensor. You live and learn
about things like oxygen sensors. I don't know how much NAPA charged for
it, dealer is probably gonna nail you for $75-$100.

A voltage drop test measures the potential from one point in a circuit to
another to determine the integrity of the circuit. What you want to do is
set your DVOM to DC volts, put one lead on the intake manifold or other
convenient engine part, and the other lead to the negative battery post.
This will produce a small amount of voltage, because there is voltage drop
across any circuit. The idea is to keep it under .2V or 200mV. (Same
thing) This test needs to be performed with the circuit loaded i.e. engine
running at normal operating temp. This same criteria applies to any circuit
that you test this way, and is darned reliable.

An ohmeter will show a circuit to have less than 5 ohms resistance, even if
there is only one strand of wire holding it together. A voltage drop test
will tell you whether current can actually flow through a circuit. In the
case of electronic fuel injection, the computer is relying on a good ground
to provide accurate feedback information. It only knows what it sees, it
doesn't know if the ground has deteriorated, and it cannot compensate for
things like that. In cases like this, there is a saying: think like the
box. If you were a computer, think about why you would be fattening up the
mixture based on what the various inputs told you. That will lead you to
probable causes of failure.

I understand that you can't run back to the testing station every time to
make a change. You alluded to the most logical choice: take it to the
dealer and let them tell you what's wrong. Look at how much you have spent
already. For under a hundred bucks, they will tell you what it is, and you
can stop throwing money at it. It may be something that you don't want to
tackle anyway, then you can make a happy mechanic by giving him something to
fix.

Let us know how you proceed, I am interested.


Jerry


"Blue Moon" <mfoco@hotmail.com> wrote in message
news:165aef83e28bb9c2b67a396d73beb017@news.teranew s.com...
> Hi, thanks for the response.
>
> I bought the O2 sensor from Napa. I'll have to see if I can test it.
> If I simply return it, there's no guarantee I'll get a good
> replacement. It's also not exactly convenient to go get the car
> reinspected for each alteration. For that reason alone I may have to
> just throw a load of $ at the local Jeep/Chrysler service centre.
>
> What I do find puzzling is how the CO has slipped so much since the
> mechanic got it tested.
>
> I'll look into a new PCV valve, though the mechanic said it was ok.
>
> I do have a multimeter. Are you referring to a difference in voltage
> between battery+/battery- and battery+/engine block?
>
> On Sat, 24 Jan 2004 15:18:09 -0500, "Jerry Newton"
> <figatmcttelecom.com> wrote:
>
> >It is really going to come back down to an oxygen sensor problem of some
> >sort. I have to assume alot to arrive at this, such as the fact that
your
> >mechanic was thorough in checking the O2 sensor operation. The computer
is
> >commanding a fuel mixture based on what it sees as inputs, and if there
are
> >no DTC's, it is probably safe to assume that the computer is happy with
what
> >it sees as the final product: an O2 sensor that toggles from rich to lean
> >nicely while staying within fuel trim parameters. It is possible, and
not
> >unusual, to get faulty O2 sensors off the shelf. I highly recommend
buying
> >one from the dealer and installing it, so that you know you have a
quality
> >part plugged in.
> >
> >The catalytic converter is good, as evidenced by the healthy CO2 number.
> >Winter fuel has it's problems, including a marked decrease in fuel
economy,
> >but it doesn't usually wreck emissions. If it did, all of your neighbors
> >would be having the same problem.
> >
> >Start with the air intake, make sure it isn't restricted anywhere (I have
> >seen mice build nests in the air intake, and also well-intentioned shop
> >towels that make their way into the air intake tube.). Replace the PCV
> >valve if you can't remember the last time you did so. If you are
equipped
> >with a multimeter, check the ground side voltage drop from the engine to
> >battery negative, should be less than .2V. If higher, you have a faulty
> >ground, and a faulty ground will produce a faulty O2 sensor reading.
> >
> >Don't spend any more money on ignition components, this is strictly a
fuel
> >mixture problem. Give us updates, so we know what works and what
doesn't.
> >
> >Jerry
> >
> >"Blue Moon" <mfoco@hotmail.com> wrote in message
> >news:68b9a6502cd0b4ab8563e8007f3678b8@news.terane ws.com...
> >> Hi all,
> >>
> >> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
> >> with passing emissions inspection in north NJ (Sussex County). The
> >> original results were:
> >>
> >> Gas Standard Reading Result
> >> HC 100 27 Pass
> >> CO% 0.50 0.69 Fail
> >> CO2% 13.9
> >> RPM 2668
> >>
> >> No figures were given for NOx or O2%.
> >>
> >> Okay, no big problem, thinks I. The following parts were replaced:
> >>
> >> Oil filter & oil
> >> Air filter
> >> 8 Spark plugs
> >> Plug wires (including the distributor/coil wire)
> >> Oxygen Sensor
> >>
> >> A mechanic checked the vehicle out, and had a friend of his test
> >> emissions. Despite the vehicle running excellently (no pings, knocks,
> >> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
> >> down to about 0.51 - 0.52.
> >>
> >> He tested a load of parts, and reported the following:
> >>
> >> 1. Fuel pressure test - ok
> >> 2. Coolant temp sensor - ok
> >> 3. PCV - ok
> >> 4. Air filter - new
> >> 5. EGR - 100% working ok
> >> 6. B-map - ok
> >> 7. TPS - ok
> >> 8. Injector Balance - ok
> >> 9. Plugs, Wires - New
> >> 10. Throttle body - cleaned, ok
> >> 11. AIS Motor - ok
> >> 12. Air control motor - ok
> >>
> >> He couldn't figure out what the problem was, but suggested I simply
> >> put it through the test with a gallon of alcohol.
> >>
> >> I filled up the gas tank with Mobil Super +, and drove around for a
> >> week to clean the fuel lines through. I filled up again with Mobil
> >> Super +, added a quart of dry gas and a gallon of denatured alcohol
> >> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
> >> it 15 miles and put it through inspection.
> >>
> >> To my amazement, I got the following results:
> >>
> >> Gas Standard Reading Result
> >> HC 100 30 Pass
> >> CO% 0.50 0.61 Fail
> >> CO2% 14.1
> >> RPM 2430
> >>
> >> I'm like .... WTF????
> >>
> >> I've been told the local gas stations are putting additives in the gas
> >> in this area due to the weather, and a lot of cars are losing fuel
> >> consumption and failing emissions inspections. But this is
> >> ridiculous. I can hardly import a tank of gas from Florida, so what
> >> the hell else can I do to get this thing to pass?
> >>
> >> Any suggestions gratefully received, short of "move to a state with
> >> less draconian measures".
> >> --
> >> Blue Moon
> >
>
> --
> Blue Moon

 

There isn't any accurate way to field test an oxygen sensor. It will switch
voltage like it is supposed to, I suppose, but you can't tell if the
calibration is shifted, and that is what will tend to happen.

I didn't see that the CO number moved appreciably from the first test to the
second test. .01% isn't anything to get excited about, you are looking for
..5% drop. A few hundredths, or even a couple of tenths of a percent is
normal variation, and is present if you just swing the car around and
immediately test it again. You are looking for the magic bullet that will
swing it down near zero, and near zero is absolutely attainable with a good
catalytic converter, which you seem to have.

No, NAPA won't give you your money back on the sensor. You live and learn
about things like oxygen sensors. I don't know how much NAPA charged for
it, dealer is probably gonna nail you for $75-$100.

A voltage drop test measures the potential from one point in a circuit to
another to determine the integrity of the circuit. What you want to do is
set your DVOM to DC volts, put one lead on the intake manifold or other
convenient engine part, and the other lead to the negative battery post.
This will produce a small amount of voltage, because there is voltage drop
across any circuit. The idea is to keep it under .2V or 200mV. (Same
thing) This test needs to be performed with the circuit loaded i.e. engine
running at normal operating temp. This same criteria applies to any circuit
that you test this way, and is darned reliable.

An ohmeter will show a circuit to have less than 5 ohms resistance, even if
there is only one strand of wire holding it together. A voltage drop test
will tell you whether current can actually flow through a circuit. In the
case of electronic fuel injection, the computer is relying on a good ground
to provide accurate feedback information. It only knows what it sees, it
doesn't know if the ground has deteriorated, and it cannot compensate for
things like that. In cases like this, there is a saying: think like the
box. If you were a computer, think about why you would be fattening up the
mixture based on what the various inputs told you. That will lead you to
probable causes of failure.

I understand that you can't run back to the testing station every time to
make a change. You alluded to the most logical choice: take it to the
dealer and let them tell you what's wrong. Look at how much you have spent
already. For under a hundred bucks, they will tell you what it is, and you
can stop throwing money at it. It may be something that you don't want to
tackle anyway, then you can make a happy mechanic by giving him something to
fix.

Let us know how you proceed, I am interested.


Jerry


"Blue Moon" <mfoco@hotmail.com> wrote in message
news:165aef83e28bb9c2b67a396d73beb017@news.teranew s.com...
> Hi, thanks for the response.
>
> I bought the O2 sensor from Napa. I'll have to see if I can test it.
> If I simply return it, there's no guarantee I'll get a good
> replacement. It's also not exactly convenient to go get the car
> reinspected for each alteration. For that reason alone I may have to
> just throw a load of $ at the local Jeep/Chrysler service centre.
>
> What I do find puzzling is how the CO has slipped so much since the
> mechanic got it tested.
>
> I'll look into a new PCV valve, though the mechanic said it was ok.
>
> I do have a multimeter. Are you referring to a difference in voltage
> between battery+/battery- and battery+/engine block?
>
> On Sat, 24 Jan 2004 15:18:09 -0500, "Jerry Newton"
> <figatmcttelecom.com> wrote:
>
> >It is really going to come back down to an oxygen sensor problem of some
> >sort. I have to assume alot to arrive at this, such as the fact that
your
> >mechanic was thorough in checking the O2 sensor operation. The computer
is
> >commanding a fuel mixture based on what it sees as inputs, and if there
are
> >no DTC's, it is probably safe to assume that the computer is happy with
what
> >it sees as the final product: an O2 sensor that toggles from rich to lean
> >nicely while staying within fuel trim parameters. It is possible, and
not
> >unusual, to get faulty O2 sensors off the shelf. I highly recommend
buying
> >one from the dealer and installing it, so that you know you have a
quality
> >part plugged in.
> >
> >The catalytic converter is good, as evidenced by the healthy CO2 number.
> >Winter fuel has it's problems, including a marked decrease in fuel
economy,
> >but it doesn't usually wreck emissions. If it did, all of your neighbors
> >would be having the same problem.
> >
> >Start with the air intake, make sure it isn't restricted anywhere (I have
> >seen mice build nests in the air intake, and also well-intentioned shop
> >towels that make their way into the air intake tube.). Replace the PCV
> >valve if you can't remember the last time you did so. If you are
equipped
> >with a multimeter, check the ground side voltage drop from the engine to
> >battery negative, should be less than .2V. If higher, you have a faulty
> >ground, and a faulty ground will produce a faulty O2 sensor reading.
> >
> >Don't spend any more money on ignition components, this is strictly a
fuel
> >mixture problem. Give us updates, so we know what works and what
doesn't.
> >
> >Jerry
> >
> >"Blue Moon" <mfoco@hotmail.com> wrote in message
> >news:68b9a6502cd0b4ab8563e8007f3678b8@news.terane ws.com...
> >> Hi all,
> >>
> >> I have a 1994 Jeep Grand Cherokee, 8 cylinder. I am having problems
> >> with passing emissions inspection in north NJ (Sussex County). The
> >> original results were:
> >>
> >> Gas Standard Reading Result
> >> HC 100 27 Pass
> >> CO% 0.50 0.69 Fail
> >> CO2% 13.9
> >> RPM 2668
> >>
> >> No figures were given for NOx or O2%.
> >>
> >> Okay, no big problem, thinks I. The following parts were replaced:
> >>
> >> Oil filter & oil
> >> Air filter
> >> 8 Spark plugs
> >> Plug wires (including the distributor/coil wire)
> >> Oxygen Sensor
> >>
> >> A mechanic checked the vehicle out, and had a friend of his test
> >> emissions. Despite the vehicle running excellently (no pings, knocks,
> >> stalls, bad starts, dirty exhaust etc.) they could only get the CO%
> >> down to about 0.51 - 0.52.
> >>
> >> He tested a load of parts, and reported the following:
> >>
> >> 1. Fuel pressure test - ok
> >> 2. Coolant temp sensor - ok
> >> 3. PCV - ok
> >> 4. Air filter - new
> >> 5. EGR - 100% working ok
> >> 6. B-map - ok
> >> 7. TPS - ok
> >> 8. Injector Balance - ok
> >> 9. Plugs, Wires - New
> >> 10. Throttle body - cleaned, ok
> >> 11. AIS Motor - ok
> >> 12. Air control motor - ok
> >>
> >> He couldn't figure out what the problem was, but suggested I simply
> >> put it through the test with a gallon of alcohol.
> >>
> >> I filled up the gas tank with Mobil Super +, and drove around for a
> >> week to clean the fuel lines through. I filled up again with Mobil
> >> Super +, added a quart of dry gas and a gallon of denatured alcohol
> >> (so I'm guessing the tank would have had about 4% - 5% alcohol), drove
> >> it 15 miles and put it through inspection.
> >>
> >> To my amazement, I got the following results:
> >>
> >> Gas Standard Reading Result
> >> HC 100 30 Pass
> >> CO% 0.50 0.61 Fail
> >> CO2% 14.1
> >> RPM 2430
> >>
> >> I'm like .... WTF????
> >>
> >> I've been told the local gas stations are putting additives in the gas
> >> in this area due to the weather, and a lot of cars are losing fuel
> >> consumption and failing emissions inspections. But this is
> >> ridiculous. I can hardly import a tank of gas from Florida, so what
> >> the hell else can I do to get this thing to pass?
> >>
> >> Any suggestions gratefully received, short of "move to a state with
> >> less draconian measures".
> >> --
> >> Blue Moon
> >
>
> --
> Blue Moon