Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

So something is up with the cold start circuit. Hmm....

Ok, maybe two problems? Your first issue was with crap in the gas.
Maybe you caused the second issue? Just a wild assed guess, but there
are a bad run of distributor caps and rotors out on the market for the
4.0 engine. The rotors are too short which causes arcing and a cold
engine miss for a while, then a miss all the time.

Someone voiced the opinion the parts were made in two different
factories or countries and they don't mate up together properly.

Cold start misses can also be a bad or leaky plug wire. Even one just
not pushed on tight. New ones can be bad too. I check them by spray
misting them with water when it's dark out.

Mike

jeepr wrote:
>
> Mike
> it has all been done since the problem occurred.
> Like I said the fuel tank has been cleaned. the fuel pump and filter
> replaced, injector flush, decarb the valves and all those components
> replaced and nothing has fixed the problem, nothing showing on the read outs
> from all test boxes, and it only when cold' so can't be hoodlum's
>
> --
>
> Matt
> 0|||||||0
> Tact is the ability to describe others as they see themselves
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:44249A4A.DA8617F8@sympatico.ca...
> > Was the maintenance done because of the miss? If not how much was
> > before and after?
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> > Canadian Off Road Trips Photos: Non members can still view!
> > Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> > (More Off Road album links at bottom of the view page)
> >
> > jeepr wrote:
> > >
> > > 98 zj, 6 cyl. Runs rough after starting, when engine warm runs smooth.
> > > No check engine light. Have done maintenance in following order
> > > 1. New plugs, new wires,new rotor,new cap
> > > 1a. Took off fuel rail; full of crap, install fuel rail and do injection
> > > flush.
> > > Worked great for about 3 weeks symptoms reappear.
> > > 2. Drop fuel tank have steam cleaned, replace intank fuel pump, do a
> > > injection flush from fuel tank forward.
> > > Now have about $1200 invested in repairs and symptoms are still there.
> > >
> > > Have hooked up the dealer pilot computer to record conditions when
> symptoms
> > > occur with nil negative pick ups
> > > Dealer has done there chemical carbon cleaning of intake valves, twice
> > > dealer baroscopic the valves and there is no carbon on valves
> > >
> > > Have replaced the following with no positive results;
> > > Crankshaft Position sensor
> > > O2 sensors
> > > Engine Coolant Sensor
> > > The Main Computer
> > >
> > > No check engine light and runs rough when cold when first accelerating
> as
> > > the accelerator is push vehicle will smooth out and
> > > accelerate, like its missing on some cylinders.
> > > Does not latch any code.
> > >
> > > Matt
> > > 0|||||||0
> > > Tact is the ability to describe others as they see themselves

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

So something is up with the cold start circuit. Hmm....

Ok, maybe two problems? Your first issue was with crap in the gas.
Maybe you caused the second issue? Just a wild assed guess, but there
are a bad run of distributor caps and rotors out on the market for the
4.0 engine. The rotors are too short which causes arcing and a cold
engine miss for a while, then a miss all the time.

Someone voiced the opinion the parts were made in two different
factories or countries and they don't mate up together properly.

Cold start misses can also be a bad or leaky plug wire. Even one just
not pushed on tight. New ones can be bad too. I check them by spray
misting them with water when it's dark out.

Mike

jeepr wrote:
>
> Mike
> it has all been done since the problem occurred.
> Like I said the fuel tank has been cleaned. the fuel pump and filter
> replaced, injector flush, decarb the valves and all those components
> replaced and nothing has fixed the problem, nothing showing on the read outs
> from all test boxes, and it only when cold' so can't be hoodlum's
>
> --
>
> Matt
> 0|||||||0
> Tact is the ability to describe others as they see themselves
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:44249A4A.DA8617F8@sympatico.ca...
> > Was the maintenance done because of the miss? If not how much was
> > before and after?
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> > Canadian Off Road Trips Photos: Non members can still view!
> > Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> > (More Off Road album links at bottom of the view page)
> >
> > jeepr wrote:
> > >
> > > 98 zj, 6 cyl. Runs rough after starting, when engine warm runs smooth.
> > > No check engine light. Have done maintenance in following order
> > > 1. New plugs, new wires,new rotor,new cap
> > > 1a. Took off fuel rail; full of crap, install fuel rail and do injection
> > > flush.
> > > Worked great for about 3 weeks symptoms reappear.
> > > 2. Drop fuel tank have steam cleaned, replace intank fuel pump, do a
> > > injection flush from fuel tank forward.
> > > Now have about $1200 invested in repairs and symptoms are still there.
> > >
> > > Have hooked up the dealer pilot computer to record conditions when
> symptoms
> > > occur with nil negative pick ups
> > > Dealer has done there chemical carbon cleaning of intake valves, twice
> > > dealer baroscopic the valves and there is no carbon on valves
> > >
> > > Have replaced the following with no positive results;
> > > Crankshaft Position sensor
> > > O2 sensors
> > > Engine Coolant Sensor
> > > The Main Computer
> > >
> > > No check engine light and runs rough when cold when first accelerating
> as
> > > the accelerator is push vehicle will smooth out and
> > > accelerate, like its missing on some cylinders.
> > > Does not latch any code.
> > >
> > > Matt
> > > 0|||||||0
> > > Tact is the ability to describe others as they see themselves

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

If it is a fuel injector problem, you and your mechanic may end up
having to pull every one of them for further cleaning and testing.
Cold starts require a lot of fuel to pass through them, and if one is
partially clogged, the engine will run pretty rough.

-JD

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

If it is a fuel injector problem, you and your mechanic may end up
having to pull every one of them for further cleaning and testing.
Cold starts require a lot of fuel to pass through them, and if one is
partially clogged, the engine will run pretty rough.

-JD

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

If it is a fuel injector problem, you and your mechanic may end up
having to pull every one of them for further cleaning and testing.
Cold starts require a lot of fuel to pass through them, and if one is
partially clogged, the engine will run pretty rough.

-JD

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

JD Adams did pass the time by typing:
> If it is a fuel injector problem, you and your mechanic may end up
> having to pull every one of them for further cleaning and testing.
> Cold starts require a lot of fuel to pass through them, and if one is
> partially clogged, the engine will run pretty rough.

For injectors, the easiest approach is to yank them and take them
to a local shop that specializes in injector cleaning and testing.
(usually listed under diesel engine repair)

I've had mine cleaned and tested. It cost far less than replacing
one and verified that electrical and flow characteristics were within
spec. You can actually see them test the spray pattern and volume.

Almost made me think about building my own tester cleaner. Didn't look
that terribly complicated. Mostly just plastic plumbing, a pump, and
control circuit to fire the injector for a given time or cycle it while
cleaning.

Here is a link that shows some of the equipment they use.
http://www.lindertech.com/reconinj.htm

--
DougW

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

JD Adams did pass the time by typing:
> If it is a fuel injector problem, you and your mechanic may end up
> having to pull every one of them for further cleaning and testing.
> Cold starts require a lot of fuel to pass through them, and if one is
> partially clogged, the engine will run pretty rough.

For injectors, the easiest approach is to yank them and take them
to a local shop that specializes in injector cleaning and testing.
(usually listed under diesel engine repair)

I've had mine cleaned and tested. It cost far less than replacing
one and verified that electrical and flow characteristics were within
spec. You can actually see them test the spray pattern and volume.

Almost made me think about building my own tester cleaner. Didn't look
that terribly complicated. Mostly just plastic plumbing, a pump, and
control circuit to fire the injector for a given time or cycle it while
cleaning.

Here is a link that shows some of the equipment they use.
http://www.lindertech.com/reconinj.htm

--
DougW

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

JD Adams did pass the time by typing:
> If it is a fuel injector problem, you and your mechanic may end up
> having to pull every one of them for further cleaning and testing.
> Cold starts require a lot of fuel to pass through them, and if one is
> partially clogged, the engine will run pretty rough.

For injectors, the easiest approach is to yank them and take them
to a local shop that specializes in injector cleaning and testing.
(usually listed under diesel engine repair)

I've had mine cleaned and tested. It cost far less than replacing
one and verified that electrical and flow characteristics were within
spec. You can actually see them test the spray pattern and volume.

Almost made me think about building my own tester cleaner. Didn't look
that terribly complicated. Mostly just plastic plumbing, a pump, and
control circuit to fire the injector for a given time or cycle it while
cleaning.

Here is a link that shows some of the equipment they use.
http://www.lindertech.com/reconinj.htm

--
DougW

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

Mike
the motor has 124k km on it.
When I took off the cap and rotor to replace them as the first step, the
rotor was pretty much eroded and the cap contacts and been pretty much wore
down so I got a crappy tire set along with the wires and threw them in.
The gas issue I'm guessing came from using shell gas about 4-5 years back
when they had the defective additive in it. I remember reading about a
class action suit for people getting their tanks cleaned.
I've been asking around and these are some suggestion from other people,
could you comment on their possibilities;
1. cam lobe flat spot
2. timing off, check marks on gears
3. leaky injector

Thanks for your reply. I pretty much have alot or respect for your
opinions.

--

Matt
0|||||||0
Tact is the ability to describe others as they see themselves
"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4425599C.5B7456F@sympatico.ca...
> So something is up with the cold start circuit. Hmm....
>
> Ok, maybe two problems? Your first issue was with crap in the gas.
> Maybe you caused the second issue? Just a wild assed guess, but there
> are a bad run of distributor caps and rotors out on the market for the
> 4.0 engine. The rotors are too short which causes arcing and a cold
> engine miss for a while, then a miss all the time.
>
> Someone voiced the opinion the parts were made in two different
> factories or countries and they don't mate up together properly.
>
> Cold start misses can also be a bad or leaky plug wire. Even one just
> not pushed on tight. New ones can be bad too. I check them by spray
> misting them with water when it's dark out.
>
> Mike
>
> jeepr wrote:
> >
> > Mike
> > it has all been done since the problem occurred.
> > Like I said the fuel tank has been cleaned. the fuel pump and filter
> > replaced, injector flush, decarb the valves and all those components
> > replaced and nothing has fixed the problem, nothing showing on the read
outs
> > from all test boxes, and it only when cold' so can't be hoodlum's
> >
> > --
> >
> > Matt
> > 0|||||||0
> > Tact is the ability to describe others as they see themselves
> > "Mike Romain" <romainm@sympatico.ca> wrote in message
> > news:44249A4A.DA8617F8@sympatico.ca...
> > > Was the maintenance done because of the miss? If not how much was
> > > before and after?
> > >
> > > Mike
> > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > > 88 Cherokee 235 BFG AT's
> > > Canadian Off Road Trips Photos: Non members can still view!
> > > Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> > > (More Off Road album links at bottom of the view page)
> > >
> > > jeepr wrote:
> > > >
> > > > 98 zj, 6 cyl. Runs rough after starting, when engine warm runs
smooth.
> > > > No check engine light. Have done maintenance in following order
> > > > 1. New plugs, new wires,new rotor,new cap
> > > > 1a. Took off fuel rail; full of crap, install fuel rail and do
injection
> > > > flush.
> > > > Worked great for about 3 weeks symptoms reappear.
> > > > 2. Drop fuel tank have steam cleaned, replace intank fuel pump, do a
> > > > injection flush from fuel tank forward.
> > > > Now have about $1200 invested in repairs and symptoms are still
there.
> > > >
> > > > Have hooked up the dealer pilot computer to record conditions when
> > symptoms
> > > > occur with nil negative pick ups
> > > > Dealer has done there chemical carbon cleaning of intake valves,
twice
> > > > dealer baroscopic the valves and there is no carbon on valves
> > > >
> > > > Have replaced the following with no positive results;
> > > > Crankshaft Position sensor
> > > > O2 sensors
> > > > Engine Coolant Sensor
> > > > The Main Computer
> > > >
> > > > No check engine light and runs rough when cold when first
accelerating
> > as
> > > > the accelerator is push vehicle will smooth out and
> > > > accelerate, like its missing on some cylinders.
> > > > Does not latch any code.
> > > >
> > > > Matt
> > > > 0|||||||0
> > > > Tact is the ability to describe others as they see themselves

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

Mike
the motor has 124k km on it.
When I took off the cap and rotor to replace them as the first step, the
rotor was pretty much eroded and the cap contacts and been pretty much wore
down so I got a crappy tire set along with the wires and threw them in.
The gas issue I'm guessing came from using shell gas about 4-5 years back
when they had the defective additive in it. I remember reading about a
class action suit for people getting their tanks cleaned.
I've been asking around and these are some suggestion from other people,
could you comment on their possibilities;
1. cam lobe flat spot
2. timing off, check marks on gears
3. leaky injector

Thanks for your reply. I pretty much have alot or respect for your
opinions.

--

Matt
0|||||||0
Tact is the ability to describe others as they see themselves
"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4425599C.5B7456F@sympatico.ca...
> So something is up with the cold start circuit. Hmm....
>
> Ok, maybe two problems? Your first issue was with crap in the gas.
> Maybe you caused the second issue? Just a wild assed guess, but there
> are a bad run of distributor caps and rotors out on the market for the
> 4.0 engine. The rotors are too short which causes arcing and a cold
> engine miss for a while, then a miss all the time.
>
> Someone voiced the opinion the parts were made in two different
> factories or countries and they don't mate up together properly.
>
> Cold start misses can also be a bad or leaky plug wire. Even one just
> not pushed on tight. New ones can be bad too. I check them by spray
> misting them with water when it's dark out.
>
> Mike
>
> jeepr wrote:
> >
> > Mike
> > it has all been done since the problem occurred.
> > Like I said the fuel tank has been cleaned. the fuel pump and filter
> > replaced, injector flush, decarb the valves and all those components
> > replaced and nothing has fixed the problem, nothing showing on the read
outs
> > from all test boxes, and it only when cold' so can't be hoodlum's
> >
> > --
> >
> > Matt
> > 0|||||||0
> > Tact is the ability to describe others as they see themselves
> > "Mike Romain" <romainm@sympatico.ca> wrote in message
> > news:44249A4A.DA8617F8@sympatico.ca...
> > > Was the maintenance done because of the miss? If not how much was
> > > before and after?
> > >
> > > Mike
> > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > > 88 Cherokee 235 BFG AT's
> > > Canadian Off Road Trips Photos: Non members can still view!
> > > Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> > > (More Off Road album links at bottom of the view page)
> > >
> > > jeepr wrote:
> > > >
> > > > 98 zj, 6 cyl. Runs rough after starting, when engine warm runs
smooth.
> > > > No check engine light. Have done maintenance in following order
> > > > 1. New plugs, new wires,new rotor,new cap
> > > > 1a. Took off fuel rail; full of crap, install fuel rail and do
injection
> > > > flush.
> > > > Worked great for about 3 weeks symptoms reappear.
> > > > 2. Drop fuel tank have steam cleaned, replace intank fuel pump, do a
> > > > injection flush from fuel tank forward.
> > > > Now have about $1200 invested in repairs and symptoms are still
there.
> > > >
> > > > Have hooked up the dealer pilot computer to record conditions when
> > symptoms
> > > > occur with nil negative pick ups
> > > > Dealer has done there chemical carbon cleaning of intake valves,
twice
> > > > dealer baroscopic the valves and there is no carbon on valves
> > > >
> > > > Have replaced the following with no positive results;
> > > > Crankshaft Position sensor
> > > > O2 sensors
> > > > Engine Coolant Sensor
> > > > The Main Computer
> > > >
> > > > No check engine light and runs rough when cold when first
accelerating
> > as
> > > > the accelerator is push vehicle will smooth out and
> > > > accelerate, like its missing on some cylinders.
> > > > Does not latch any code.
> > > >
> > > > Matt
> > > > 0|||||||0
> > > > Tact is the ability to describe others as they see themselves