I would first suspect the connection on the TPS needs a clean just
because it is a really common failure point that is heat sensitive and
controls the shift points as well as the idle speed.

A good spray electronic contact cleaner is best, but even WD40 (Water
Displacement spray) will work, just not last as long.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
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)

reboot wrote:
> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...
>
> suggestions?
>
> reboot
>
>
> ---
> avast! Antivirus: Outbound message clean.
> Virus Database (VPS): 000778-2, 10/03/2007
> Tested on: 10/4/2007 12:14:28 AM
> avast! - copyright (c) 1988-2007 ALWIL Software.
> http://www.avast.com
>
>
>

 

I would first suspect the connection on the TPS needs a clean just
because it is a really common failure point that is heat sensitive and
controls the shift points as well as the idle speed.

A good spray electronic contact cleaner is best, but even WD40 (Water
Displacement spray) will work, just not last as long.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
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)

reboot wrote:
> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...
>
> suggestions?
>
> reboot
>
>
> ---
> avast! Antivirus: Outbound message clean.
> Virus Database (VPS): 000778-2, 10/03/2007
> Tested on: 10/4/2007 12:14:28 AM
> avast! - copyright (c) 1988-2007 ALWIL Software.
> http://www.avast.com
>
>
>

 

I would first suspect the connection on the TPS needs a clean just
because it is a really common failure point that is heat sensitive and
controls the shift points as well as the idle speed.

A good spray electronic contact cleaner is best, but even WD40 (Water
Displacement spray) will work, just not last as long.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
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)

reboot wrote:
> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...
>
> suggestions?
>
> reboot
>
>
> ---
> avast! Antivirus: Outbound message clean.
> Virus Database (VPS): 000778-2, 10/03/2007
> Tested on: 10/4/2007 12:14:28 AM
> avast! - copyright (c) 1988-2007 ALWIL Software.
> http://www.avast.com
>
>
>

 

reboot wrote:

> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...

When I first got my 88 MJ, I fought a similar problem for several months
before I finally got most of it cured. Biggest improvement was a really
thorough cleaning of the throttle body - don't forget to use a drill or
pipe cleaner to get the port for the map sensor cleaned. Next was a
complete tuneup - but that helped starting and high end more than anything.
Cleaned all the electrical connectors on the throttle body, O2 sensor, map
senor, and CPS. All helped some but light throttle just off idle was still
problematic. A new O2 sensor fixed that (old one seemed to test good, but
idle mixture was obviously rich). This thing had been rode hard and put
away wet before I got it so everything was cruddy.

After all that, I still have one problem that I haven't figured out. Cold
start, air temp in the 35 - 40F range, the damned thing is going to stall
and die at the stop sign at the bottom of the hill. Just once, just at the
first stop, just at that "in-between" temperature.

OK, I have the older Renix computer so that could be a difference but the
point of this is that it was apparently a combination of little thing with
each one contributing to the problem.

You seem to be saying that it happens during warmup and goes away when full
temp is reached. Have you checked the temp sensor? The computer uses a
separate sensor rather than the one that drives the gauge, so I would at
least look to make sure that the computer wasn't getting a false temp and
coming out of the open loop mode too soon.

--
Will Honea

--
Posted via a free Usenet account from http://www.teranews.com

 

reboot wrote:

> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...

When I first got my 88 MJ, I fought a similar problem for several months
before I finally got most of it cured. Biggest improvement was a really
thorough cleaning of the throttle body - don't forget to use a drill or
pipe cleaner to get the port for the map sensor cleaned. Next was a
complete tuneup - but that helped starting and high end more than anything.
Cleaned all the electrical connectors on the throttle body, O2 sensor, map
senor, and CPS. All helped some but light throttle just off idle was still
problematic. A new O2 sensor fixed that (old one seemed to test good, but
idle mixture was obviously rich). This thing had been rode hard and put
away wet before I got it so everything was cruddy.

After all that, I still have one problem that I haven't figured out. Cold
start, air temp in the 35 - 40F range, the damned thing is going to stall
and die at the stop sign at the bottom of the hill. Just once, just at the
first stop, just at that "in-between" temperature.

OK, I have the older Renix computer so that could be a difference but the
point of this is that it was apparently a combination of little thing with
each one contributing to the problem.

You seem to be saying that it happens during warmup and goes away when full
temp is reached. Have you checked the temp sensor? The computer uses a
separate sensor rather than the one that drives the gauge, so I would at
least look to make sure that the computer wasn't getting a false temp and
coming out of the open loop mode too soon.

--
Will Honea

--
Posted via a free Usenet account from http://www.teranews.com

 

reboot wrote:

> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...

When I first got my 88 MJ, I fought a similar problem for several months
before I finally got most of it cured. Biggest improvement was a really
thorough cleaning of the throttle body - don't forget to use a drill or
pipe cleaner to get the port for the map sensor cleaned. Next was a
complete tuneup - but that helped starting and high end more than anything.
Cleaned all the electrical connectors on the throttle body, O2 sensor, map
senor, and CPS. All helped some but light throttle just off idle was still
problematic. A new O2 sensor fixed that (old one seemed to test good, but
idle mixture was obviously rich). This thing had been rode hard and put
away wet before I got it so everything was cruddy.

After all that, I still have one problem that I haven't figured out. Cold
start, air temp in the 35 - 40F range, the damned thing is going to stall
and die at the stop sign at the bottom of the hill. Just once, just at the
first stop, just at that "in-between" temperature.

OK, I have the older Renix computer so that could be a difference but the
point of this is that it was apparently a combination of little thing with
each one contributing to the problem.

You seem to be saying that it happens during warmup and goes away when full
temp is reached. Have you checked the temp sensor? The computer uses a
separate sensor rather than the one that drives the gauge, so I would at
least look to make sure that the computer wasn't getting a false temp and
coming out of the open loop mode too soon.

--
Will Honea

--
Posted via a free Usenet account from http://www.teranews.com

 

reboot wrote:

> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...

When I first got my 88 MJ, I fought a similar problem for several months
before I finally got most of it cured. Biggest improvement was a really
thorough cleaning of the throttle body - don't forget to use a drill or
pipe cleaner to get the port for the map sensor cleaned. Next was a
complete tuneup - but that helped starting and high end more than anything.
Cleaned all the electrical connectors on the throttle body, O2 sensor, map
senor, and CPS. All helped some but light throttle just off idle was still
problematic. A new O2 sensor fixed that (old one seemed to test good, but
idle mixture was obviously rich). This thing had been rode hard and put
away wet before I got it so everything was cruddy.

After all that, I still have one problem that I haven't figured out. Cold
start, air temp in the 35 - 40F range, the damned thing is going to stall
and die at the stop sign at the bottom of the hill. Just once, just at the
first stop, just at that "in-between" temperature.

OK, I have the older Renix computer so that could be a difference but the
point of this is that it was apparently a combination of little thing with
each one contributing to the problem.

You seem to be saying that it happens during warmup and goes away when full
temp is reached. Have you checked the temp sensor? The computer uses a
separate sensor rather than the one that drives the gauge, so I would at
least look to make sure that the computer wasn't getting a false temp and
coming out of the open loop mode too soon.

--
Will Honea

--
Posted via a free Usenet account from http://www.teranews.com

 

take a squirt bottle and spray all the plug wires while it's running and
look for arching
and if you are brave enough while the wires are wet and engine running
place both feet so they touch each other and touch the wires if you feel
current the wires are bad but jeep your feet together or you will get
poked real good clean the throttle body to see oif that improves idle

reboot wrote:

> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...
>
> suggestions?
>
> reboot
>
> ---
> avast! Antivirus: Outbound message clean.
> Virus Database (VPS): 000778-2, 10/03/2007
> Tested on: 10/4/2007 12:14:28 AM
> avast! - copyright (c) 1988-2007 ALWIL Software.
> http://www.avast.com

 

take a squirt bottle and spray all the plug wires while it's running and
look for arching
and if you are brave enough while the wires are wet and engine running
place both feet so they touch each other and touch the wires if you feel
current the wires are bad but jeep your feet together or you will get
poked real good clean the throttle body to see oif that improves idle

reboot wrote:

> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...
>
> suggestions?
>
> reboot
>
> ---
> avast! Antivirus: Outbound message clean.
> Virus Database (VPS): 000778-2, 10/03/2007
> Tested on: 10/4/2007 12:14:28 AM
> avast! - copyright (c) 1988-2007 ALWIL Software.
> http://www.avast.com

 

take a squirt bottle and spray all the plug wires while it's running and
look for arching
and if you are brave enough while the wires are wet and engine running
place both feet so they touch each other and touch the wires if you feel
current the wires are bad but jeep your feet together or you will get
poked real good clean the throttle body to see oif that improves idle

reboot wrote:

> '99 TJ 4.0 Auto - within about 3 minutes of a cold start under part
> throttle (accelerating reasonably to 45 mph) the engine would start to
> stutter, hesitate and surge. water temperature gage shows the mid
> mark between cold and 210. when this happens and I open the throttle
> wide open it makes good power. on return to part throttle the
> hesitate and surge resumes. if i come to a stop while this is going
> on then the idle speed dips real low and sometimes stalls. runs very
> rough.
>
> if i drive it a few more minutes and get the water temperature all the
> way up it seems OK, smooth stable idle, smooth part throttle
> acceleration.
>
> in the first vista to the shop, they replaced the MAP sensor because
> it showed this code. took the truck back but the problem persisted.
>
> called the shop after this didn't fix the problem. they kept the
> truck overnight and tried it cold. didn't happen for them. they
> scanned the 'puter and no codes. they put in a set of plugs and
> replaced #6 spark plug wire because they said it looked corroded.
>
> told me drive it for a few weeks and call them back. if it fixed the
> problem we would discuss how much to pay for the 2nd visit. if it
> didn't ...
>
> so i've had the truck back a couple of weeks now and it happens pretty
> regularly. took it to Murray's this evening and hooked up a scanner -
> no codes, same as the shop with their good equipment and trained techs
> ...
>
> suggestions?
>
> reboot
>
> ---
> avast! Antivirus: Outbound message clean.
> Virus Database (VPS): 000778-2, 10/03/2007
> Tested on: 10/4/2007 12:14:28 AM
> avast! - copyright (c) 1988-2007 ALWIL Software.
> http://www.avast.com