Decided i will post a separate thread on this issue.

Vehicle detail: 1990 Cherokee, 150k, aw4.

Issue: Jeep stutters when pressing lightly on the gas while driving. It happens in every gear. Its apparent when accelerating lightly the truck feels like its pushing back and i can hear after fire in the exhaust. It seems like its around 2000 rpm. If i keep the truck in 1-2 gear and lightly accelerate i can make it misfire very violently from about 2k to 4k rpm. If i press on the gas harder the misfire is hardly noticeable it almost skips it.

What I have done so far: New TPS, adjusted and spot on. Replaced plugs, wires, rotor, cap, stator, o2 sensor. Got a coil and icm from a junk yard, still stutters the same. Compression is consistent, on a low side but all cylinders are within 10% of each other.

Other modifications: New pacesetter header (old header had a crack), new magnaflow cat, used borla catback. Obviously new intake/exhaust gasket. All the CCV system lines are brand new. I checked every ground cleaned it and sprayed with anti-corrosion spray. Replaced braided ground with nice think insulated one. Cleaned pretty much every connector and filled with dialectic(sp?) grease.

The distributor rotor does not have much play in it, probably a degree or too, so i don't think the gear is warn.

I tried to check the timing with the light but i could not see anything.

What is the proper way to check timing with a timing light on Renix jeeps? Or is there even a way to do it?

This has been a huge pain for me to figure out. I am on a verge of bringing it to a shop but i know they will either charge me 500 dollars for diagnosis or will not figure out whats going on.

What scan tool does the shop have to have to be able to diagnose Renix?

 

MAP sensor? Would have been my 4th guess you did all the other ones already.

 

Will get one later today and see.

 

I went to the local dealer and talk to the guy who has been a tech there for 35 years. He told me its the distributor. Apparently there is a 25 year old tsb that shows how to reindex the distributor. Apparently it has to be redrilled. He has a special tool that he made out of an old distribute cap that he uses to reindex the distributor. He gave me an oem original distributor cap and rotor, he todo me it will fix the issue for a short time but it will come back again soon. The issue is that the spark jumps from one cyl to another. At least thats what he told me is happening.

 

Bingo. Here is a very possible solution. Only thing is that I have no idea how to index the distributor. I need that bulletin! http://www.asashop.org/autoinc/feb99/techtotech.htm

 

So what was the problem????

200 threads and not one fix. Mine misfires under load so bad i have stopped driving it. Replaced everything but the distributor and timing chain.

I laser temp checked my fuel line (returnless 1996 XJ) and it shows 300 degrees. Is this vapor lock?

 

Remove the distributor cap and cut a "window" into the side of the distributor cap at the #1 spark plug wire post . The "window" should be large enough to allow easy visual inspection of the position of the distributor rotor at the #1 spark plug wire post. Reinstall the distributor cap.

Install a ¾" wrench or socket onto the vibration damper retaining bolt. Rotate the engine in a clockwise direction until the #1 cylinder is at top dead center. Align the timing mark on the vibration damper with the "0" degree mark on the front cover timing scale. The tip of the distributor rotor should be near the #1 spark plug wire post.

Disconnect the distributor electrical connection. Remove the distributor holddown clamp, holddown bolt and distributor. Remove the distributor cap and rotor.

Place the distributor housing upside down in a soft jaw vise. Scribe a line 1/2 inch from the end of the distributor locating tab. Cut the distributor locating tab at the scribed line with a saw.

Remove any burrs and metal filings from the distributor. Reinstall rotor.

If necessary, using a flat blade screwdriver, turn the oil pump gear drive shaft until the slot is slightly past the 11 o'clock position. The oil pump gear drive shaft is accessible through the distributor mounting bore in the engine block.

Visually align the modified locating tab area of the distributor housing with the holddown clamp bolt hole.

Turn the rotor to the 4 o'clock position.
Lower the distributor into the engine block until it seats. The rotor should now be very close to the 5 o'clock position.

Reinstall the distributor cap with the cutout "window". Rotate the distributor housing until the trailing edge of the distributor rotor tip is just departing from the #1 spark plug wire post terminal .

Reinstall the distributor holddown clamp and bolt.. Reinspect the position of the rotor to the #1 spark plug wire post to insure that it has not moved.

Install the new distributor cap, reconnect the distributor electrical connections.
Revised 07/03/2012

 

Pic of the cap.

 

Just wondering if this actually worked for you im having the same problem

 

Wondering if this is the same problem I have with misfiring.
Does anyone else Jeep run good for a while and then act up again?
Sounds like an electrical issue.
Do these distributors need any parts replaced (besides the cap and rotor)?
Mine looks all rusty inside.
I'm still working on refreshing all the wiring.
Thanks!~John

 

Mine was messing up. Pulled the cap off and the pick up under the rotor had fallen apart.
Replaced just that and it ran great again.

 

Fill out your info!!

 

Have you checked all of your fuses under the hood after replacing all those sensors? I talked a guy down $300 on my jeep cause he replaced the O2 sensors in it but it was still giving codes. I took it home, checked out the fuse box and there was the problem. Runs like a dream now. Might not be close to your problem, but worth a try. Check every one