Hi All,

Ok I have an 88 Cherokee 4.0 5spd. About 4 years ago I replaced my motor with a rebuilt unit from a local parts store. After it was all installed I took it out for a test drive and had a bad misfire around 1800-2000 rpm. It even backfires through the exhaust. I didn't really worry about it and let the Jeep sit since I had a Wrangler at the same time so I wasn't stressed about it. Now I find myself in need of my Cherokee and have to figure this out. When I put in the motor I also installed all new sensors as well. My e.g.r. valve is not hooked up but it never has been.

Any ideas where I should look?

 

Sounds like same issue i have. Do you get it when you are light on the throttle when cruising too? Does it feel like the car is being pushed back?

on mine i am suspecting a bad distributor.

 

yeah it does feel like a push back, but if i let off or give alittle more throttle it goes away

 

yep, exactly what i have.

 

post your troubleshooting and such.

 

just for ****s and giggle hook the egr back up

 

X2 on the EGR hookup...Tj

 

mine is crimped on both sides, but the vacuum lines are still connected. Could this really be cause by egr?

 

I have the exact same issue.The guy I bought my 89 from pulled the distributor to change cap and rotor. Who knows why,but this jeep has done the same thing since.He sold it to me and said he was no mechanic and dont know what the problem is.Im gonna R AN R hte distributor and see if that fixes the problem.

 

both off you have the same thing dissconnected and the same problem what could it hurt

 

yeah, just there are many people who block off egr system and don't have any issues.

 

I've had this Jeep for 10 years and have never had the egr valve connected and had no problems with it running. As for trouble shooting, I checked for vacuum leaks (found 1 and fixed it, no help there), double checked the sensors that can be tested and even checked to make sure my distributor was installed at tdc. the only things i'm not sure about are the ignition control mod and there is no easy was to test that. If thats the problem I don't mind replacing it but on a whim $145 is a bit much.

 

Could possibly be a break down in spark due to bad plug wires or a bad coil. This is a common failure on most vehicles. If the problem gets worse when the humidity is high then it is most likey a spark jumping to ground causing this issue. Worth a check.

 

most advance auto parts can test the ignition mod.

 

Fixed the issue on mine with a new pickup coil.