I have a 94 Jeep Grand Cherokee 5.2 v 8 laredo 4x4 145,000 miles I'm new to the forum. I've been on the outskirts creeping on older threads trying to figure out my issues.


I bought a 94 gjc about 2months ago ran great. Two weeks ago it started to shake a little look under the jeep the muffler/exhaust pipe was shaking noticed small crack in muffler ran fine for two days, 3rd day shaking stopped, there was a softball size hole in muffler , drove it as it was for a few more days, loud but ran fine no issue, it started to missfire/and or backfire and stall out with low idle. I replaced the muffler it ran a little better still spitting and sputtering, and stalling out, it backfires while off throttle, when rpms start to lower when it misfires/and or backfire, stalling out only when stopped at lights while in gear, never while in transit, when I crank it I have to keep foot on gas to keep running. PLEASE HELP. **Note** Engine and tranny all sound good, no jerk in tranny while gear shift, no knocking, just rides rough as all hell.

THINGS DONE ALREADY.
#1. Muffler
#2 cleaned o2 sensor on exhaust pipe
#3 cleaned throttle body
#4 cleaned IAC
#5 cleaned TPS
#6 checked filters
#7 tried to check codes with key turn trick. but lost all stored codes due to removal of neg cable on batt to work on it.
Please help please
Does 94 jgc have a crank shaft position sensor? Could that cause all of this?

 

You may need to replace the IAC, cleaning it will only last for a short time. There is a crank sensor on the 5.2, it's behind the right head on the back of the block and is held in with two 13mm bolts with the heads pointing up. The 5.2 has a problem with a cover on the bottom of the intake manifold. The gasket will split and cause a vacuum leak and suck oil into the intake, could be a cause of your rough idle and stalling. How do you clean a TPS?

 

ok I will try and replace the IAC. in regards to the TPS I just took off the harness unscrew the bolts and just cleaned it with air spray, to get all grime/dirt off it, and inside the whole where it fits in with a rag. Is it hard to replace that sensor on the back of the head? I'm not very skilled in regards to engine work. Are these two things difficult , change gasket on intake manifold, change crank shaft position sensor?

 

The crank sensor is in the bellhousing behind the engine and is a PITA to get to. I have heard of guys that cut a hole in the floorpan to get to it. Not a great idea. The gasket requires removing the intake manifold.

It's best to check the crank sensor electrically before condemning it. It could just be the wiring. IDK the exact procedures, but it involves checking pin-out voltages and resistance as well as the pulse output.

 

Would the computer for the jeep cause any of this? Where is the computer on a 94 jgc ? Is it behind the resivoir for rad fluid?

 

The PCM is on the right side of the firewall, but I doubt the is the problem.

 

Busted back,, I ran engine cleaner through it yesterday, it has gotten 100% better no stalling, idle is back, but still backfires, What's the best way to test for vacuum leak? In regards to the intake manifold gasket, is this something I can I can do or do you recommend having a shop do it. I can follow instruction like every other dummy. But if requires special know how/ knowledge idk if I'm the guy.

 

after replacing a lot of things and tinkering and messing around, it was sparked plugs spark plug wires distributor cap distributor rotor loose wire in the ignition

 

Good deal! I was going to say a backfire is usually caused by a break in the ignition sequence. A loose wire can cause this. You found it.

 

yes thank you for all help, this form is beyond helpful, busted back and Dave, thank you for your help, now the new issue when I turn the AC on it stalls out the car, any info any advice would be greatly appreciated thank you all

 

The only thing I can think of that would cause that is the compressor is overloaded or back-pressured. I had a problem with a Dodge Caravan that blew 2 compressors because the evaporator orifice was freezing up and the liquid refrigerant backed up into the compressor, stalled it, and wiped out the clutch. Twice! The third time, I had an experienced tech fix it. He was the one who figured out what was happening.