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Jeep Cherokee Grand Cherokee Engine and Performance Problems

729 messages,  Last post on Mar 20, 2013 at 10:59 AM

You are in the Jeep Cherokee and Jeep Grand Cherokee Forum.

What is this discussion about? Jeep Grand Cherokee, Jeep Grand Cherokee SRT-8, Jeep Cherokee, Engine, SUV

Messages Page 8 of 74

#64 of 729 Jeep Grand Cherokee runs rough briefly by rllewis

Apr 06, 2007 (3:33 am)

My 1994 4.0 Jeep Grand Cherokee started running terrible (bucking and stalling). I replaced the crankshaft position sensor, and it ran fine...except that afterword it started bucking after about 20-30 minutes after starting. It runs rough like this for about a minute...then runs fine again. It has done this without fail, every day for the last 6 months.
It never stalls, and always starts.
When it starts bucking, it slows down to around 40 mph, not fun when you are on interstate. Giving it more gas results in more bucking. It is definitely temperature related, during cold weather it takes longer to manifest.
I have checked the coolant & manifold temperature sensors, MAP sensor, camshaft position sensor, and fuel pressure. I have replaced the spark plugs, rotor, wires, and fuel filter.
I only get this problem for 1 minute, then it's gone.
 
The onset of the problem is gradual (15 seconds), and it clears up over a 15 second period as well.

#65 of 729 Re: Jeep Grand Cherokee runs rough briefly [rllewis] by bethjohnson

Apr 20, 2007 (9:59 am)

Replying to: rllewis (Apr 06, 2007 3:33 am)
I have the same exact problem with my 1994 4.0 Jeep Grand Cherokee. Have you found a solution?

#66 of 729 Re: Jeep Grand Cherokee runs rough briefly [bethjohnson] by rllewis

May 01, 2007 (7:08 pm)

Replying to: bethjohnson (Apr 20, 2007 9:59 am)
Yes. I was able to monitor the crankshaft position sensor output long enough to see the signal go bonkers when the 1 minute problem happened. I replaced the sensor (which was under warranty) and now it is fixed. So the whole time it was the part I originally replaced. What are the odds?
 
The part costs about $70.

#67 of 729 Re: Jeep Grand Cherokee runs rough briefly [rllewis] by antheil

May 02, 2007 (10:07 am)

Replying to: rllewis (May 01, 2007 7:08 pm)
How did you monitor the crank sensor output?

#68 of 729 92 Jeep Cherokee Engine Control Module by charlene2

Dec 19, 2005 (6:29 am)

My daughter has a 92 Jeep Cherokee in which she was told the engine contol module was bad. I bought a manual for the jeep, but there is no information about the module. Can anyone tell me where the module is, what it looks like, where to get one and how to replace it?

#69 of 729 Re: 92 Jeep Cherokee Engine Control Module [charlene2] by mullins87

Dec 19, 2005 (8:22 pm)

Replying to: charlene2 (Dec 19, 2005 6:29 am)
The ECM is located under the hood. I don't have an older Cherokee, but on my '01 it is located in the driver side front corner near the air cleaner. The ECM on my '95 Wrangler is located, still under the hood, on the drivers side rear corner near the brake booster.
 
The ECM will be a black box approximately 6" tall by 8" long and will have a large wiring harness connected to it. The harness should be fairly easy to trace. I don't know how you can check yours without having another Jeep you could try it on.
 
You should be able to go to ebay and find some. Be sure to check with a professional first, but I'm thinking you can use any year ECM from '92 to '95, just so long as the engine and transmission are correct.

#70 of 729 Re: 92 Jeep Cherokee Engine Control Module [mullins87] by mullins87

Dec 19, 2005 (8:27 pm)

Replying to: mullins87 (Dec 19, 2005 8:22 pm)
I just did a quick search for you on ebay by typing in "jeep computer". BTW: I am in no way connected to this auction.
 
link title
 
I'm not telling you to buy this one. I only provided this link as an example of what you might look for.

#71 of 729 Re: 92 Jeep Cherokee Engine Control Module [charlene2] by mullins87

Dec 24, 2005 (10:44 am)

Replying to: charlene2 (Dec 19, 2005 6:29 am)
Well? How'd it turn out?

#72 of 729 94 cherokee rough idle by gardman

Jan 30, 2006 (3:52 pm)

i just replaced my 94 cherokee's 4.0 engine with a new rebuilt engine by hesco. new plugs, wires, rotor, dist cap, gaskets etc. the engine runs great at speed but exhibits a very rough idle. i've replaced the cam sensor, the o2 sensor, and cleaned the throttle body and idle air control. no improvement at all. any ideas

#73 of 729 Re: 94 cherokee rough idle [gardman] by mullins87

Feb 03, 2006 (4:16 pm)

Replying to: gardman (Jan 30, 2006 3:52 pm)
Have you ruled out a vacuum leak? The timing could be set too high.

Messages Page 8 of 74

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