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Jeep Cherokee Grand Cherokee Engine and Performance Problems



  • mullins87mullins87 Posts: 959
    Is it getting enough fuel and air? My guess is the fuel pump isn't pumping enough fuel, or the fuel filter is so clogged that enough fuel can't get to the engine. Is this engine injected? I thought it would have a carb.
  • mullins87mullins87 Posts: 959
    It DOES infact have a timing chain and NOT a timing belt. It is possible that your timing chain could have jumped time, but usually it will fall behind, not jump ahead. There's an ignition pickup where the distributor used to be - older engines had the distributor while your newer engine just has a small module mounted in that spot. This module IS mounted on a shaft just like the distributor and it could be slowly rotating in its mount if the hold down bolt is somehow working loose.

    Checking the timing again would be my next move. If it's off, retime the engine and put some Lock Tite on that bolt.
  • yes its MPI I used my fuel pressure tester and im getting 39 psi constant at the fuel rail no matter if I have the regulator vacuum on or off. I also replaced the fuel pressure regulator. fuel filter is also new
  • mullins87mullins87 Posts: 959
    Have you checked that pressure with the engine revved up? Sometimes a bad fuel pump will pump just enough fuel to keep the engine running at idle, but not enough to do anything else. You might try disconnecting the return line to see how much fuel is being sent back to the tank. Should be a considerable amount.
  • mullins87mullins87 Posts: 959
    With it being injected, the TPS could be the culprit. When you depress the throttle, the TPS tells the computer to send more fuel through the injectors. Well, if it's not doing its job, then when you crack open the throttle plate the engine leans out and dies.

    A repair manual should give the acceptable range of resistance for an operable TPS. Using a Ohm meter, test the sensor to see if it's bad.
  • mullins87mullins87 Posts: 959
    You started the Jeep, heard a "pop", the check engine light came on and now it's running rough??? You probably have a blown head gasket.
  • ok ill try that but would it make the motor at idle speed run really rough? shouldnt it be limited to whe you use the throttle? Mine idles really rough and sometimes will die on its own.
  • Well, typically a rough idle is caused by either a large vacuum leak or bad IAC motor. However, in your case, it is possible the throttle plate may not be closing properly.

    How does the exhaust smell at idle? Does it smell like it's running lean or rich?
  • I really wish I could be more help. But I'm the type that has to be there to see, hear and smell everything. I'm afraid my diagnostic skills are severly limited on the computer.
  • Well I figured it out.....I wnet to move the jeep for the first time since it was brought to me andwhen I put it in reverse and let the clutch out the engine roared to life for a minute then started squealing and shuttering. So I crawled underneath and noticed that two of the bell housing bolts had snapped and one was completely missing and there was brake fluid everywhere. So I pulled off the transmission/transfer case and lo and behold the clutch slave cylinder and blew apart and the main body of it had stuck itself to the input shaft of the tranny. so I replaced the bolts and slave cylinder and the thing runs like a champ..My theory is when the bolts snaped the transmission and engine seperated enough to put a bind on the motor and was bogging it dont so much that it wouldnt run right..I also had to replace the crankshaft sensor it had chewed through the sensor.. SO chalk this one up as a learning experience for me and anyone else. Do jeeps have a problem with transmission mounts going out. How do I tell if mine is or if its just extra rearend play?
  • I was wondering if anyone had a problem as mine with a 2001 Jeep GC. I drove on the highway a pretty long distance and went to grab something to eat thru a drive thru when my check gage light went off and chime. I looked at the gage for heating and it was almost close to the red overheat area. I shut off the jeep waited about a minute. Started the jeep and pulled along the side of the lot. it almost sounded like water boiling but louder. I waited about 20 minutes and then started the jeep the gage went to appx 240
    and I started to drive home (a few blocks away). I shut the jeep off at two red lights to prevent from over heating. Any idea what can be going on?
  • It could be nothing more than your thermostat, easy fix. If it overheats only when sitting still or driving slowly, then chances are it's the cooling fan. If it overheats all the time, even when driving at highway speeds, then it's the thermostat or the water pump.
  • HOLY COW!!!!! This is a new one on me. The only time I've ever heard of something like this happening is pounding the Jeep really hard offroad. So, was the input shaft all chewed up?
  • The car cooled off about two hours and I decided to go three blocks to the store. Came back and sat in the car with the heat up high the radiator fan did not kick in at all. The gage went up I think it was like 220 and the fan did not kick in. I am thinking it is the relay for the radiator fan, but not sure because that was replaced sometime earlier this year. I educated myself with this forum by reading and surely saved alot of money because a shop told me to have the fan replaced. :blush:
  • If it is the fan relay, again, then you should be able to drive it at highway speeds without overheating.
  • not at all that is what is so strange..well its over with now cant wait till the next fiasco with it:) Thanks for your insight it always helps
  • Im so glad I found this msg board cuz I'm having the exact same problem. Last week while driving to work in my 98 Jeep GC, I was at a stoplight and all of a sudden car dies. Try to start and it cranks and cranks, but won't start. Tried this for about an hour w/ no luck. Finally had to call a tow truck and tow to shop. I was relieved to find out it was only a crank something sensor that went out and wasn't that major.

    OK so here's the strange part.....2 days after getting car out of shop, today in fact I start the car and it is idling rough. Thought maybe the engine is just cold, but no, it kept on idling rough and sputtering as I accelerate. Thought it would go away but it's getting worse, to where it's almost knocking and feel like it's about to die. It's worst when I come to a complete stop, then it will idle real rough and almost shake/vibrate the car. I have to put it in neutral and then it will lessen the knocking. Then when I go, its sputtering again only louder each time. All this again after 2 days of the other repairs.

    So I bring car back to shop and he puts it under scope/pc....which say something like " ignition distributor engine module malfunction". My mechanic resets it and test drives it and says it either another sensor under the distributor that regulates air/fuel, or it's just high mileage on the vehicle (180k). So question is what should I do? I feel the shop is responsible cuz it only did this after I got my car out. And I don't think high mileage can turn my engine to the condition it is in now and so rapidly all in one day. Last time I drove car I smelled a burning smell coming from the engine. Afraid to drive it again.

    Thanks for listening and any advice would be appreciated.
  • they replaced the crankshaft sensor ..this devices tells the computer when the engine is at Top Dead Center (TDC). The mechanic cant tell you what sensor is bad?...sounds kind of iffy.
  • Your mechanic should be able to at least have an idea what's going on, that is if he/she is a competent mechanic. A code scanner can point you in the right direction. Any engine with that many miles on it is subject to exactly your problem. Sensors can go out immediately and without warning. It is possible the Crankshaft Position Sensor was not installed properly, therefore it could have shifted and is sending the computer incorrect information.

    Your problem could be any number of things. I would have the codes pulled, they should point you in some direction. I would have the CPS looked at again, just to make sure it was installed correctly. Other than that, follow where the codes lead you.
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