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Jeep Cherokee Grand Cherokee Engine and Performance Problems



  • Well first things want to start with the most basic, most importantly, cheapest things first. (I just realized how old this post If the fuel pump goes out it won't crank at can turn the key to the ON position just before trying to start it. You should hear the fuel pump kick on for just a sec or two at the rear of the vehicle (it is at the top of the gas tank). In the fuel system I would start with the fuel filter first. People would be amazed to know the types of problems which can be caused by not keeping up with regular maintenance of a vehicle (changing the oil and oil filter, changing the fuel filter, changing the spark plugs and spark plug wires, chainging the air filter.) I had a 1994 Jeep Grand Cherokee with the inline 6 cylinder engine. Very simple cars to work on. Its system does not have things such as a throttle adjustment screw...if it is not idling or running correctly start with these minor things first (according to the symptoms of the issue you are having...starting system, etc...). You have to drop the gas tank to get to the fuel pump on these vehicles...its not that difficult but a new one does cost about $300. Had to do this on mine while I owned it. These tips can be used with almost all vehicles...they are all very similar. Except for CHRYSLER!!!! Steer clear of those!!!! lol. My wife owns a 97 Sebring and it has given me and all mechanics I know more problems than any vehicle.
  • my 1996 gc laredo w 218.000 miles has been dying while driving or coming to a stop. The oil pressure dropped to zero just before. No "check engine light". I could restart it immediately dropping into neutral while coasting along. this worked good on freeways but it's stressful to say the least. Have had my mechanic replace coolant sensor, temp sensor, crank position sensor & new battery & belt. Display kept showing "bad coolant sensor. Then it wouldn't start. Finally took it to jeep dealer who replaced plugs & wires, cleaned distributor, new gasket on valve cover for $700. Said they wouldn't reset the computer module. After driving it for 4 hours and about 300 miles running just great it up and dies again, once when stopping, then when underway. Jeep dealer says it needs a new PCM & ignition coil for another $1000. Hate give up this car as it goes anywhere and is a joy to drive, but is it worth it now? Anyone with any more ideas?
  • b_webb_web Posts: 4
    I just went through this with my 94 JGC. I did all the same things you did. It did end up being the PCM. Once the PCM was replaced for $500 I have had no issues. When you think about it, it makes sense. It is a very old computer, how long is it supposed to last. Mine was in bad shape when they pulled it off. It also corrected my hard starting problem. Good luck.
  • Hi...did you ever get a fix for your misfire issue? I have been returning mine for updates and checks for this for 10 months. Finally pulled spark plugs myself and found two cylinders appearing to burning very lean and a couple others looking rich and some indications of oil going through them. Finally got call from Customer service and was told no codes so no problem!!!!! Informed her that issue showed up after about 3,000 and was minor annoyance but has continually gotten worse. they did not codes, no problem was the set "line". Email me if possible and let me know?
  • halo2halo2 Posts: 11
    No--Finally had the factory tech come in an drive it--he said that the hesitation is a normal function of the multi displacement system that switches between 8 cylinders and 4. He said to over ride it put it in 5th gear or push the tow haul button. That works some, but I should not have to do that. I love everything about the jeep gc except the hemi with MDS. I'll guarantee you that the next one I buy will not have the Hemi in it.
  • I have a 2000 Jeep Grand Cherokee 4.7 litre V8 engine and have had it in the shop and have been shopping around for a rebuilt engine at the request of the mechanic I use. When the problem occurred the temp gauge maxed out twice then it started making a clanking noise so I pulled over and had it towed to my garage.The mechanic said it would be less expensive purchasing a rebuilt motor for it rather than spending the time finding what the problem is and then fix it.Any resemblances or suggestions would greatly help ( my pocket book also)
  • Unreal...the last time mine was in (about 2 weeks ago) they told me this was a combination of the MDS, the torque converter locking and unlocking and how lean they were running the engine. NO ANSWERS as to why it was not present when new nor any explanation as to why it has gotten worse.

    NO WAY a "premium" vehicle that we paid money for should run like this. I could have purchased a 10K little puddle jumper that would not run like this. I am extremely disappointed with this running issue on this makes it worse that I love the looks, drive and features but will likely not buy Jeep again.
  • My 95 Jeep has a weird issue. the only way to start it is to turn the key to on position and wait until the fuel pump and auto shut off relays start clicking and then stop. Once the relays stop clicking it will start. I can shut it off and immediately restart but if i leave it off for more than a few minutes i have to wait until the relays start clicking and stop again before it will start. I notice if i leave the battery terminals off and let the computer reset this process doesn't take as long...any ideas?
  • b_webb_web Posts: 4
    I had the exact same problem with my 94 JGC. After replacing every sensor under the hood and my fuel pump, the result was the computer. After I replaced the computer it ran like new and it fires right up even in cold weather. Good luck.
  • Just fixed mine after trying foreever to fix it. It was the idle control motor. Has not been a problem since. They cleaned it and works great. 100 dollar fix
  • There is a backflow valve associated with the electric fuel pump. Failure of this valve allows all the fuel in the fuel line to drain back into the fuel tank. This requires the pump to run longer than normal to refill the line and supply fuel for starting.
  • My jeep just started to lose the oil pressure and check gauges light comes on...this only happens when the motor is warm and in idle...example when I drive to and from work as I am halfway to work/home and stop at a light or traffic the oil gauge will start to drop and the check gauges light will flash. Has the right amount of oil....but the light goes away when I step on gas!?!?!
    Was told this could be the oil pump???? Need help since I need to get this fixed but dont want to get screwed by dealership/repair shop and overpay if its something simple and easy fix. Help Please!!!
  • cskicski West Springfield, VAPosts: 1,501
    Which engine do you have? Have you tried putting it in neutral as you come to a light to see if the problem remains? Also, u mentioned that the check guages light comes on, but does the check engine light come on as well?
    Once we have a little more info then we can research the problem for you. I know how it is to face expensive repair bills. -Chris

    Chris Skalski: Network Engineer 2012 Kia Optima EX

  • V8 4.7L H.O. JGC overland. I have tried putting it in neutral as coming to a stop, and the problem still remains. Check engine light never comes on, just the check gauges light!???? Thanks for your fast response.
  • cskicski West Springfield, VAPosts: 1,501 u have a WJ series like mine. I will get back to u asap.

    Chris Skalski: Network Engineer 2012 Kia Optima EX

  • cskicski West Springfield, VAPosts: 1,501
    My mechanic and I think you may have a clogged oil pump with solids that could accumulate if the engine oil was not changed for a long time. (previous own may not have maintained it).

    The pan needs to come off so it can be inspected. If you are lucky, it could be a bad ending unit/sensor.

    Have it checked immediately.If you fry the engine it will be a very expensive repair. Good luck! :=)

    Chris Skalski: Network Engineer 2012 Kia Optima EX

  • thanks for the info. I've had this jeep for the past 6 yrs and have had the same mechanic change the oil every 3000 miles. it can run 200-300 miles with no problems and good oil pressure, then suddenly when driving the engine shuts off. Oil pressure may drop. other times when coming to a stop, say at a signal, the rpm dropps and the oil pressure drops and engine turns off. it starts right back up and then keeps running. mechanic changed oil pressure sensor, crank (something), and coolant temp sensor. dealer mechanic says now it's the PMC which needs replacement for $1000.
  • kjo12kjo12 Posts: 2
    edited December 2011
    I am having the same problem with my 2011 GC Hemi engine. Called Chrysler and they said I needed to start at the dealership level. I am quite sure I will find out the same thing everyone else has found. Does anyone have any new information? There is no current recall and it was suggested I contact National Highway Traffic and Safety at 888-327-4236 or This is the agency that creates recalls.
  • halo2halo2 Posts: 11
    Regional Technician drove mine and said it is the MDS system normal operation. It still has a very noticeable hesitation 30-70 MPH--Drives me crazy--I hate that engine. To by-pass MDS he said to run it in 5th gear or switch tow/haul on. It works most of the time but there is still a hesitation, but not as bad. It will slightly effect your gas mileage. I doubt that NHTSA will do anything as it is not a safety issue. If anyone here's of any fixes, please let me know.
  • cskicski West Springfield, VAPosts: 1,501
    Well, I think your mechanic may want to consider that is may be the ECU. (Engine Control Unit). You can get a completly programed and ready to install unit for 199.00 at ebay motors. When I bought mine it didnt want to shift into overdrive, stalled for no reason, guages would stop working, etc. Nightmare. New ECU fixed all of it. Dealer will charge you $1200 so dont do it there! -Chris

    Chris Skalski: Network Engineer 2012 Kia Optima EX

  • After further mechanic and I found multiple things...first off I had about 3 cracked tubes around the top of the motor that connected to the pcv valve, also my air filter was replaced at a company that I will leave out but they put in the wrong air filter which didn't allow for a good seal! Replaced my sensor for the oil check gauges, did an oil change with a mopar oil filter, changed my spark plugs and found that the plugs were off gap spec!! All in all my oil pump was fine so after returning oil pump and including all above...I fixed my issue with $150 budget...that including the beer for my mechanic!!
  • cskicski West Springfield, VAPosts: 1,501
    Sounds like the oil pressure sensor did the trick. I am glad u got all the other stuff done too. To get plugs at the dealer....just the plugs...$125. So u got a sweet deal. Buy him a case next time and maybe he will drop a Hemi in it for $500! :shades:

    Chris Skalski: Network Engineer 2012 Kia Optima EX

  • I am having some issues with my 1993 jeep cherokee 6 cylinder...first off when I am driving on flat surfaces it seems alright with lots of power,but when I go to climb hills it heats up and loses power slowing me down from 55 miles per hour to 20 mph up hill what is going on with my jeep??At this point the overheating occurs. But I did notice oil on my manifold..
  • This isn't a solution but are you driving in overdrive when climbing? I've had several cars which overheat going up hills in overdrive. I've since started going into drive or on some cars, 3rd. Seems to provide more power without straining and overheating the engine. Hope this helps get you to the top.
  • gcat1gcat1 Posts: 2
    I also have a 2011 that was manufactured in Feb 2011 and it has the same problem -- did you get any help from your dealer or Chrysler on this?
  • halo2halo2 Posts: 11
    Nope---The company line is it is the normal operation of the MDS system---It has gotten worse.
  • I have a 97 jeep grand cherokee laredo 4.0 6 straight, I was driving up a hill and the jeep just quit. No warning. I pulled over and then first it wouldn't start then it started and worked ok and then it started to want to quit again and I kept giving it gas to get it home. Is this fuel pump or computer module? I have heard it could be either one. Can anyone help me? They are both really expensive so if anyone has had this trouble and got results let me know?
  • kjo12kjo12 Posts: 2
    Dealer said it was the shifting from 4 to 8 cylinders. The missing or jerking morion seems pretty violent for something as simple as this.
  • cskicski West Springfield, VAPosts: 1,501
    I would actually go test drive another Jeep with the same drive-train. See if it does the same same thing as yours.

    I think the 2011 is absolutely gorgeous. There are a great many things I love about mine still. The torque, acceleration, commanding view of the road, and the feeling of confidence that goes along with the 4x4 system.

    If it doesn't jerk or make any other unseemly noises, then ask your dear service tech to look again. I went through a lot of heartache with my 1999. Never again.


    Chris Skalski: Network Engineer 2012 Kia Optima EX

  • halo2halo2 Posts: 11
    Yep--same as mine---anyone riding with me notices it right away---If you hear of a fix, let me know. Regional Tech drove it and said it was normal operation of the MDS system----It is BS
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