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Jeep Cherokee Grand Cherokee Engine and Performance Problems



  • lvgm250lvgm250 Posts: 2
    Hi, Did you find out what the problem is? My Jeep is doing the same thing, it's also a 98. I have replaced the distributor cap, spark plugs, crank shaft position sensor, fuel injectors, fuel pump, fuel filters, fuel pressure regulator, and I cannot figure out what the problem is. It is still acting up. Please let me know if you find out. Also, my check engine light is not on and so I cannot get a diagnostic reading and the dealer says that it wouldn't be a computer problem or O2 sensor/catalytic converter issue if my check engine light isn't on. The dealer wants to charge alot to even look at it, just wanted to check and see if you could help me out or if anyone else has any suggestions. Thanks.
  • Hey, have you found the answer to this problem yet! I have the same issues with my 96'GC, I've replaced the same parts as you. I do get a trouble light from the Crank shaft position sensor. It reads out a intermitant reading of piston 1. I also have violent back fires ever so often. Think I may have to replace my PCM.
  • cpb2cpb2 Posts: 6
    not fixed yet, but I have not invested any time or money yet; hoping for forum help, too. Like yours, no check engine light or diagnostic codes are set on mine. I don't see the cam position sensor on your list. I seem to recall my problem showing up about the same time I replaced the plug wires/dist cap and rotor. That was prompted by noticing arcing from plug wires after washing engine. Problem seems to be worse in the rain. Wonder if I got something wet or damaged a weatherseal?
    Mine does not die completely like the Grand Cherokee thread recommended by the host. Will keep forum posted if I succeeed.
  • I have had a couple of problems with my jeep lately. Not sure if they are related or not. First, when starting sometimes it would sputter and miss, once i get on the road and get it enough gas it was fine. Well the other day it started and the check engine light came on. I drove it for about 15 min and the check gages light also come on, it was overheating. We changed the spark plugs and deleted the ODBII codes po300, po302, po305. Now check engine light is off and has not failed to start properly. Now it overheats at idle, the fan is on but seems to be spinning slowly. Sorry for such a long post!! Please Help!!
  • tuggajbtuggajb Posts: 646
    what engine codes are all eng misfire have you done any work on it?
    fan could be fan clutch bad
  • The code po300 is misfire on random cylinders, po302 and po305 are the number of the cylinder. The only work i have done is change spark plugs and erase those 3 codes. By the way i have the 4.0 I6. Also, it doesn't seem to overheat evertime i drive it.
  • tuggajbtuggajb Posts: 646
    fan cluch could be on again of again first thing i would change is crank pos sencer if that is not working right would throw off timing and could cause overheating and miss fires
  • cmbmbspscmbmbsps Posts: 2
    Well, I bought a 1990 Jeep Cherokee just 2 Days ago. It's Automatic Transmission, 6 Cylinder Inline Engine 4 wheel drive. The previous owner told me he had just replaced the water pump and thermostat, but didn't mention anything about an overheating problem. When We got it home I did a complete tune up, changed all the fluids and filters and such. I noticed, after the drive home, that there was water in the coolant reservoir. I figured that it was just becuase he had replaced the water pump, and thermostat, and wasn't wanting to waste coolant. After we had finished our tune up, we took it on a drive to see how it was doing. It drove just fine for 15 minutes, and started to heat up gradually until it was in the red. We pulled over, waited for a bit, and drove to a mechanic. He told us that because it was a closed system, it's very easy to get a bubble in it, and that it doesn't work to just fill up the reservoir. So, we unplugged the heat sensor in the back of the engine, and took off the main radiator hose. We filled up the Radiator with coolant, directly through the hose until we had a steady stream of coolant coming out of the back of the engine, where the heat sensor was. We than filled the reservoir up, and let her run. After about 5 minutes of idleing, the reservoir had emptied some, and so we filled it a little past half way to complete, and we figured the bubble was gone, and our overheating problems were over. a 25 minute drive around town confirmed that. However, we drove it a distance of around 65-70 miles last night to be able to get home, and it did just fine until we got about 10 to 15 miles from the destination and it started to over heat again. We pulled over, and it spued coolant all over the place. So, in the end, something's wrong. So, to finish off, just some last things I noticed..... 1.) We found a pinched radiator line that goes back to the transmission (it appears the transmission is cooled by the coolant as well???) 2.) When it gets hot, the coolant seems to bubble back into the reservoir,and is usually boiling inside the reservoir. 3.) The coolant seems to be a rusty brown color whenever it overheats. However, it was a lot less rusty the second time. I have a feeling that it is just a bad, corroded Radiator. But, I just don't know. I want to change from a closed, to an open system, and don't know I sure would appreciate any help. Thanks!!!
  • rnadeaurnadeau Posts: 1
    I am replying because I have the same problem you are talking about. I have a 2000 jeep striaght six and replaced oil sending unit and finally oil pump which was very expensive and I still have the problem. I am looking for any suggestions or solutions. I was also having a problem with loosing radiator fluid. Thanks, Rick.
  • I took mine to a dealer about a month ago. It also needed some other work, but I wanted to make sure that there was nothing seriously wrong engine wise before shelling out money for a new radiator and new battery. They were sure the problem was the sensor. So after paying $900 for the sensor, radiator, and battery I drove home only to discover the problem hadn't been fixed. When I took it back the next week they told me the problem was in the engine and quoted me $5000 to replace it, which obviously I wasn't going to do. My Solution: I'm trading it in and leasing a new Nissan XTerra. They gave me $3000 for the trade. Too bad I owe $6000. My guess is the engine they were putting in Cherokees and Grand Cherokees of this era was a complete piece of crap.
  • jeeptsijeeptsi Posts: 8
    I changed the pcm (engine control module). My mechanic advised that he got another jeep into his shop and was advised that the jeep would run if the center connection of his pcm was held up. seems that the connection would loosen up and cause the jeep to idle rough and then shut off. he advised that the circuit board in the pcm may be cracked and changed it. so far it's running great now. you can get a refurbished unit for $250- $ your local auto parts store.
  • jeeptsijeeptsi Posts: 8
    It could be any of these problems:
    1. emissions system not functioniong properly
    2. fault in the fuel or electrical systems
    3. faulty secondary ignition system (cracked sparkplug insulator or faulty plug wires)
    4. vacuum leak at the throttle body, intake manifold or vacuum hoses.
    5. valves sticking.
    6. crossed plug wires- check the firing order.
    7. valve timing incorrect.
  • jeeptsijeeptsi Posts: 8
    Try changing your crankshaft position sensor first. This senses crankshaft position (tdc) during each engine revolution. The pcm uses this information to to control ignition timing and fuel injection synchronization.
  • tuggajbtuggajb Posts: 646
    prob have pluged rad would put new one on heaveyduty

    trans has small cooler in side rad un pinch line for sure
  • tourprotourpro Posts: 1
    So I bought a 2000 grand cherokee on ebay (first mistake). IT has always run hot since I bought it about 3/4 or a little more on dash. So then one day it chimed and said check gages and it was almost on the red. I had the thermostat then we got into the water pump which was cracked. seemed to be fine after that. about 2 or 3 days later I was driving on the highway and overheated at 3/4 on the dash and the heat went cold. so I bled the cooling system to remove any air pockets, but now it still runs 3/4 or more on the highway... but in the city it runs just over 1/2. Any suggestions???? I would really appreciate any input.
  • cbeissercbeisser Posts: 1
    I have a 2000 Jeep Cherokee Sport, 93,000 miles. I had the same problem with my oil pressure; it's fine when I start up, but after driving for 5 minutes it begins to drop and will drop all the way to zero if I come to a stop. Last week I realized I was also losing coolant. Took the Jeep in for service, mechanic says I have a cracked cylinder head. This is my 3rd Jeep Cherokee, the others ran for 160,000 miles plus (my 99 is still on the road-no problems). I asked the mechanic why this Jeep engine failed since it's been carefully maintained just like my other Jeeps, he said "some of these heads just crack spontaneously". (???)
    Does this sound right to anyone?
  • If you check the forum, most of the people having this problem have Cherokees or Grand Cherokees of about the same era. Clearly, whatever engine they were putting in these vehicles was sub-standard. My last Jeep was an 1986 Cherokee Wagoneer that ran forever. It was the reason I bought another. Now, I've got a Nissan.
  • commitcommit Posts: 1
    I have an 02 and had the same problem. The engine light would come on for about a week and then go off. If you have an AutoZone near you ask them to run their system on it to give you the exact reason the light is coming on. If it says slow emissions leak, which is what mine said, you can do one of two things. One, check your emissions hoses to make sure they aren't cracked, this is really simple, just open the hood and there are only two hoses. The guys at Autozone can show you where they are just in case you're not sure. The next thing, and this is what fixed mine, was replace your gas cap. Mine had a slow leak around the gasket. Hope all works out okay.
  • acewinduacewindu Posts: 1
    I have an 05 JGC, and it shuts off while slowing down. The dealer can't figure it out, replaces O2 sensors, etc. They say they don't understand the codes the computer sends, then they bring in Detroit. They are no help either. This leads to dangerous situations while driving. They termed it Parking Lot Manuever issues. It only happens while I'm slowing down. It happened again when I turned on the AC, and it idled up and down from 0 - 600 RPMs. Any ideas?
  • I have a 2000 Cherokee Sport, 4.0L, 4x4 and have had an overheating problem since 2005. It began to overheat so I took it in...had the radiator, thermostat, and head gasket replaced. It worked good for about a year and started to overheat again, but was okay as long as I kept filling it with coolant. About two weeks ago it wouldn't run at all without overheating. Just finished replacing the head gasket, water pump, thermostat, thermostat housing (it had cracked), and the radiator. I did it myself and just finished last Saturday. It ran perfect, had put about 250 miles on it, until today, on my way home it overheated. I am at a it possible the engine is bad?? It shouldn't be running that hot, and I know there is nothing wrong with the cooling system now, I just replaced the entire thing. Any suggestions?
  • jc00jc00 Posts: 2
    My wife's 2000 cherokee 4.0L just started experiencing the issue.

    Which is strange because a co-worker just had his 2002 cherokee 4.0L have the issue fixed. He went to a dealer. They replaced the sending unit. It was good for a couple of days... then back again. The dealer then replaced the pump at the tune of $450.00+. His issue has not returned in 2 weeks. He also never experienced the engine running rough when the issue occurred.

    My wife's vehicle on the other hand was really struggling to keep idling. So, not having alot of cash, I decided to tackle the oil pump.... it is Michigan... 30 degrees and snowing in April.. NICE! I have been under the vehicle so far for about 8 hours across 3 nights. If I had a lift it probably would have taken me maybe 2 hours to get to this point. I am ready to put the new pump in.

    That being said, if it gets to the pump replacement stage with you, I would suggest paying the extra $300 to have it done for you.

    I will update this when the pump is in to say if it fixed it or not.

    At any rate.... We never had the issue until the wife took the Jeep to a Valvoline quick change. The clown over filled the engine. I am guessing two quarts. This allows the oil to be aerated by the crank. Also, to be noted we had used a semi synthetic the oil change before. So, this oil change took us from semi synthetic back to plain oil.... maybe this could pay its part in root causing this issue...

    more details to follow....

  • rllewisrllewis Posts: 2
    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.
  • cpb2cpb2 Posts: 6
    FIXED! Turns out that it was the upstream O2 sensor, even though no diagnostic codes were set. Local shop put 2 hrs labor into diagnosing it an nailed it first try! Have driven it a dozen times now with no problem whatsoever. Go for it and post confirmation!
  • tuggajbtuggajb Posts: 646
    be sure to prime pump or you will have the same prob you have now
    i just fill it with grease befor i put them on
  • I have an '05 with the same engine. I have 57,000 miles on mine and I've never had that problem. Nothing normal about that to me.
  • After I changed the PCM, all is well.The funny thing about this is the dealer ship was just as lost! Great information on Edmunds. For all who are out there with a jeep crank shaft sensor or cam sensor Problem. If after changing the sensor and you still have problems you may have to change your PCM;that fixed my problem. I didn't have any luck with having the PCM checked by the dealership. GOOD LUCK!
  • I have a 91 jeep Cherokee with the 4.0 HO it starts and idles fine then I put it in drive and after about 5 minutes of driving it will just stop running, when I stop I can crank it over and it wont start but if I turn the key off for a minute It will start and do the same thing as soon as I start to drive. Rarely when it dies and I stop the starter wont even work but the radio and lights work.
  • I have the same exact problem with my 1994 4.0 Jeep Grand Cherokee. Have you found a solution?
  • pgr40pgr40 Posts: 2
    My son just purchased a 2000 GCL 4.0L with 74K miles.
    While driving it home the temp gauge showed 240 degs.
    I checked it out and found that the fan relay is bad:
    AC engages, fan doesn't go on.
    Temp exceeds 210 deg., fan doesn't go on.
    Switched the 40 amp fuse in the PCM, fan doesn’t go on.
    Hot wired, fan goes on.
    Is the fan relay on a 2000 GCL 4.0L the same and in the same place as your 2003?
    If not do you know where it is located?
    NAPA part#?
  • 440jeep440jeep Posts: 12
    I have a friend who uses MMO and he swears by it. But my father is a die hard slick 50 guy. I was wondering about which to use in an engine I am building (all brand new parts). or is the MMO stuff just for lubing up older engines?
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