Car Tech forum: 98' Jeep Grand Cherokee-stalls and jerks when running, help!

I noticed that you had the same problem where your Jeep would stall and Aamco talked you into a rebuilt tranny. You then said you are still having the same problem...... duh... sounds like Aamco took advantage of you and conned another unsuspecting soul. Take your car back to them and demand your money back..... it wont do any good but it might make you feel better. Isn't it funny no sad that you take your car that probably has some sort of electrical issue to a transmission shop and they tell you that your problem lies within the transmission and yep you need a new one. Please please please get a second opinion especially when it comes to major bucks as in a new or rebuilt transmission.

Stalling is RARELY due to an automatic transmission. Anyone telling you otherwise is either trying to sell you a tranny or doesnt know what they are doing. The transmission does not lock up to the engine until it is doing over 35 MPH, prior to that speed the torque converter is strictly fluidicly linked to the engine. if it is locking up before that it is electronic control ot the torque converter malfunctioning. The torque converter is the automatic equivalent of the clutch, and NOT the transmision. These issues that you two gentlemen are reporting are most likely PCM (power train control module) issues as it controls the entire driveline function from the voltage regulator to the shift points of the transmission.

Before you go changing all kinds of sensors, pick up some heavy duty 24" zip ties. Clean the inside of the pins and the contacts on the PCM with DeOxit G5. Wrap the zipties around the back of the PCM and cross vertically over the connectors and cinch down tight. You'll notice the connectors no longer move in the sockets.

Even if it is not your problem, it's cheap insurance.

I have a 98 jeep grand limited 5.9L.I am having the same problems with mine.i took it to a friends house that has a scanner and it was saying there was a cylinder 3 misfire.i had changed the spark plus not to long ago but i got the firing order and sure enough the spark plug on #3 was red looking and looked a little burnt.replaced and it ran good,then it happened again.same spark plug,its a temp fix but there is a deeper problem,still looking for it.will post when i find it.

jay

On another thread, one member had a stall problem and said that if a dealer analysis of $109, they believed it might be the MAP sensor: about $70 and a quick 5 minute replacement that you can do yourself. Then you allow a few minutes of vehicle running to allow it to adjust to the new sensor and then no more problems. Hopefully, this might be your solution and when you read about the MAP sensor - it's on the manifold - it might very well be the culprit. Or the IAT sensor - the intake air temp sensor. Just a couple things for your car people to think about.

Also, forgot to mention that it recently had a new exhaust system new cat and all, so I know it is not the cat as the dealer suggested. had problem before and after the new system so I don't think its that. They cannot recreate the problem, I am going to have to bring the car to mechanic on the next coldest rainyest day we have

You have a catalytic converter issue. it may have a leak and the O2 sensor is reading a bad oxygen level and throwing the PCM into the default mode, causing an excessively rich condition which will cause the sulfer smell to get worse, (the 98 is notorious for this) your O2 sensor on the cat may be bad BUT dont be suprised if it isnt. the harness/connector to it are known to go bad as well. so get a service book such as a haynes from the library for info on how to check the sensor and connector and then check the harness id the connector shows bad... if both show good, CAREFULLY CUT the cat out and put in a TEMPORARY bypass tube with a jury rigged fitting for the O2 sensor (a hole cut in the pipe to fit the sensor with no leaks, NO SEALANTS!) and see what happens. if this corrects the condition your cat has gone bad or is blocked. Some people have had good luck cleaning them with steam, hot water being flushed through, acetone being misted onto the monolith and other carbon removal techniques, instead of just buying a new one online for between 150 to 250 dollars.

You noted that you did the tie wraps but did you use the deoxit? ad is the PCM getting a proper ground as well? these are two major points that need to be ensured.

Something is inducing PCM issues, either the PCM itself is bad or you have a bad sensor/ mechanical issue such as a bad cat. As for the big buck test equipment? believe it or not a 200 dollar OBDII unit will probably tell you where the REAL issue is. plug it in and drive it with it connected. when the problem happens it will be there to read it. that big buck big box cant do that. (OBDII readers are available for less tha 70 bucks on up to 500, some are even just programs and interfaces for your laptop, whatever type you get, makesure it has a plain english display not just a numeric error code read out)

I posted my same problem as you a few posts down... after about 9 months of changing parts, major tune up new computer, tie wrapping the computer, other new parts... mega $$$ still had stall problem which was worse in the rain, it started as yours, would stall at idle then when restarted it was or seemed fine... but it worsened, really bad in the rain, when driving, I suspect some kind of electrical problem, but no one could fix.... I'm now driving a Honda... sorry I gave up and got rid of the car.