Diagnostic Gurus, 1998 Jeep Grand Cherokee problem

Discussion in 'Other Auto Tech' started by GreenStangGT, Jan 5, 2008.

  1. While this isn't a Mustang related car problem (thank God), it has me at my wits end and I would appreciate any advice I can get. As such I am offering a $20 reward for the first person would can correctly diagnose the problems I have been having with my 1998 Jeep Grand Cherokee. I will be glad to send you the money via PayPal or Money Order.

    Most of the time (but not always) the Jeep starts up fine. Occassionally, like tonight, the Jeep won't start. Sometimes it takes as long as twenty minutes before it will start.

    Once I am driving down the road, the Jeep often sputters and dies. It is especially likely that it will cough and die when the RPM's are low, such as at idle. Sometimes it will die when the RPM's are high, though. Recently I have noticed that when I start the Jeep back up immediately after it died the headlights go off for about 1-2 seconds. This may or may not be relevant.

    Now for some of the really weird stuff. Many times I will be driving down the road and the Jeep will act as though it died, but still will be technically on. What I mean is that everything works properly, such as lights, radio, power steering, etc., but the accelerator won't correlate to speeding up. Pushing the pedal may result in the RPM's going up, but the cars speed won't increase. At this point the Jeep may die or may suddenly come back to life. Sometimes in the middle of this process, during the period where the car seems like it's sleeping, it will backfire heavily throughout the exhaust. Once it backfired so much and so explosively that it took the muffler with it.

    This started happening about a year ago, and since then we have done many things in an attempt to fix the issue. We first replaced the computer because it died one day and refused to restart for anything. Replacing the computer resulted in the Jeep returning to its normal bad behaviors. Then we replaced the coil, which for some odd reason seemed to fix the problem for a while, but after a month or so it came back. Then we replaced the ignition module because it locked up. We have replaced the fuel pump also, as well as several sensors including the crank shaft position sensor (yesterday). Nonetheless the problem persists and I am at my wit's end. Any ideas are more than welcome! Trust me, I'd love to send you $20 if it would lead me to a correct diagnosis!
  2. Moved to Other Auto Tech.
  3. Okay, thanks for moving it. Any advice would still be appreciated!
  4. Well, I guess it was worth a shot. Thanks anyway.
  5. Old thread, I know...

    Id find a way to test the MAP (manifold absolute pressure) sensor to see if its within spec. As well as the IAC (idle air control) valve, and maybe even the TPS (throttle position sensor).

    That really sounds like a PITA problem!!!
  6. yo did you ever find the problem to that cuz my car been doing that for about 6 months now