jeepster_259
NAXJA Forum User
- Location
- West Palm Beach, FL
98 xj classic, auto, 4.0.
So, I went out wheelin' today to take the jeep out and test run it since it had been about a month or so since I'd really driven it. Didn't beat on it too hard, but went through some mild water and got stuck in some mud up to top of the 33" tires a couple times.
Before going out today, I made the following repairs over the past month:
180* thermostat
new e-fan
new brake shoes, pads, calipers, rotors
new oil pressure sender
radiator flush
Also, upstream o2 sensor is bad so I had left it unplugged for the past 100 miles or so. when plugged in the jeep idles like crap and carbon comes out the tailpipe. When unplugged, it runs fine.
Anyway, with that background, I can't figure out what the issue is. Halfway through wheelin' today, the jeep starts to buck and surge in all rpm ranges and backfires in the manifold. At idle, it will drop down to 200 rpm, almost stall, then shoot up to 1500 rpm. With my foot on the gas steady it will spike and drop about 750-1000 rpm every couple of seconds. After shutting the jeep down for about 15 min. while we ate, the jeep was fine and made it out of the trail w/o an issue. While driving home, it started again. Stopped at parts store to pick up a few parts (shut down for about 10 min.). Jeep ran fine the rest of the way home.
Got home, was washing off jeep with it idling, started doing it again. Went to parts store, tried replacing TPS, IAC, and MAP sensor. Nothing. I thought it was the IAC at first b/c when I tapped on the old one while the jeep was running, the surging would stop for a minute or so. Put in a new one, still surging. Cleaned old one, put back in, still surging.
Any ideas??????
So, I went out wheelin' today to take the jeep out and test run it since it had been about a month or so since I'd really driven it. Didn't beat on it too hard, but went through some mild water and got stuck in some mud up to top of the 33" tires a couple times.
Before going out today, I made the following repairs over the past month:
180* thermostat
new e-fan
new brake shoes, pads, calipers, rotors
new oil pressure sender
radiator flush
Also, upstream o2 sensor is bad so I had left it unplugged for the past 100 miles or so. when plugged in the jeep idles like crap and carbon comes out the tailpipe. When unplugged, it runs fine.
Anyway, with that background, I can't figure out what the issue is. Halfway through wheelin' today, the jeep starts to buck and surge in all rpm ranges and backfires in the manifold. At idle, it will drop down to 200 rpm, almost stall, then shoot up to 1500 rpm. With my foot on the gas steady it will spike and drop about 750-1000 rpm every couple of seconds. After shutting the jeep down for about 15 min. while we ate, the jeep was fine and made it out of the trail w/o an issue. While driving home, it started again. Stopped at parts store to pick up a few parts (shut down for about 10 min.). Jeep ran fine the rest of the way home.
Got home, was washing off jeep with it idling, started doing it again. Went to parts store, tried replacing TPS, IAC, and MAP sensor. Nothing. I thought it was the IAC at first b/c when I tapped on the old one while the jeep was running, the surging would stop for a minute or so. Put in a new one, still surging. Cleaned old one, put back in, still surging.
Any ideas??????
Last edited: