jurazov

Hey guys I'm new here and glad to be a part of this forum! Here to seek some expert advice...

Anyway, I bought my 98' XJ about a month ago with 175,000 miles. It's been running like a charm except for the first few minutes every time I start it.

Once started it idles around 800rpm for a minute, then the idle goes crazy dipping up and down and almost stalling for a few minutes. During this time it smells like gasoline and sounds like an old boat. Once its done going through this it will be fine for driving until its shut off and started again. If I try to drive it while its being funky I can barely accelerate and cant go over 2000rpm for a few minutes, then it drives normally again.

After some advice, I have cleaned the throttle body and IAC valve. Nothing has changed, anyone here ever experience a similar problem? Where should I look next? Thanks guys, much appreciated.

DeBo@64

PatHenry

DeBo, you should start your own thread rather than revive a 3 year old one.

In regard to your problem, I'd bet you jostled a vacuum line loose when you were in there or cracked an old dried out line. If there's nothing going on with the vacuum lines, I'd check your intake/exhaust bolts are tight, you might have pushed it loose while in there.
The other thing is you may have damaged your IAC valve (the little phallic shaped sensor in the TB) or the TPS.

97grand4.0

I think Dave said he cleaned his TB with spray cleaner and messed up the TPS, ..had to replace it as I recall.

Hurricane Harvey

just for future reference to anyone who reads his post. More than likely you are having idling issues because the O2 sensor (heaters) are not working. Normally the O2 sensor will heat itself up to 600-900 degrees so that it can get a more accurate oxygen reading for the engine. If the heater is out on the O2 sensor the vehicle would run like crap until it got up to operating temperature and then your symptoms would slowly dissolve away. Normally the sensor is switching back and forth from .1 volts up to .9 volts. about twice a second. .1 volts = lean mixture & .9 volts = rich. so if the O2 sensor is cold and trying to get a clear reading it will be going from lean to rich. and the idle will be jumping all over the place, smelling like fuel then smelling like a blackcat, loping.

Google Symptoms of a bad O2 Sensor. Here is your result:
Symptoms of a Bad Oxygen Sensor. When you have abad oxygen sensor, your vehicle will run less efficiently, it can sometimes have a poor idle, erratic jerking atsteady throttle, hard starting problems, cause thecheck engine light to come on, and will cause high fuel consumption.

In short. Change your 02 Sensors. Don't be cheap and clean them. they have reached temperatures of thousands of degrees, thousands of times. They play a major factor in the life of the engine, exhaust, and gas mileage. If you are driving around with bad O2 sensors the engine is not harmonic (all cylinders burning the same temp and equally powered) if you drive around with misfires you will destroy your catalytic converter. Not to mention the uneven power strokes on the engine is horrible for it.

if you can't set a glass full of water on top of a factory economy cam engine without it spilling a drop it could use a little love.

This is my first Chrysler vehicle;
1995 Grand Cherokee Limited 5.2L My first Chrysler, bought running @ an online auction $638. Oil pressure issues, changed oil pump, sending unit, oil and filter Also has Deathwobble, replace all 4 shock absorbers (had 4 different shocks all the way around?? LOL)

1990 Chevy silverado 5.7L retired at 700,000 miles
1991 Honda civic hatchback 1.5L retired at 500,000 miles
2005 Honda civic LX 1.7L sold at 320,000 miles with factory compression

Pennzoil Oil with WIX filters 4 life!!!

97grand4.0

Golly, any first time poster that swears by Pennzoil, cures death wobble with 4 shock absorbers, and fixes low oil pressure by changing an oil pump, well sir, I'm gonna take that advice.

Hurricane Harvey

lol. Simple answers for simple problems. Mitchell 1 on demand 5 is a must. I have heard a lot about oil pump problems on these Chrysler engines. So if this is my first Chrysler k let's just eliminate that off the rip

97grand4.0

Lol. do any plastiguage when you had that pan down? just wondering.

Hurricane Harvey

No I did not. had i thought about it before hand i would have ordered some.
Have my mind on all the other problems for the time being.
One thing about getting a used vehicle. "You're just buying someone elses problem"
lol

Dylan Clodgo

This post seems ages old. But i stumbled upon it and didn't see this answer. But long story short guess: Fuel Pressure Regulator--Ruptured diaphragm--Easy to test, pull small vaccuum hose off regulator located at front of fuel rail. Small hose should have suction. If gasoline pours out of regulator from where the small hose was attached, the inner diaphragm of the fuel pressure regulator is ruptured. Thus instead of the vacuum hose pulling the spring and making the PSI in the fuel rail different, the broken diaphragm is instead allowing gasoline straight into an air hose,-- routed, un-accounted for, back into the engine combustion, causing engine to run rich. When the air is warmer you get less oxygen per volume so the car essentially needs more, and this combined with the car already having too much FUEL vs air, can make the engine miss. Cold air has more oxygen combustion per capitia than hot air. Anyways, I had this same problem on my 1997 chevy cavalier, in PHX Arizona, it would idle and run like **** in the scorching daytime 90-110F temps. But run good at the cool 65-90 night time temps. Finally filmed engine starting it and saw the gas squirting from the vacuum hose, which had melted against the engine. Lol, hope this helps. NOTE: I have a 1995 Jeep Xj and it also has a fuel pressure regulator. I don't think they're featured on the 1996 and up versions though. Maybe slap a fuel pressure gauge on there to check for 39 PSI with vacuum hose detached and 31 without on 1995 xj.

SilverfoxXJ

a
sounds stupid I know but check temp sender in t/stat housing? It is known to send a "cold" signal and tricks the PCM into shutting down? ALSO CHECK O2 SENSOR WIRES FOR SHORTING ON DRIVESHAFTS OR EXHAUST MANIFOLD?

TrailerTrash

jakeepoo3

I came across this also and would like to say this post is accurate except for one detail you didn't think about. The PCM is in open loop mode during warm up cycle therefore ignoring o2s until operating temperature is reached. That's why his idle was on point until the truck warmed up and began monitoring o2s..