koledaev

Ok so I have had this Jeep for about 2 years. Ever since I have had it an emissions maintenance light has always been illuminated on the left side of the dash. I was running decently fine until recently. It now for some reason idles real rough. It's almost like the engine is heavily breathing. It will get up to about 1,000 rpm and then almost stall out in a matter of seconds. But then when you step on the gas it runs fine. Also when the engine warms up it tends to stall easier. If I let off the gas at any normal driving speeds it will stall about half of the time. Then I have to coast to a stop put it in park then start it again. I'm thinking it has something to do with the exhaust system but I'm not sure. Also the exhaust is really foul smelling. Any help would be appreciated.
http://i276.photobucket.com/albums/k...v/STA71477.jpg

XJ Stryker

Nice Jeep need to lose the visor bill though.

Would suggest cleaning and seafoaming the throttle body to clean it out. check all your Air lines. May be clogged especially the one from the back of the valve cover.

Then I would check your fuel pressure at the rail make sure you are getting good pressure. If so when was the last time the filter was changed on this 90?

If no luck there then you more than likely need to adjust or replace your TPS (throttle position sensor).

There are more ideas here but these are the most common issues with rough idle renix era jeeps.

I may have forgotten one but I would still take these steps first if it was mine.

whowey

One thing.... the emissions light has literally nothing to do with your problem what-so-ever.

It's simply a timer that automatically goes off when your Jeep hits 80k or a multiple there of.

BlueXJ

Also check the O2 sensor. It may need replacing. Check it with a meter first though. Don't go just swapping parts. That is expensive and usually not needed.

okcjeeper

Also I know this sounds stupid but check the oil for water and the head gasket for cracks or leaks..Also might go rent a compression checker from the local parts house..I had a car once an old nissan that did something very similar and and long story short it was a blown head gasket..

okcjeeper

Blue is right part swapping costs money..I did that on my motor swap and it ended up being a simple mistake of the damn distrib being off ...cost me almost 200 in parts that I probably didn't need but oh well I have a ton of new sensors..

biztyke

i would suggest cleaning out the throttle body, and unbolt the IAC(idle air control) valve and give that a really good cleaning. very often these get gummed up with carbon, get stuck at either low or high when the computer is trying to adjust idle. if cleaning doesnt fix it, try replacing it(mine was like this, and needed a new IAC). ill also second replacing the fuel filter if it hasnt been changed in a while.

big*blue*cherokee*

Nice looking rig. Hard to find older XJs that look that clean and well kept. Also, this is kind of off topic but if you're thinking about upgrading the exhaust do it while you're fixing the O2 sensor (If you have to). Kinda nice to knock out two projects at once. I agree with Stryker about the visor, not because it looks bad but it's a PITA to have to clean mud out of it after ya go muddin or something. But in the end it's your jeep, do with it as you wish.

BlueXJ

This problem has been bugging me all night long and I think you should check exhaust flow. Cat may be stopped up. Would bear checking while you are at it. Wish it was here. Much harder to check a vehicle on the internet than right in front of you.

wicked_xj

check throttle body's hoses the little one did that to me

Howler_GT

Pull CODES from computer.

Check out: http://go.jeep-xj.info/HowtoECUcodes.htm

Very helpful to know what that light is actually lit for.

Howler_GT

BlueXJ

He said it's a '90 thus it's a Renix the ECU does not store codes. No port to plug a reader into and no CEL flashes to count. Year too old for that stuff Howler.

Howler_GT

My bad. They require the Chrysler DRB-II diagnostic tool.
Nevermind.

Well, it may not help him but it is useful for anyone reading the thread.

Howler_GT

ColoradoJeepXJ

It sounds to me like your cat may be clogging.

BlueXJ

That's two of us that are thinking cat. So check it and let us know what you found.