I have a xj 2.5 with a strange idle issue. When I put it in revers it it flys. 1st and 2nd gear run with no gas needed but slower then revers. About 8 mph for 1st and 17 mph for 2nd. But no idle on 3rd 4th and 5th. New map sensor new tps and new distributor. I'm thinking distributor Is too advanced or there is a sensor out. I changed the manifold gasket fixed high idle in all gears but still acts like there is a vacuum leak or excel orator is running high. Any one had this problem?

 

I appreciate the picture, but you're showing me a pic of the Idle Air Control Valve. Not the TPS...???

The IAC is brand new, the TPS is brand new, and I have cleaned the Throttle Body so well I could probably sell it as a brand new part.

I just this morning took off the TPS and went up to Advance to exchange it for a new one just to see if perhaps I received a defective one. And to my surprise it solved my problems. In fact it ran so well, I thought I was driving a brand new car of the showroom floor. I drove it around a lot, stopped and re-started my vehicle several times without incident. Until just now, after letting it cool down for a while Im back to having all the same issues as before.

As soon as I can scrape up an extra $109.00 Im going straight to Jeep for a genuine TPS. If that fixes me up I'll be going back to Advance for a full refund.

 

Probably not the TPS.

 

Went to Jeep this morning and purchased a genuine Mopar TPS.

No change at all... :/

 

My 90 with just the one forward 02 sensor, the idle would cycle about every 20 secs. It would slow, stumble, nearly die, then surge up for a second, then repeat.

For wholly different reasons, (slow to heat up, bad mileage and a very sooty tailpipe), I changed the 02 sensor. Bingo, idles smooth. Come to find out from Cruiser, he'd heard of that before. Was a nice surprise bonus for me!

The 87-90 is different in lot's of ways, but they may well share that. Also the 02 is so important for mileage, it may pay for it's self. I don't think it throws a code unless the wiring (or heater relay) is messed up.

 

Im not throwing an 02 code...

 

I dont know if you still watch this post, but I have an 87 with that exact issue and have not been able to findanything about it. I know if my motor is stock or from a newer jeep. 4.0. Runs great other than that but whatever is causing it is killing my gas milage. But I did buy a new o2 sensor and it didnt help. I have also changed some of the other sensors from used ones from other jeeps trying to get some sort of difference but so far nothing. And until i saw your post about yr 90 i havent found anything else describing it. I even changed the computer. Nothing. No change. Still have that bogging and crap milage. I too only have the foreward o2 sensor. I have checked my vaccum lines the best I can so far. Everything seems in order. I have tried to clean the Iac sensor. And tried to adjust the tps. Im no master mechanic but like i said. I have yet to alter, eliminate, or make worse that damn bogging. Not sure where to look next without spending $50 or more per new sensors.

 

Check out cruiser54.com Pete is also active here on this forum. There is so much with the wiring, especially 87-88 with the C101 connector. Your $ on the new 02 sensor likely was not wasted, it's nice to know at least that is OK. If y0o9u start a new thread with 87 in the title Cruiser will likely find you. WELCOME! and good luck.

 

I would clean the throttle body first anyway if that hasn't been done. Check the line to the MAP sensor to make sure it's not cracked. I had the same issue. Changed the O2 sensor. I have an old Snap-On brick scan tool that showed the computer going into closed loop / open loop as it tried to warm up and the O2 sensor wasn't changing quickly enough. New O2 sensor and it was a brand new vehicle.

 

old thread got me again!