• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

High Idle

hjeepxj

#OCDINK
NAXJA Member
Location
Denver, CO
I am getting the occasional high idle, 2k in P and N and then 1200 in D.

It is random, and it goes away.


I have replaced my CPS and IAC sensor.

What could it be?

TIA
 
High idle on a Renix based system normally means you have a vacuum leak.
 
I think some or maybe all of the '88s have the C101 connector. I had similar problems on my '87 and cleaning each of the contacts in this connector was the cure.
 
I did you one better. I cut out the connector and spliced all the wires together. There was a factory update about problems on that connector and that is what they recommended. Just be sure and do a good job. In other words solder and heat shrink. Crimped connectors by themselves will leave you high and dry in a year or two.
 
I have a low idle in my 88 laredo. Just got a motor vac done which cleans the engine. It starts without pumping gas now with the cleaning, but still low idle. Sensor?
 
High idle can be a number of things, but has always been a sign of a failing Throttle Position Sensor on my 1990 with 4.0 engine. If it comes and goes, then it is more likely an electrical fault like the TPS sensor than a vacuum leak (which should be more constant). If you have an automatic transmission, then you may also notice some weird shifting (timing off), since the TPS also gives a signal to the auto tranny. My 1990 is on its third TPS in 206,000 km/128,000 miles. For years up to 1990, the TPS is adjustable, and must be set to specification. Try a search here for TPS for the procedure (requires a multimeter and a couple of big pins to stick into the back of the connector to make contact for the meter- adjust it with everything connected). 4xBob
 
Ditto on the tps or its connector going south. Random high idle usually at startup classic symptom per my jeep tech. New tps cured mine of this. Vacum leak high idle tends to be consistent under set conditions. E.g. my idle goes up couple hundred rpm when warmed up when my intake manifold bolts get a little lose. Greg
 
TPS is the next sensor to replace! :agree:

Thanks! :)
 
I had the same problem in my 87. I replaced the TPS, Idle/air sensor, you name it I tried it.....nothing. Spent lots of money....Feeling like an idiot, I started to tighten everything down. When I hit the bolts by the firewall on the intake manifold. They were all loooooooooose!!! tightened them down, and never had a problem. Do the things that dont cost anything first.....you'll thank yourself in the end, instead of kicking yourself in the "end"......WinMag
 
What about a sticking idle motor. Yelp that did it for my 1990. It is two screws and goes into the throttle body. You might even be able to clean it. It does control the idle rpm and it does go bad...................


james
geocities.com/jammerjamesharmon
 
Back
Top