bonesxj
NAXJA Forum User
- Location
- running springs,ca
After starting my 89 XJ, some times the RPM's go up to 2000 and stay. I have to turn it off and on a few times before the RPM's go back to normal at idle. Any thoughts...
I would agree with the IAC. My '89 does that too...especially with cold starts when it's cold outside (less than 20 degrees). After it finally idles normal, it won't do it again until the next cold day/cold start.
Cleaning the IAC helps for a while, but so far hasn't seemed to be a permanent fix...might have to spring for a new one!
Also, be sure to check for vacuum leaks...sometimes cold rubber doesn't seal so good and a leak will cause the high idle.
Our 89 MJ does this as well. I have a new IAC and shut down relay(sets the IAC for the next start). I have a new MAT and CTS. There are no vac leaks.
It still does this. I'm starting to think its a trait of the 89 ECU.
Mike, my 89 only revs high on start up then levels off to a smooth normal idle. It acts as if its setting the IAC too lean but it starts great and much faster(less turns) than my 90. It starts quick like a HO but just has the high rev.
Check the fuel pressure regulator's vacuum line for any gasoline, maybe an early small leak. Also could be an injector with a slow small leak. Only way I know to check that is a fuel pressure gauge, leak down test, after turning off the jeep, to see if pressure holds or drops.
We get so use to the usual suspects (ground isues and vacuum leaks) we sometimes forget the unusual ones. Yours could be excess gas sitting around at start up.