Renix Idle, untill a difinivitive solution is deternined...

I have replaced the TPS, IAC and MAP sensors. All of which seemed to correct this issue. If only briefly.
Go figure, An F150 fan, drove my `88 Pioneer and almost ran it through his fence. He started it up and the idle would not stop climbing. Major issue on icy roads!!!
While the engine was going insane, he turned the ingition switch to the "OFF" position and returned to the "ON" possition quick enough so the engine did not shut down. Doing so, the idle dropped to safe and relaxed RPM. I have used this technique three times since, successfully.
What would cause the Idle adjustment by briefly disengaging , then re-engaging the ignition switch?

Have you checked or replaced the Relay for the IAC? When you had the IAC off, did you clean up the throttle body? You were also able to adjust the TPS correctly?

Also have you checked and cleaned up your grounds??

Definetly sounds like a sticky IAC / IAC relay, bad ground ... or a mis-adjusted TPS.

luvme88xj said:

While the engine was going insane, he turned the ingition switch to the "OFF" position and returned to the "ON" possition quick enough so the engine did not shut down. Doing so, the idle dropped to safe and relaxed RPM. I have used this technique three times since, successfully.
What would cause the Idle adjustment by briefly disengaging , then re-engaging the ignition switch?

Click to expand...

what would cause it? the same reaction of shutting of and restarting the engine- even though he cycled the igniton switch fast enough to not stall it, the computer knew it was off-

Idles that climb are either IAC or vacuum leak related on all the ones Ive played with-there was a recall- something about the TPS on 5speeds running wild-

Not to jack the thread, but my '90 XJ does the same thing but only when it gets below 40 degrees. The idle will slowly rise until it hovers between 1500 and 2300 rpm. Turning it off then back on will drop the rpm for about a minute then it will creep back up.

either dirty IAC or tps issue.

when the IAC doesnt function properly idle can go up to 1200rpm or so.

when i had the idle go crazy(3000rpm) on my 89 5sp, it was do to a wet tps. dried it out and readjusted to spec with volt meter and everything was fine

ahh thanks Ed in North Ga, good call. Definetly check out your vacuum lines as well. Just one little vacuum leak can cause this.

ive rever had a vacuum leak raise the idle over 2000rpm. i would say a vacuum leak will cause an idle to do up a couple hundred rpm but not the 2500 range and not gradually.

sticky iac.....do your key trick to get the rpm to settle,jump out while its still running and unplug the iac.This will cause the iac to be set at the idle position.If the problem goes away then its the iac.....
I've had mine disco'd for a few years now and dont miss it.....my rpms don't shoot up to 2000 rpms upon starting anymore either.Iac are not necessesary on these rigs.Only thing you have to get used to is when you start it in the morning or whatever the rpms will ber a little low because the iac is disconnected so you have to give just a little gas.After the engine is warm the rpm is normal upon start up.

Check the emission tube at the connection of the large tubes in front (on the tower that hold the fuel line). Min was pulled apart and did the exact same thing. Reconnecting fixed it.

Just one of those "easy over sight" things to check

Muad'Dib said:

Have you checked or replaced the Relay for the IAC?...

Click to expand...

IAC relay doesn't trigger for 3 seconds after shutting off the ignition. at which point the IAC closes fully and re-opens at restart. i doubt he rolls along for 3 seconds at speed on the ice with the engine off, if so it's a long 3 seconds.

i've got the same problem, and if you search here you'll find that numerous older xj's (read RENIX) have this exact same issue.

so it aint the "catch all", aka vacuum leak...

mine runs like crap right up to EXACTLY 3000rpm where it comes on like a light switch and runs sweet, pulling hard and purring like a kitten. much like the light switch on my wall, it's an electric thing.

gonna try probing the ECU connector to see what's sending signals before i go spending hundreds on sensors only to not fix the problem, like so many guys have here.

stupid renix.

<--- loves renix.

understands its not a "stupid renix" thing, because Ive never had a problem fixing them, unfortunatly the people who fix them dont visit the OEM forum often enough-

renix should be spelled "SIMPLE".

voltmeter-ohmsmeter-vac/pressure gague and a few screwdrivers....its all you need. Try that with anything above a renix.:laugh2: