HELP! Idle problems!!!

[hmrdwn88lx]

I have an 88 lx 5.0. I am having some idle difficulties and it doesn't appear to directly be the iac. I can let it sit in my drive way and it will sit there and purr just find, usually. But about 80% of the time while im driving down the road, idle will just surge up to between 2000 and 3000 rpm and stay their until I turn the vehicle off. I can stop and turn the car off and back on and idle will return to normal, at least initially. I have stopped when this has happened and left the engine running, gotten out and disconnected the IAC during one of these surging episodes. And the idle goes back to normal. I plug it back in, and the idle goes crazy again. This led me to believe that the IAC was bad, but I have gone through 3 new IAC's, and it makes no difference. Obviously something is sending the IAC incorrect signals. I have ABSOLUTELY no clue as to what it is. If anyone out there can help, I'd really appreciate it. Thanks.

 

[jrichker]

See "Help me create the Surging Idle Checklist" at http://forums.stangnet.com/showthread.php?t=534062
for help with your idle problems. The first post contains all the updates to the fixes. I continue to update it as more people post fixes or ask questions.

 

[HISSIN50]

Though it sounds like an IAC issue, if not:

A tip from Jrichker is that this is a sign of a bad TPS (carbon breakdown in the wiper, or something to that effect). The idle will run-up and hang. The fix is to restart the car and it will be ok till it hangs up again.

The IAC seems likely, but just in case...........

Good luck.

EDIT: He beat me anyhow.

 

[hmrdwn88lx]

thanks

thanks for the input. Im gonna try the checklist, for right now though, I have just unplugged the IAC and manually ran the idle up just a little so its driveable. Rides great like that, but Im not the "unplug it and forget it type" i wanna fix the problem. thanks.