Argh....Stupid Idle issue

[1988WHTGT]

Ok, I went through the surging idle checklist. I've tried everything. On a cold start, the car starts up fine and then idles down after a couple of minutes. On a hot start, the car won't start if I don't push the gas pedal down. Then when it does start, the idle jumps between about 600 rpm and 2000 rpm. Once it gets over all of that (or I sit and rev it until it goes away, ha), the car will not idle below about 1100 rpm. Also, if I'm driving along and come to a stop sign or red light, as soon as I push the clutch in from cruising speed, the idle drops a lot and sometimes the car just cuts off. What can I do besides going and getting it tuned! Its driving me crazy and its embarrassing!

Oh, mods are in my sig!

 

[RumbleFox]

Looks like ya got a pretty solid little Street/Stripper there

Try rebuilding, or if you wanna be absolutely sure, replacing your IAC, that thing can be hell on EFI motors if its malfunctioning. They're relatively cheap, too.

Also, check the wiring from the IAC to the EEC, might be a pain in the ass, but worth it in making sure the car's copacetic.




































Why do you think I love carburetor's so much

 

[betke76]

it is the idle air control on the throttle body, try taking it off to clean it but hold it upright so no brakeclean gets in the electronics part, if it doesn't work then replace it. that will fix it !

 

[Mike in Texas]

Idle

If you went through the checklist you probably covered this but here's what corrected mine.

Set base idle (make sure car is warmed up and the SPOUT is out) with your mods I'd say set it at ~900 rpms. Check the TPS and set voltage at .98v with car on not running. Install SPOut and check TPS at idle, should still be ~ .98v. Disconnect the battery for 20 minutes or more and then reconnect and start-up to let the computer adjust. Drive it around and let the computer make any more adjustments. If it is till surging check the other things that can go wrong, IAC, MAF, vacuum leaks, etc.

 

[5.0Torx]

yeah i would replace the IAC

 

[1987stangman]

If you went through the checklist you probably covered this but here's what corrected mine.

Set base idle (make sure car is warmed up and the SPOUT is out) with your mods I'd say set it at ~900 rpms. Check the TPS and set voltage at .98v with car on not running. Install SPOut and check TPS at idle, should still be ~ .98v. Disconnect the battery for 20 minutes or more and then reconnect and start-up to let the computer adjust. Drive it around and let the computer make any more adjustments. If it is till surging check the other things that can go wrong, IAC, MAF, vacuum leaks, etc.

Great post! I would pull the spout and then set base timing to desired number with a timing light and then unplug the IAC. The car will most certainly die but that is when you need to adjust the idle stop screw on the throttle body. Basicly you need to adjust this screw so that the car will idle without the IAC hooked up WITH the spout removed. Get it to idle as low as possible to keep the car running this way and then reconnect the IAC wire and then readjust the timing to acheive the smoothest idle. Reconnect the spout and check the idle.