Idle Reset Question...Hmmm

[MysticKeith50]

As some of you know, I did the H/C/I with everything in sig this weekend. Everything is fine, but when I start the engine when it is cold, it hunts for an idle for like 30 secs, in that time i have to give it a little gas to keep it running, after it finds the idle, it runs great. I can drive around, even if I shut it off and start it an hour later its fine, it just seems to happen when it is cold. I have the sct chip with my whole combo. We have the timing at like 10 degrees, is there something you have to do to like reset the idle(a process). Just curious.

Thanks

 

[S/CBlack95GT]

When the engine is warm and running unplug the IAC and see if it dies. If it does turn the throttle plate stop screw one full round on the passenger side of the TB. That will crack open the throttle manually so it will stay running when you first fire it. It will not do much for the hunting idle though, that's a product of the cam. After you do this you may need to reset the TPS to .98, but it's not a big deal.

 

[HISSIN50]

In addition to Shaun's wise thoughts:

Have you cleaned the IAC recently? It can help.

You can also adjust the idle setting with the idle bleed on the front of the IAC. In my experience, if you get around 1.75 turns out (or more), you start to get vacuum leak-like symptoms. I adjust the idle with the stop screw like Shaun does, but the bleed is an option for fine tuning (that wont affect the TPS).

I would retrieve codes. If you are not getting an IAC or limit code, the IAC should be able to open up a little to help. But you realize that if you help it (press the gas lightly) it doesnt realize that something is really wrong, so it doesnt adapt. If it sees that it is on the verge of stalling, or stalls a few times, it can try to adapt (so long as the issue is correctable via the adaptive strategy).

Good luck.

 

[R.J.]

A friend of mine had the same problem after a TFS H/C/I. Resetting his idle like this, fixed the problem:

Begin with a cold vehicle. The idea here is to get the car to a firm cold idle with enough air bleed capacity left in the idle circuit for IAC adjustment.

The idle stop should be set first. Back out the idle stop screw, away from the bell crank arm, until about 1/2 turn past the point where it no longer makes contact (blade fully closed). Using a 0.010" feeler gauge, tighten until gauge just drags between screw and bell crank arm. Remove feeler gauge. Tighten screw exactly 1 1/2 turns. If the screw is very loose, put a drop of loc-tite or silicone on it, so it doesn't work out of adjustment.

Now remove the connector to the Idle Air Controller (IAC) just on the other side of the throttle body. Start the car and allow vehicle to warm for 2 minutes. Give a small "blip" to let it settle. If it is having a hard time staying running you may have to get an assistant until you can get to the front of the car. Now open or close the air bleed screw (CCW opens) next to the IAC until the car idles at 575 to 600 rpm. For guys with aftermarket cams and an EEC tuner, you might want to idle a bit more briskly, say 650 to 675.

Obviously, this rpm range is by what the car and driver wants...IE, no set idle speed, whatever works for YOU.

Turn off the car. Now count the number of turns clockwise to close on the idle air bleed screw. If it falls between 1/2 and 2, it's okay, now reverse it out the same number of turns. Log the number somewhere in case you need it for the future. Reconnect the IAC. You are done.

If the air bleed screw is above 2 turns, it's a good idea to tighten the idle stop screw another 1/2 turn, and then repeat the idle setting. If it is below 1/2 turn, then loosen the idle stop screw by 1/4 to 1/2 a turn, and repeat the idle setting. Be sure to put another drop of silicone RTV on the stop screw if it was disturbed. Reconnect the IAC. You are done.
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