Rough Idle...Can't reset base....help

extremetrek · Aug 16, 2005

Howdy....again,

Well, it seems that I am on here over and over again for one problem after another. This time its a rough idle. As I stated before the idle on my car is rough, shaking and lurching at a stop and making pulsing noises, at about 600 rpm. I was running through the four steps listed in other posts, I cleaned the IAC, cleaned the throttle body, and went to change the base idle. The article says to disconnect the batter, disconnect the IAC plug, reconnect the battery, start the car and then reset the idle with the idle screw. The problem is the car WILL NOT start without the IAC plug, plugged in. If I unplug it it will stall the engine EVERY TIME. I changed the cap and rotor, and checked the plugs it all looks good (although a wire and plug swap are within a few days).

I tried to simply twist the screw but the idle DOESN'T change at all, so is there another way to adjust the idle? The plug I was unplugging the one that goes into the top of the IAC, is this the correct one? Once the car is moving she runs very well no missing or even a hiccup just the extremely rough idle.

One more time my stangnet brothers (and sisters?) my car needs you!

Thanks a lot!

HISSIN50 · Aug 16, 2005

John, are you doing the disco'ing with a hot motor? The motor needs the IAC to idle when cold.

Good luck.

extremetrek · Aug 17, 2005

Well I was doing it when it had been running for at least ~30 minutes prior to that. Guess it could have been still a little cool, though somehow I doubt it. I will try again in the morning, run it around and then let it idle for awhile to get the temp up a bit, thanks for the advice. BTW, is 800 rpm the accepted base value?

R.J. · Aug 17, 2005

Try adjusting it this way:

MECHANICAL IDLE SETTING

'94-'95

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.

R.J. · Oct 26, 2005

Did you ever get your car to idle?!!!

Rough Idle...Can't reset base....help

extremetrek

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Rough Idle...Can't reset base....help

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