is there any other way to lower idle speed, besides of vacuum leaks? I have plug al manifold ports with no change, I vacum all lines off of manifold found one small leak all held vacuum. I changed the egr, idle control valve, throttle sensor. I sprayed with wd40 and with water no change. idles 2000 cold the 1500 hot. I read you can change with the idle control valve? checked brake line good has no cruise control what am I missing?

If the engine doesn't stall with your finger covering the IAC port (and throttle closed), you've got a massive vacuum leak... and/or possibly someone has messed with the idle stop screw. (There should be a "plug" covering/hiding the head of this screw.) To take the idle stop screw out of the equation, cover the entire opening to the throttle body with the palm of your hand while the engine is running. If the engine still runs, there is definitely a huge vacuum leak.

[This message has been edited by Patrick (edited 03-22-2021).]

Does your fiero have cruise control? if so, the module has the cruise control throttle cable, which can be adjusted through 5 different holes. mine had the same problem. i put the cruise control cable on the outermost hole, and it idles at 1200 warm and 1500 cold. (they usually have retainer clips on them, check for that) (credit to 2002z28ssconv for the photo on a post here from 10 years ago) EDIT: also yes i know that picture is of a 2.5 L4 cruise control, but the 2.8 V6 is in the same place.

[This message has been edited by 86fierorestoproject (edited 03-27-2021).]

Pull off spark plug wires one at a time until you get to the target idle speed.

HA HA?

A common cause of a high idle is a broken EGR valve pipe/line. They are made of a thin steel and do break.

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THANKS. got idle around 800 at coil. tack said 1200?? so good now

Which solution ended up working for you?

quote Originally posted by michael jatcko: THANKS. got idle around 800 at coil. tack said 1200?? so good now

Curious, I'm eager to know just how many wires did you pull before you got to 800 rpm?

Spoon

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