Hello all. The idle on my friends 87GT automatic likes to hunt and sometimes stall when in park or at a stop sign. I've cleaned the IAC, throttle body and verified no vac. leaks.

What I found is that at idle, the TPS voltage is at .77! I know it's suppose to be around .4. The TPS tests ok tho.

It was suggested that I adjust the minimum air rate by adjusting the throttle body.

Does anyone know how to adjust the minimum air rate without a GM Tech 1 tool? Im assuming I can use a simple volt meter.

Thank you in advance.

You didn't hear it from me because adjusting the throttle body butterfly is like blasphemy around here but here you go,,,,

https://www.fiero.nl/forum/A...219-2-080905.html#p5

https://www.fiero.nl/forum/A...907-2-091410.html#p3

EGR like to leak, you checked that too, right?

Check your MAT sensor and engine temp sensor. Good fuel pressure and filter?

Bad negative (-) grounds, bad positive (+) cables including the main power terminal junction will cause all sorts of fits for the ECM causing a game of "chase the tail". On all my Fieros that I have owned, this is the first place I start.

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jetman
Silver 86 SE 2M6 4-speed, with "check wallet light"
Now fortified with 8 essential slices of bacon goodness

haha, I know people freak out when you say you wanna adjust the TB but the owner of the car was a service manager for a Pontiac dealer from 85-2004 and has owned several Fieros of various years/engines. He's the one who told me that they used to have to make this adjustment, at times when new during the pre delivery inspection!

Thank you for the link...much appreciated. He and I are going to go through the procedure tomorrow.

idle stop reset...
See my Cave, Idle Stop or get service manual http://www.fieronews.net/fusion/downloads.php

reset likely won't help.
check battery cables, engine grounds, and alternator. Bad power can cause idle hunting.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

[This message has been edited by theogre (edited 10-07-2012).]

I'd start with cleaning the egr. Make sure it seats. The V6 hates any egr flow at idle.

Just went through this with mine. Turned out to be faulty ICM, leaking EGR base gasket, and timing WAY out of spec.

I appreciate all of your suggestions...together we'll figure this out! We just went through the EGR system...Delco valve, tube and the gaskets. Set the timing when I replaced the ICM and pick up. But I will double check all...knowing me, prob a good idea. The idle was hunting prior to replacing those items but we didn't replace that stuff because of the idle.

quote Originally posted by jetman: Bad negative (-) grounds, bad positive (+) cables including the main power terminal junction will cause all sorts of fits for the ECM causing a game of "chase the tail". On all my Fieros that I have owned, this is the first place I start.

Where is the main power terminal junction you are talking about?