I just got my engine back in and finished hooking everything up today and started her up. She would run fairly well with some throttle but wouldn't idle. Timing was able to be set by propping the accelerator to keep the engine running ~1,500 rpm (yes, in diag mode) and is right on at 10 btdc.

Stepping back to the work that was done, I noticed that the set screw on the throttle body was visible telling me that someone has messed with it before (it's originally blocked off right?) and that the ECM had been opened. I replaced the ECM with a stock unit from a forum member and have installed a new timing chain, injector o-rings and assorted gaskets from the intake manifold up. I pulled the IAC and cleaned it well (was very dirty) and the ports in the throttle body. I also had to replace a cracked manifold so both are now missing the extra blockage where 3&5 and 4&6 meet the main tube.

In order to get her to idle on her own I had to turn the throttle body adjustment screw in about 1 1/2 turns and she would sit at about 500 rpm. I turned it in until she was bobbing between 800 and 1000. The good thing is I took her out for a quick test run and "accidentally" left a few feet of rubber without really stomping her so she has much more power than before I did the work. The bad, she's obviously running lean at idle (popping on deceleration).

Here's my question: how do you set the throttle body set screw? I can't find anything searching the forum of in my Chilton manual. Is there a standard number of turns out from bottom? I rebuild old 70s Honda 4-cylinder motorcycles and am used to playing with carbs but this is a bit different...

Thanks
James

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It is the mark of an educated mind to be able to entertain a idea without accepting it.
Aristotle

There are a couple post on doing it.
As I recall you jump AB with a clip.
Turn the key on and the IAC motor should run the pintle all the way shut. (be sure your iac is working and clean)
Unplug the iac motor so it will stay shut.
Start the car and keep it running.
Adjust the throttle screw so that the engine will idle at 500 or close to it.
Put everything back to normal and plug the iac back in.
If your iac and ecm is working you should idle at 900. If not then something is not working in the idle curcuit and will to be addressed.

Here is a link. Look about 1/4 way down.
https://www.fiero.nl/forum/A...090219-2-080905.html

[This message has been edited by Dodgerunner (edited 09-18-2010).]

quote Originally posted by Dodgerunner: There are a couple post on doing it. As I recall you jump AB with a clip. Turn the key on and the IAC motor should run the pintle all the way shut. (be sure your iac is working and clean) Unplug the iac motor so it will stay shut. Start the car and keep it running. Adjust the throttle screw so that the engine will idle at 500 or close to it. Put everything back to normal and plug the iac back in. If your iac and ecm is working you should idle at 900. If not then something is not working in the idle curcuit and will to be addressed. Here is a link. Look about 1/4 way down. https://www.fiero.nl/forum/A...090219-2-080905.html

Thanks Dodgerunner. I searched with every variation of throttle body setting, screw, adjustment, etc and couldn't find it. I really appreciate it.

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It is the mark of an educated mind to be able to entertain a idea without accepting it.
Aristotle

See cave. idle stop
has all three engines

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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...)

The timing might be wrong because you adjusted at high idle. If you move the tb set screw the TPS values will also change, in your case it might be just off-idle right now that's why the extra power in take off.
-Let the engine get fully warm.
-Back the set screw a little at a time. Allow about 10 sec. for the ecm to compensate.
-Keep repeating this until you get the recomended idle speed.
-Chech you TPS volts and adjust it, should be 0.54 volts at idle.
-Desconnect the battery, wait 10 sec. and go for a drive past 45mph.

See if that helps.

You should have about 35-40 IAC counts at warm idle in neutral. To get the number of IAC counts you'll need a scanner or an ALDL cable.

Make sure your TPS is in the vicinity of .5v also.