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| Can I manually manipulate my idle speed? (Page 2/10) |
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Vintage-Nut
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APR 15, 06:24 PM
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| quote | | I got a small, flat piece of wood + 1 folded shop towel, then sealed off the throttle body opening and the engine died immediately. So, as said above, that confirms I don’t have any vacuum leaks, correct? |
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I read a different test than sealing the throttle body but I never tried it....
| quote | Check for vacuum leaks by covering the IAC inlet passage inside the bore of the throttle body with your finger
If the engine continues to run at ANY RPM, you do indeed have a vacuum leak |
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I verified my vacuum system by disconnecting each line by capping/sealing one end; attached a hand operated vacuum pump with a gauge on the other end; pulled-out the atmospheric pressure to 20 inch-Hg and hold the pressure for 5 minutes. If the pressure didn't rise, the line didn't have any leaks...[This message has been edited by Vintage-Nut (edited 04-15-2025).]
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olejoedad
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APR 15, 07:10 PM
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Question for Kit....
On the throttle body, beside the throttle linkage cam there should be a very small (1/4") plug that covers a setscrew.
The setscrew was used at the factory to set idle speed and then plugged.
If the plug is missing, chances are someone has been messing with the setscrew.
I do not recommend messing with the setscrew unless every other cause for high idle has been eliminated.
(Edited to correct improper information.)[This message has been edited by olejoedad (edited 04-16-2025).]
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richard in nc
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APR 15, 08:17 PM
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mines a 2.5 which is different but mine had a problem where it idled at 2600 rpm.id go five miles away to eat and the idle stayed at 2600 til i got there.when i left the idle would drop down to almost normal.i changed the idle air solinold and its idled at around 1100 since.
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Kitskaboodle
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APR 15, 08:45 PM
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Thanks again for all the additional input.
As Vintage-Nut mentioned above, it’s a good idea to check or replace the coolant sensor as top priority. I haven’t tested it yet but since they’re relatively cheap, I went ahead and ordered one from Amazon. I’ll update you all later on this.
OldJoeDad: I have never touched that plug on top of the plenum. Ironically, the plenum I have in the car was from a member in Oregon who used to do a plenum / manifold powder coating service. His name is “Electrathon”. I had to double check it and the powder coated replacement I got from him is indeed capped. Kit[This message has been edited by Kitskaboodle (edited 04-15-2025).]
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Patrick
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APR 15, 11:45 PM
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| quote | Originally posted by Kitskaboodle:
OldJoeDad: I have never touched that plug on top of the plenum. Ironically, the plenum I have in the car was from a member in Oregon who used to do a plenum / manifold powder coating service. His name is “Electrathon”. I had to double check it and the powder coated replacement I got from him is indeed capped.
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You have a powder-coated throttle body?  That's where the set screw is located that has a cap over it from the factory.
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olejoedad
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APR 16, 02:35 PM
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| quote | Originally posted by Patrick:
You have a powder-coated throttle body? That's where the set screw is located that has a cap over it from the factory.
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You're correct, Patrick. The plugged off idle adjustment screw is on the throttle body, not the upper plenum.
My bad. Thank you for pointing out my error.
I have edited my post to reflect the proper information.
I seldom look at the stock Fiero engines, I see more swapped engines.
I figured the adjustment screw was worth a mention, however, as no one else had brought it up in the conversation.
I'm surprised no one else thought to bring it up as a possibility.
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Patrick
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APR 16, 03:09 PM
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| quote | Originally posted by olejoedad:
I figured the adjustment screw was worth a mention, however, as no one else had brought it up in the conversation.
I'm surprised no one else thought to bring it up as a possibility.
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To be honest, it seems like such an obvious thing to check, and it has been mentioned a thousand times previously in these forums (and everybody checks the old threads, right?  )... that I guess it's easy to overlook mentioning it yet again. But yes, it was definitely worthwhile for you to bring up in case Kit was unaware of this possible cause of a high idle speed.
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Vintage-Nut
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APR 16, 03:18 PM
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| quote | I figured the adjustment screw was worth a mention, however, as no one else had brought it up in the conversation.
I'm surprised no one else thought to bring it up as a possibility. |
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Because to me, it is the last thing to do....
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olejoedad
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APR 16, 05:05 PM
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| quote | Originally posted by olejoedad:
If the plug is missing, chances are someone has been messing with the setscrew.
I do not recommend messing with the setscrew unless every other cause for high idle has been eliminated.
(Edited to correct improper information.)
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Which is why I stated the above.
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Kitskaboodle
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APR 16, 07:18 PM
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Oops…I stand corrected again. 🙁 (I told you guys I’m getting old - or as George Burns once said, “you’re only as old as the girls you feel” 😀)
Yes, the throttle body is not powder coated! 😀
Anyways, here’s a pic to show you my engine. You can barely make it out but if you look hard you can see that the plug is there on the throttle body. Kit
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