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| high idle when cold (Page 1/2) |
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katie80
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OCT 26, 01:13 AM
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I have an 84 2.5L and ever since I got it, it idles wayyyy too high. it's only when it's cold out (the colder, the higher. the coldest I've started it is around 30 degrees and it shoots up to 3k rpm.) when it's warm out, it starts and idles at like 1500 or 2000 which is still a little higher than I would expect, but not as bad as 3000 at 30 degrees right on start up. it comes down after the engine warms up.
any ideas?
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Forrest
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OCT 26, 09:51 AM
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Are you sure there are no vacuum leaks?
EGR tube at the base of the intake was my issue.
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theogre
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OCT 26, 01:59 PM
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Maybe Nothing is Wrong.
Engine warm to hot idle should be ~ 800-900 RPM depending on trans w/ it.
Cold to very cold then 2000 - 3000 is common when started and soon after gets slower and slower til reaches normal idle.
Is to keep engine running when Trans goes into Any Gear.
ECM uses ECT to set Cold Idle even when IAC is reset after driving > 35 MPH after discon the battery etc.
Use ECM scan tool to see ECT and other sensors output.
If ECT says colder then weather low the last several hours then sensor or wires to it could have problems making engine w/ even higher idle then should.------------------
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
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katie80
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OCT 27, 05:33 PM
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| quote | Originally posted by theogre:
Maybe Nothing is Wrong.
Engine warm to hot idle should be ~ 800-900 RPM depending on trans w/ it.
Cold to very cold then 2000 - 3000 is common when started and soon after gets slower and slower til reaches normal idle.
Is to keep engine running when Trans goes into Any Gear.
ECM uses ECT to set Cold Idle even when IAC is reset after driving > 35 MPH after discon the battery etc.
Use ECM scan tool to see ECT and other sensors output.
If ECT says colder then weather low the last several hours then sensor or wires to it could have problems making engine w/ even higher idle then should.
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I was only asking since this is the first car I've had that's done this. but if it's normal for a fiero then it's fine. just seems strange to me.
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buddycraigg
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OCT 27, 07:36 PM
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Brian D
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OCT 31, 09:54 PM
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It's been a long time since I had a 4cyl but i remember having the same issue with high idle. Did you check the IAC valve? I'm pretty sure replacing it fixed my issue.
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Patrick
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NOV 01, 01:03 AM
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| quote | Originally posted by katie80:
84 2.5L... it idles wayyyy too high. it's only when it's cold out (the colder, the higher. the coldest I've started it is around 30 degrees and it shoots up to 3k rpm.)
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My first Fiero, an '87 duke, had the same issue. I did not want a cold engine racing all the way up to 3000 RPM before the engine oil even had a chance to circulate. It was also noisy as hell, and I didn't want the neighbors thinking I was revving the engine like an idiot on purpose!  So I went through the trouble of installing a switch (mounted in the cab) which would cut the power going to the IAC stepper motor. I would turn the switch OFF before I turned off the warmed up engine, and left it OFF when I started the cold engine the next day. This would prevent the IAC valve from opening. Once the engine warmed up a bit in a minute or so, I would then turn the switch ON so that the IAC would function normally. This mod actually worked rather well, as long as I remembered to turn the switch OFF before I turned off the warmed up engine. It never set any codes either.
Having said all that, my '84 duke doesn't have the cold excessively high idle problem. Go figure.  [This message has been edited by Patrick (edited 11-01-2021).]
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RotrexFiero
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NOV 01, 08:17 AM
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We are so use to the more modern engines, engines of today that have better sensors and programming, that can regulate an engine under all conditions. Computers on engines were a new thing back then.
We forget that old days, and how you use to let an engine warm for a while before driving.
Today, you get in it, start it up, and go!! Anything less it's a problem.
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buddycraigg
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NOV 02, 09:59 PM
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I thought you guys were crazy, but too many of you have mentioned this.
I have never seen that happen.
I don't have an answer to fix it, cause I've never had to fight with it.[This message has been edited by buddycraigg (edited 11-02-2021).]
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Williamm65
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DEC 19, 09:43 AM
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| quote | Originally posted by Patrick:
My first Fiero, an '87 duke, had the same issue. I did not want a cold engine racing all the way up to 3000 RPM before the engine oil even had a chance to circulate. It was also noisy as hell, and I didn't want the neighbors thinking I was revving the engine like an idiot on purpose! So I went through the trouble of installing a switch (mounted in the cab) which would cut the power going to the IAC stepper motor. I would turn the switch OFF before I turned off the warmed up engine, and left it OFF when I started the cold engine the next day. This would prevent the IAC valve from opening. Once the engine warmed up a bit in a minute or so, I would then turn the switch ON so that the IAC would function normally. This mod actually worked rather well, as long as I remembered to turn the switch OFF before I turned off the warmed up engine. It never set any codes either.
Having said all that, my '84 duke doesn't have the cold excessively high idle problem. Go figure.
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Witch wire do you cut into
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