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xanderdeg
Joined: 08 Jul 2012
Posts: 286
Location: Vancouver, BC, Canada
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 Posted: Tue Nov 05, 2013 9:24 am Post subject: High idle after startup |
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After starting my engine warm, it's idling at around 1500rpm. After driving for a bit it idles just below 900rpm and it's a little shaky sometimes.
Not sure what is causing this, maybe my AAV is stuck? |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Tue Nov 05, 2013 9:26 am Post subject: |
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The idle bypass system is based on temperature and isn't the fastest to respond after power is applied.
Worth a shot to clean it out and give it a good test.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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larchie
Joined: 19 Jun 2003
Posts: 297
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| Posted: Tue Nov 05, 2013 12:18 pm Post subject: |
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| Did the high idle when warm just suddenly occur or was there work done prior to the issue? Lots of possible factors but it might be worth checking first for vacuum leaks, auxiliary air valve operation or leaks, and the auxiliary air regulator and its supply voltage. |
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!tom
Joined: 28 Aug 2006
Posts: 1941
Location: Victoria, BC Canada
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| Posted: Tue Nov 05, 2013 12:40 pm Post subject: Re: High idle after startup |
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| xanderdeg wrote: | | Not sure what is causing this, maybe my AAV is stuck? |
I'd expect a stuck AAV would give the opposite symptoms.
Could be a bad WUR; it's tuned to be rich enough so that it starts, and when it's warm, it's overly rich causing the drop in RPM.
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78 924 NA
5-lug |
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xanderdeg
Joined: 08 Jul 2012
Posts: 286
Location: Vancouver, BC, Canada
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| Posted: Tue Nov 05, 2013 1:43 pm Post subject: |
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What's a WUR?
And I'm not sure if that would cause such high idle after warm starts but that's only my uneducated guess...
| Quote: | | Did the high idle when warm just suddenly occur or was there work done prior to the issue? Lots of possible factors but it might be worth checking first for vacuum leaks, auxiliary air valve operation or leaks, and the auxiliary air regulator and its supply voltage. |
It was doing it a little before but nothing as high as it does now.
I've checked for vacuum leaks and there don't seem to be any. Will check again as well as the AAV and AAR. Thanks. |
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larchie
Joined: 19 Jun 2003
Posts: 297
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| Posted: Tue Nov 05, 2013 1:51 pm Post subject: |
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!tom wrote | Quote: | | I'd expect a stuck AAV would give the opposite symptoms. |
I could be wrong but my understanding is that when the engine is warm the normally operating auxiliary air valve is closed. If not, it should be cleaned, fixed, or replaced. On the other hand, if the idle is high and clamping a hose to the auxiliary air valve causes the idle to drop, then the auxiliary air valve is open and thus defective. So if the valve doesn't close all the way when warmer, then the idle would be higher than normal. On many cars, there's a small nut on the side that can be loosened and then moved to adjust the valve and increase or decrease the idle speed.
xanderdeg wrote | Quote: | | After driving for a bit it idles just below 900rpm and it's a little shaky sometimes. |
So if I am mistaken in my understanding (as I often am!), and as !tom expects the idle to decrease, I think it's still worthwhile to check the auxiliary air value as cracked hose or dirty valve can result in an irregular idle on these cars.
Certainly the warm-up regulator could be a factor, but I understood xanderdeg to say the idle was high after starting when the car was warmed up. Only later, after driving some, the idle dropped. |
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