924Board.org

[Slam]

77.5 924. All emissions removed. Timing's on, plugs, etc. are good. No cold or hot start problems (I know, hard to believe...). Car likes to idle near 2000 RPM, and started this little trick after a new AAV was put in. I don't wnat to mess with the mixture until I've done as much else as I can. Idle bypass on TB is fully closed. I'm thinking vac leak somewhere but the intake tract boots are in good shape. Could this be injector seals?

Oh yeah - it's automatic. And it's white...
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'88 944 Auto - may or may not resurrect

[Ozzie]

I'd check that aav.
When hot its supposed to be closed.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Paul]

Has someone played with the throttle stop screw?
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[Slam]

Thanks guys - will check both. Didn't suspect the AAV was the culprit 'cause it's new. Throttle stop is so obvious I missed it completely.
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'88 944 Auto - may or may not resurrect

[968rz]

also check for small cracks in the hose from the AAV to intake
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Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

[geddes66]

Don't forget, the AAV, (If that is the air bypass valve to give it a fast idle when cold) is adjustable. I messed with a couple from the junkyard before getting it right. It must be removed to be worked, the Chiltons manual has instructions I think.
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The Porsche is now my son's, my car is cooler, slower but cooler.

[Slam]

Okay - AAV connector was one culprit. Clamped AAV line while engine was warm and idle dropped, so started there. Replaced the connector and that seemed to help. AAV works - checked that, too. However, after a run the car pulled its 2000 RPM idle trick again. Checked ground at connector - good. I know the AAV draws power from the fuel pump relay, so I'll have to trace that back to see if it's getting power properly. Throttle stop was fine. Got a question that may be related: When the distributor starts to fail (or the ballast resistors) will the tach needle float high and then return to proper reading? The car now cuts under hard acceleration - it's like fuel or spark are being cut off. I found a couple of loose wires to and from the resistors and a ground or two that needed fixing, so I did that. Didn't get it. Strange thing is, after I did this work the car ran fine all afternoon. This evening, it started acting up - after we'd bought gas from the local service station. Maybe we got bad gas?

Any tips?


-Update-

Car runs very well cold - just took it for a blast and it was fine. So if the AAV is the only variable apart from mixture, my guess is that the car warmed up, the AAV closed and the mixture ended up being too rich, killing the motor at WOT. Further guess is that PO adjusted mixture to compensate for AAV connector being ^#$%ed. Am I on the right track?
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'88 944 Auto - may or may not resurrect

[Mike924]

AAV shouldn't affect mixture greatly...

Are you sure you're not confusing it with the WUR?
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[augidog]

Check your timing
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1978 924 95 mile daily driver.
Audi TB/POR174M/High Flow Cat/2.25" exhaust
I knew that positive thinking thing wouldn't work.

[Slam]

Yes, augidog, I tweaked the timing. There's another thread near here all about that adventure. I finally got it. Thanks.
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'88 944 Auto - may or may not resurrect