924Board.org

Meneer aard · Joined: 27 Jan 2006 Posts: 73 Location: Netherlands

When i drive my car, and stops or shifting the engine makes arround 1500 rpm.

When i start (cold start) de engine speed is 900-1100 rpm. I think the throttle cable is not function well?

Or maybe is the problem somewhere else?

Ozzie · Posted: Mon Jan 30, 2006 7:38 pm Post subject:

Most engines when hot should idle approx 900 rpm.
This will be different when cold, how different depends on the state of the WUR and AAV.
I would say someone has adjusted your cold idle to cover problems with these two items.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Meneer aard · Joined: 27 Jan 2006 Posts: 73 Location: Netherlands

Ozzie · Posted: Mon Jan 30, 2006 10:22 pm Post subject:

When cold:
The air valve opens when cold to allow more air to lift the air sensor and increase the idle speed temporarily.
The WUR reduces the pressure holding the air sensor down allowing it to lift further and rich the mixture.
When hot the air valve and WUR should not affect the idle. This is why all adjustments for the idle and air/fuel mix should be done when hot.

People compensate by adjusting the cold idle when the problem is the WUR or AAV.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Smoothie · Posted: Tue Jan 31, 2006 4:13 am Post subject:

924NA? 19??
Put the model and year in your signature.

_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Meneer aard · Joined: 27 Jan 2006 Posts: 73 Location: Netherlands

924er · Posted: Tue Jan 31, 2006 9:57 am Post subject:

true that ozzie ur right about that. when my car is cold in the morning it starts up quick but idles very low until the car gets warm then idles at 900rpm.

Q: hey how come when i turn the ignition off on my car it shuts off, then shakes and sounds pretty ugly then white smoke comes out my intake, i checked the FAQ no answers. usually i found a way to do it, is to turn the key slowly when shutting it off, then it wont shake.

thanks alot, this problem is really bothering me
_________________
80' Porsche 924 NA - Slower then a S L O W
86' Porsche 951- New toy

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

Sounds like dieseling. Sometimes, IIRC, it makes the engine run backwards, pushing fumes out into the intake. Bad for the engine internals. Usually caused by hot spots of carbon in the combustion chamber and a leaky fuel injector. Someone correct me if I'm wrong. (I'm only going off what I recall about a crappy chevy engine I once had that would do the same thing.)
_________________
'80 924 n/a SOLD

924er · Posted: Tue Jan 31, 2006 12:18 pm Post subject:

yep, i think ur right. i did some google search:

http://en.wikipedia.org/wiki/Dieseling

anybody else have any idea????
_________________
80' Porsche 924 NA - Slower then a S L O W
86' Porsche 951- New toy

Ozzie · Posted: Tue Jan 31, 2006 1:54 pm Post subject:

I think I mentioned in your other post that it was probably running a bit rich.
Adjust the fuel air mix to correct value and put in fuel injector cleaner and run on premium 98 ron unleaded.
This will hopefully then clean out the carbon buildup.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK