Rennlist - Porsche Discussion Forums - Symptom high rev ( 3000 rpm) at cold start!

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7930	01-23-2018 08:30 PM

Symptom high rev ( 3000 rpm) at cold start!

I've noticed my car revs high for about 15 seconds or so at cold starts. I was told it's my aav. It's been recommended,instead of tinkering with the aav, attach a reducer of some sort in the hose entering it. Is there anyone here have experienced this before? Looking forward to your comments and advice.

Mark Houghton

01-23-2018 10:49 PM

A quick diagnostic is to use a large pair of needle nose pliers, or something similar, to pinch the hose shut on a cold start. If your idle drops to almost stalling, then yes your valve may be suspect. It can be adjusted, but would require taking it apart and driving a brass pin out to close the window within the valve, letting less air in. You'll see that brass pin on the exterior of the housing. Sorry I can't be more descriptive. I had the opposite symptom and wished for a higher rpm when stone cold starting, and driving said pin in opens the window a bit. The reverse would be true for you, but you would have to drive the pin out from the inside of the housing. Experiment with a smaller diameter hose wedged inside the existing hose, probably well less than half the ID of the stock hose.

Has this always been an issue, or just a recent development?

7930	01-24-2018 03:28 AM

When I purchased it from my brother it already had the issue,but I forgot all about it until just recently after the motor got rebuilt. My mechanic told me it's the aav. I just took his word for it since he works on Porsche motors a lot. He told me to either take the aav apart and adjust or even an easier way just put a reducer in the hose that is entering it. Play with different sizes of reducers until the proper revs is achieved. I will go ahead and do the pinch test with the pliers and confirm it is the aav before deciding which way I will go. Thanks

7930	01-25-2018 01:13 AM

Did the pinch test with a needle nose vice grip, it is definitely the aav.

7930	01-25-2018 01:42 AM

I think I've been calling the part wrong, it's the aar that is the issue not the aav.

Mark Houghton

01-25-2018 08:57 AM

Quote:

Originally Posted by 7930 (Post 14753749)

I think I've been calling the part wrong, it's the aar that is the issue not the aav.

Correct, a common mistake.....but we knew what you were talking about anyway. It's a regulator, not a valve. A valve is on-off, whereas a regulator provides infinite adjustment. You should be able to see the T shaped window inside on the rotating disc and should be able to move the disc (just stick a pencil in there and see if you can get it to move), Might be stuck wide open. Lubricate and/or take the whole thing apart. Very basic operation, not rocket science.

7930	01-26-2018 01:36 AM

Thanks for the info Mark! I haven't removed the part yet, but removed the hose. I saw the disc and stuck a small screwdriver and was able to move it. I could feel the tension.

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