How far open should AAV be?

[loot87]

I think I have a bad Aux Air Valve because of cold start issues. It's 90% closed at room temp (crecent moon with square notch). It doesn't seem to change when in the freezer. I haven't hooked it up to 12v yet.

How far open should it be at room temp? I have attached a pic.

Thanks.
Chris

[Scott R]

I just went down to my garage to check my spare, and it's about 65 deg currently my spare AAV is about 20% open. If I freeze it (from memory) it closes to all but say 2% open.

[vizail]

This Units are not Very presice . So be patiente and verify the opening and closing of it. If they stay open the Air Calibration is very hard. Get a New unit or if you have an extra unit verify the closing and opening

Vic

[Scott R]

I should also add that per another post here, I "upgraded" per say to the 17 ohm version from the 33 and it works much better.

[Paulporsche]

That is the AAR(egulator) not the AAV(alve). If you search " mystery train" or "mysterytrain" you will see how he got this thing to work better.

Have you tried your revised unit on the car?

[loot87]

You're right. Sorry about that. I see lots of people calling it the AAV but didn't realize there was another part called that. I can't find AAV in the PET. Is that what's also called the vacuum limiter?

[smestas]

I had a previous thread on the same topic. It might answer some of your questions.

Is This AAR Good or Bad?

[Paulporsche]

Simon,

Tell us about the nut and bolt you added to the AAR. You were able to adjust the sensitivity with them?

[loot87]

I think I know where the AAV confusion started: the diagram in the Bentley book calls it an AAV. Adrian also reprinted this diagram.

Anyhow, I came how today and noticed that my AAR was closed farther than before. Sitting on my desk in the sun and it reaching 70 degrees here (about 85 in my home office) made a noticeable difference. I put it in the freezer for an hour. It was open about half way. I then baked it at 350 for about 15 minutes. Closed all the way. So I guess that's not my problem.

Thanks for the replies. I guess it's time for a fuel pressure tester.

[Elombard]

Where are you at? you can borrow mine.

Yes Simon tell us how that works.

[Paulporsche]

What problems are you having? Also, I don't think I saw what year your car is. You may be experiencing the typical WUR related problem of too high cold control pressure.

[loot87]

I'm near Denver. Thanks for the offer, but I think my AAR is fine.
My problem is this:
1) when stone cold, starts OK but a little rough. Takes some throttle to bring the idle up.
2) when warm, starts fine.
3) when sitting for more than an hour but less than the time it takes to be stone cold, will just turn and turn without firing. Sometimes it takes more than 30 seconds of turning to get it to fire. I haven't killed the battery getting it started, but I'm afraid that I will someday.

I have a 91 Turbo. I'm posting here because there's more people here with CIS than the 964 group.

[Paulporsche]

1 could be the WUR/ccp. You should check the pressure. You may be able to simply knock the plug in to get it correct.

3 sounds like either the fuel accumulator or check valve. Lots of info on this via a search.

[loot87]

Do you know where to find the check valve on a 91 Turbo? I'm guessing it's somewhere in between the rear pump and accumulator but I haven't dug in to find the rear pump.

[WERK I]

I believe the check valve is located on the front fuel pump. Same as earlier 930's. The front fuel pump is located behind the front suspension pan. A real treat to get to.

[vizail]

loot

The Valve is part # 911 608 211 00 or valve # 893 906 093

Vic

[loot87]

Thanks. I found it in the PET after much looking. It calls it the "retaining valve".

[Mysterytrain]

Paul is correct you need to look at your pressures. Th AAR is Porsche's lame attempt at an automatic throttle device during warm up. The larger the opening when cold the faster the engine will idle. The important thing is that it closes completely and seals the opening once the car has warmed up. If the AAR is leaking then your idle will be high and then folks start to screw with the mixture and idle speed and things way out of whack.

[vizail]

Ok Gurus
If you have to turn your Air Mixture Screw in the Trottle Boby almost to the close position it might be indicative that one of your CIS componets is leaking( Vacum Leak) that is .

Vic

[vizail]

Hey Guys I was just cheking a spare AAR and apply some 12v for a few minutes and I just notice that after complitly closed, it still let some Vacum in.
Then I just took out others (AAR) that I have for spares and I noticed that some of them restrict more vacum that others. They supposed to close all the way and restrict or shot the Vacum ?Or are they defective?

Vic