924Board.org

Retaco_04 · Joined: 27 Jul 2005 Posts: 2

Hi I hope somebody might be able to help, I have a 1981 924 Turbo Euro Model. There have been a few problems since I bought her.
The head gasket blew which later on investigation showed that the head was knackered.
The car was put back together with a reconditioned head but everytime the car goes above 3000 - 3500 rpm in any gear it surges back and forward and it seems like the turbo is refusing to work. It feels like I am about to go through the windscreen of the car.
Sorry for the long post but any help in diagnosing would be appreciated
Chris

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

Does the car have a boost gauge ? It sounds to me like the wastegate isn't working and as you hit 3000 rpm ,where the turbo puts out it's max boost,the overboost switch is killing power to the fuel pump.
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1981 931, Sabine
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JamesWilson · Joined: 10 Jun 2005 Posts: 132 Location: San Diego, CA

This seems to be a fairly common problem, mine does the same thing. New wastegate line going in this week, and maybe a new wastegate (check eBay right now for "930 wastegate", a few should pop up), should fix that problem.

-JamesW
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'82 924 Turbo (not stock) - soon returning home?
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Smoothie · Posted: Thu Jul 28, 2005 4:09 am Post subject:

Yes, "like it's trying to throw you through the windshield" is exactly the feeling you get when the fuel pump cuts out during accelleration. Two possible causes are 1) hitting the rev limit (,but that's up around 6500rpm) and 2) the overboost limiting switch's been tripped due to the wastegate being stuck closed, its' diaphragm being torn and/or a leak in the wastegate control line. You can be about 100% sure #2's the cause in this case and the wastegate needs work.
I wouldn't just buy a used wastegate and throw it on. It really should get an internal look-over and pretty much count on it needing a new diaphragm, plus the valve may need work as well. Diaphragms generally last about 5 years - though I'm getting some extended life from my current one (I have the black rubber one and treated the vent side of it with a silicone preservative before it was installed).

[Actually, #1 wouldn't even apply to a Euro 931 the same as to a US 931 because you should have rev-limiting built into the distributor rotor, so in your case, spark would be interrupted on over-rev. US 931s got a rev-limiting fuel pump relay that cuts power to the fuel pumps on over-rev.]
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"..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

Paul · Posted: Thu Jul 28, 2005 9:21 am Post subject:

Overboost problem at 3000 rpms? I doubt it.

Make sure the lower pressure duct that connects to the output of the turbo is sealed correctly and that is bolted to the block.
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White 87 924S "Ghost"
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Owned and repaired 924s since 1977
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