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Aussie931 · Joined: 28 Aug 2006 Posts: 55 Location: Canberra

Does anyone know if the vacuum limiting valve on the vacuum line harness or the check valve hanging off the end of one of the vacuum hoses is a.k.a the deceleration valve? I am trying to isolate the decel valve but am unsure exactly which one it is.
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1979 Series 1 924 turbo

Smoothie · Posted: Wed Oct 11, 2006 1:12 am Post subject:

The vacuum limiting valve is aka the decelleration valve. In this pic <click>, it's located 1/3 from the bottom and 1/3 from the left - a disk shaped part mounted standing on edge (just below the "T" in that metal pipe). I'm about 99% sure all 931's got the same one. I know the 924na version is different. Once you've found it don't lose it - they're expensive little buggers.

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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

Aussie931 · Joined: 28 Aug 2006 Posts: 55 Location: Canberra

Thanks!
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1979 Series 1 924 turbo

Tigger937 · Posted: Wed Oct 11, 2006 2:29 pm Post subject:

Smoothie · Posted: Thu Oct 12, 2006 1:07 am Post subject:

Tigger937 - Are you sure it's the decel valve that's causing the high idle? Series 2 have the intake air temp sensor.. I found my high idle (especially when very cold) was related to that air temp sensor circuit. Next time you find it wailing away, try unplugging the sensor to see if that doesn't drop the idle. If it does, you can install a momentary switch to "reset" it from the drivers seat. I have instructions for it somewhere here, so let us know...
As far as repairing the decel valve - I don't know, but my guess is no.
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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

Tigger937 · Posted: Thu Oct 12, 2006 2:32 pm Post subject:

Smoothie · Posted: Thu Oct 12, 2006 3:12 pm Post subject:

It's not the air temp sensor going bad that causes the high idle.. It seems to be low temperature, DITC's processing of the low temp reading and possibly also the influence of an incorrect idle speed setting (which affects idle timing on DITC cars). I had it happening regularly about 2 years ago, wired up my momentary switch as a "quick" fix, then the following year (after more fiddling with the idle speed), I don't think I had to use the switch once. -So I'm thinking the high idle may actually be a symptom of incorrect idle speed (and some crappei decision making on the part of the DITC box).

(DITC = "device intended to confuse" (aka- "digital ignition timing control") on 931 series 2 cars)

btw- silicone very bad for o2 sensors and if I'm remembering correctly, cat converters also.
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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

Tigger937 · Posted: Sat Oct 14, 2006 11:49 am Post subject: