924Board.org

[edh]

Hi

I'm in the UK, new to the BB - just looking at buying my first 931 - an '81 Series 2

Everything about the car looks fine, until you hit 4000rpm - there's a huge hesitation/misfire.

The car's at a classic dealer - they race Jags & Mustangs among others, so don't know much about 924's. They have had it on the rolling road, & apparently it's dumping huge amounts of fuel into the system at high revs

They are getting the AFM & injectors tested now

I've read a few comments here about the fuelling systems being a pain to fix

I'd appreciate any suggestions anyone has
- or is this car best avoided?

thanks

Ed

[Smoothie]

If when the hesitation hits, it's so severe that it feels like the car wants to throw you through the windsheild, then I'd suspect either or both the wastegate diaphragm is torn or the overboost cutoff switch is faulty and activating too soon. -Though this wouldn't account for a rich mixture.

If the hesitation is less severe, check the lower pressure pipe to turbo connection. It should be bolted via a small bracket to the front of the block. It's common for that bracket to wear through and cut the bolt over time. This leaves you with a loose connection, then as boost builds, it pushes the connection apart allowing some air to escape which also results in an extra rich air:fuel mixture, hesitation, misfire and you should also hear the air escaping.
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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

[cooper931]

[edh]

thanks for the suggestions - I'll ask them to check out the turbo pipe on Monday

Ed

[Smoothie]

The 2 that I mentioned were problems I actually had with my own car. Others with similar symptoms found their problems to be with the wur (need a cis tester to check), and someone else found it was a loose ground wire near the frequency valve (if I'm remembering correctly).
Good luck.
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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

[john h]

[edh]

still no luck

- they are having another go on a rolling road tomorrow, let's hope they find something

[Lizard]

I am pretty sure smoothie hit this 1 before, but the piece that slides over the top of the turbo compressor housing, and the charge tube bolts onto, yest the small 1, there is a 13mm nut that fits in here, and bolts this peice to the engine, make sure this is in, also make sure that the rubber ring on the exit for the turbo compressor housing is intact and in good condition.
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3 928s,

[edh]

well they still can't fix it

and won't sell it to me unfixed

- so I guess I'll have to look for another one

[numbbers]

edh, I think John Brown is on to the problem. I had a similar problem, and it turned out to be one of the rubber elbows on the vacuum pipe had split on the bottom where it could not be seen. It was fine at idle, but under boost the split would open up, dumping air to the atmosphere, and the CIS would put in more fuel to compensate for the increased air flow. The engine would go very rich, and miss like hell, and black smoke/carbon would blow out the tail pipe. It took me a couple of weeks to find the problem. You should offer the seller a lowball price to take the car as-is. Then replace the elbows yourself.
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1980 924 Turbo

[edh]

I've asked him if he wants to sell as is - he's not too keen at the moment.

I'll keep trying though

[wdb]

I think numbers has it right , so remember not to take any of your cars to that place for repair . if they cant diagnose and fix a vacuum leak , they dont have much experience as mechanics .