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smart931 · Posted: Mon May 03, 2010 3:14 pm Post subject: Hard starting 931

So, i managed to get my 931 running and better still, i got it through smog. It's running great now. I've been driving it all over the Big Sur coastline. Great fun.
I do have one issue though. It is a bugger to start first thing in the morning. When it's cold it'll churn and churn and do nothing. I prime the pump and mash my foot on the gas and it'll finally splutter into life. If i then turn it off straight away it'll fire up instantly, and do that all day.
The electrics on this car are a black art to me.
I'm guessing it's something to do with the cold start mechanism but i don't understand how it really works. The last mechanic that worked on my car took my Haynes manual and didn't return so i'm totally in the dark.
Any tips on testing the cold start on an 82 931 US model?

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1982 Porsche 931 (Sold)
2000 Smart Fortwo (Waiting for import)
1972 Opel manta (Left in England)
1965 Chevrolet Corvair (Left in England)
2010 Mazda 3 (Ex got this in divorce)
1974 Triumph TR6 (sadly gone)
1968 Ford F250 Camper Special (Daily)

Joes924Racer · Posted: Mon May 03, 2010 5:00 pm Post subject:

Good luck bro wish i could help you.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

Smoothie · Posted: Mon May 03, 2010 11:31 pm Post subject:

The owners manual says to press and hold the throttle to the floor to start when starting's difficult. This definitely helps if there's a hot start problem, and also aids cold-starting. In fact it will start the car even with a non-functional cold-start valve. I tried this a few months back - with engine cold after sitting unused overnight, I disconnected the CSVs' electrical connector, pressed the throttle to the floor, and started it. It started right up within a few cranks.
The CSV operates for a max of roughly 10 seconds when the engine's cold (as determined by the TTS (thermo-time switch)), only while the starter is activated.
Try this for your next first cold start of the day: Disconnect the elect. connector from the CSV and go through your usual morning cold start saga. If things go the same as usual, the fact that nothing's changed with CSV disconnected can be taken as a hint that there's a CSV problem. -And until it's fixed: Before starting, press and hold the throttle to the floor, then start it.
The "for sure" test of the CSV involves disconnecting and removing it, re-attaching the fuel line and elect. connector, placing it in a glass jar, turning the ignition switch to start, and observing the fuel spray (and pattern (fine conical spray)) from the CSV. As mentioned, it should only spray while the ignition is switched to "start" and for a max of ~10 seconds.
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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

Nobbi · Joined: 24 Aug 2006 Posts: 1398 Location: Germany

well, could be the fuel accumulator that doesnt hold the pressure during the night? That would explain why it starts for the second time right away.

Quick shot in the dark....

Nobbi

_________________
NA 924 - april/1977- 4-speed-audi gearbox.
500.000 km with fun.....and new toy:Porsche 944 S2 Cabriolet.Other car Daimler c-class cabby,brandnew..Plus : DEUTZ 4005 tractor Built 1967

Piper · Joined: 11 Feb 2010 Posts: 24 Location: Falkirk, Scotland

smart931 · Posted: Tue May 04, 2010 3:19 pm Post subject:

Thanks for the input guys. Ill have a look at it at the week end. It is working well enough to drive to and from work. It started right up after work today. The weather was warm, so i think it must be the cold start valve.
How tricky is it to replace? Without a manual.

_________________
1982 Porsche 931 (Sold)
2000 Smart Fortwo (Waiting for import)
1972 Opel manta (Left in England)
1965 Chevrolet Corvair (Left in England)
2010 Mazda 3 (Ex got this in divorce)
1974 Triumph TR6 (sadly gone)
1968 Ford F250 Camper Special (Daily)

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Just remember, there are three things involved that you will need to check:
1. The CSV itself
2. The TTS (thermo time switch)
3. All of the wiring between the CSV & TTS

Don't just assume if the CSV doesn't squirt fuel that it's bad...it could be one or BOTH of the other items. Also, don't assume that if one of the tests fail that the other two items are OK. So be thorough, and check all three.

It would be helpful to get another Haynes, although you need to be aware that it doesn't cover everything re: the 931. Some of the 931-specific stuff is covered in the supplement (Chapter 13), but not all. However, the CSV/TTS operation, location, and testing should be universal to all of the 1980-onward cars.

The CSV is located on the side of the intake manifold facing the windshield.

The TTS inserts into the rear water flange on the back side of the head and is a real PITA to get to.
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erstwhile owner of just about every 924 variant ever made