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964 idle problem

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Hello to all, I've just bought a 964 C2, one owner from new and needs a good tidy up. When I drove it home all seemed fine until I had to stop at a roudabout where the car died, so I started it and launched off to the same problem everytime I stopped. I could keep it running by keeping the revs at 2k. The car has not been used much over the past 4 years and probably needs a good service. I intent to change the obvious things like dizzy caps & rotors, plugs, air filter etc:, but is there anything obvious I should be looking for ? Is this a common problem or am I the lucky first recipent of such a problem ?
Thanks
 
Peter,

The problem of stalling sounds very reminiscent of the effects of a lightweight flywheel. Do you know if it has had one fitted?? Other potential problem areas are contaminated idle control valve and/or air flow meter - often caused by overfilled oil. It might be worth posing the question on the 964 Yahoo Group here

Regards

Dave
 
Did you check the lambda sensor?
Did you check the idle control microswitch is engaged when you release the throttle?
 
Peter,

If the car has been standing around and the battery has gone flat or been disconnected at any time, this could be a cause. I was told when i fitted a new battery, to let the car idle for 15 to 20 mins so the ECU can reset itself. When i first started it up, the idle was all over the place but, sure enough, after about 10 mins up and down, it rectified itself. Maybe worth a try. Try the cheap options first!

Good luck
Martin
 
Thanks Martin, the car has been unused for about a year, with the battery disconnected, so I'll give it a go.

Dave, I've no idea if it's got a lightweight flywheel, how do I check ?

PhilRS, I've no idea what a lambda sensor is, where it is, or what it does, same goes for the idle control microswitch !

Sounds like I need a workshop manual, as I'm not really interested in giving some dealer a load of cash, yes it's a Porsche, but it's only a car ....... can't be that hard to sort out !
 
Hi Peter,

I've read of a workshop manual, but never seen one advertised and I understand it's very expensive. I suggest instead that you obtain a copy of a book by Adrian Streather call the "Enthusiasts Companion". It's widely advertised and will cost you £40-50 (but is well worth the money).

I've checked quickly the troubleshooting section and I can't see it addresses your specific problem. However, a copy of the book would help you understand what to do about the suggestions made so far.

A couple of other theories for you. When the the battery is disconnected, the Bosch Motronic engine management system (DME Control Unit) loses some of the programming it develops as a consequence of the car being driven. This should sort itself out after the car has been driven for 15-20mins. However, some control units (e.g. mine) seem unable to do this sometimes and therefore require manual assistance by a competent mechanic using a diagnostic tool (a Bosch 'hammer'). An alternative theory, and one you can easily try for yourself, is to replace the DME Relay (R41) in the fuse box (left rear of the fuel tank in the boot). These are fairly cheap and easily obtainable from any Porsche parts outlet. The correct part should have a 993 part number. Even if this doesn't solve the problem, it's well worthwhile carrying a spare with you in any event.

As a 964 owner of exactly one year's standing, my further advice would be to find a Porsche independent specialist near you whose work you are happy with (you can ask on the Forum for recommendations near you). They are fantastic cars, but they can go wrong and be a devil to sort out without the right tools / knowledge.

Hope this soon gets sorted for you.


 
Thanks for that, I'll keep a lookout for the book.

What does the DME relay actually do ? I've seen them on ebay for £20, so having one in 'stock' is easy,

Cheers
Peter
 
I've just found the book on Amazon for £44.60, sounds like it's well worth buying and as it's less than an hours labour there's no excuses .......
 
Peter,

I'm not a techie, but Adrian's book says it "provides power to the DME control unit, oxygen sensor heater and fuel pump".
 
Peter,

Good luck. Let us know how you get on. Be sure to let the car idle for that amount of time. I tried driving mine initially and found this did not cure the problem. It was a friend of mine who enlightened me after his car was suffering the same fault.

Martin
 
Thanks Elliot, I'll start investigating. I plan to change items like dizzy caps, rotor arm, plugs, etc: as I suspect they have not had much attention for a while, also a new DME relay, a good book, a long whilt just letting the car tick over and hopefully ......... I'll report back.
Thanks everyone
Peter
 
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