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Location: Cary, NC
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Idles fine then suddenly drops and cuts out

My S2 has 100K miles. Recently, I have had the car stall at idle. If I come to a stop light, the revs hold steady at around 800 and unpredicatably, the bottom will drop and it dies. Oddly, on some days it does not have the problem. I tried feathering the throttle to keep it alive but it coughs and sputters. I tried keeping a steady rev at 3000 to see what it does, it fluxuates off and on a difference of 500 rpm or so. The symptoms appear to be more fuel related than electronic but can't be sure. On other threads of this topic, there are dozens of suggestions. Anyone have a good idea which one to start with?
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Old 09-25-2003, 09:47 AM
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Grounds.
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Old 09-25-2003, 10:21 AM
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When I was a kid, my parents took me to the beach and I got lost. I asked the cop if he thought we would find them. He said "I don't know kid, there's so many places they could hide" - Rodney Dangerfield

Likewise, there are so many places a bad ground can be hiding (if that's what you mean). Where would you start given the symptoms?
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Old 09-25-2003, 11:02 AM
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On my ancient '83 the fuel pump relay would cause this kind of problem. Let it sit an hour and it would fire right up like it had good sense.

I've also had to work on the panel that holds the fuses and relays. It is so old the plastic had cracked and broken in several places, and there was 'spritz n sparken' where there shouldn't be...

Good Luck
Old 09-25-2003, 11:24 AM
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Check where your speed and reference sensors plug in to the bracket on the back of the engine block - work them in and out a couple of times to clean them off.
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Old 09-25-2003, 11:43 AM
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Your Idle Stabilizer Valve is sticking - it's getting old.

Also, just about the same time, the Throttle Position Switch will start acting up. These two going bad at the same time can cause lots of problems, including the one you have.

944S Boyeee
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Old 09-25-2003, 11:58 AM
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...and dont forget to check for good old vacuum leaks
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Old 09-25-2003, 12:07 PM
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Excellent, thanks all. I'll check each of these and let you know what I find.
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Old 09-25-2003, 12:19 PM
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does it go away when the car is hot?
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Old 09-29-2003, 09:18 PM
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I concur with profsr. Mine had the same symptoms and it was speed and referance sensor connections. Bend the copper connectors on female plug out a bit with a tiny screwdriver to make sure male connects properly and clean all.
Old 09-29-2003, 11:11 PM
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I had recently suffered pretty much the same thing with my newly acquired '88 944S. It would randomly decide that it desperately wanted to stall, however if I tried to keep it alive by giving it some revs it would aggressively hunt up and down by around 1000rpm. Try driving that!

After the Idle Speed Valve was disconnected the problem seemed to go away for about a week but soon returned. I have just had a blown ground in the ECU repaired, as well as having the car retuned and now I am pleased to report that all is well. I however, I also had a bunch of bad grounds elsewhere, definitely worth checking into.

Good Luck
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Old 09-30-2003, 07:42 AM
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How does one get at the speed, etc sensors? Can you get at them from the top of the engine?

Jeff
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Old 09-30-2003, 08:12 AM
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