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Intermittent stalls

 
Old 10-13-2009, 12:32 AM
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Tom Rathjen
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Default Intermittent stalls

Hello. Well, after several months of my '82 928 project car running very smoothly, a frustrating problem has surfaced. Four or five times in the last three months the engine has stalled. (A sudden and complete stall....not sputtering.) One time it immediately restarted, but the other times it has not restarted until it sits for a couple hours at least. The stall has occured while idling a couple times, and also it has occured while driving along at a steady speed (requiring me to coast off the road). One time I had to have it towed home (and then, of course, it started right up).

Unfortunately, I have not been able to do very much meaningful troubleshooting or diagnosis while the problem is occuring (since it of course never occurs at home). That is, the problem is gone and the engine starts and runs fine by the time I have been able to get out to the car with tools. However, I am almost certain it is a "no spark" situation, since I have smelled fuel when cranking it and I have verified the fuel pump is running. I had the ECU tested, and it tested good. I also replaced the ignition control unit since it appeared to have been tampered with and I didn't trust it. But the problem recurred again. The coil is almost new, as is the distributor rotor. The fuel pump relay is new, and I recently replaced the fuel injector relay as well. I have verified good continuity of the "green wire" from the distributor to the ICU connector.

I have been searching through old posts, but haven't found anything that seems to match this. I was particularly interested in some posts about flakey alarm systems, but I don't believe my car has either the factory one or an aftermarket one.

So....I'm interested in any suggestions. It is very frustrating to test and diagnose this very intermittent problem since everything is normally working so good. Yet the car has now become unreliable.

Thanks
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Old 10-13-2009, 12:40 AM
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Chris Hansen
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Is the green wire old? Mine looked good, but the plastic ends were crumbling, causing a similar issue to the ones you are describing.
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Old 10-13-2009, 12:56 AM
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Tom Rathjen
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Yes, I'm sure it is old. But the ends seem OK and I tested continuity all the way from distributor end to the sockets in the connector that goes in to the ICU...while wiggling the green wire to look for an intermittent break or short. It seemed to check out good.
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Old 10-13-2009, 07:43 PM
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I can also add that I did manage to check the engine temp sensor "on the spot" at one point when the failure briefly occured. (Just pulled the connector and jumpered it.) Made no difference, so not the problem. (This was something else mentioned in the possibly relevant posts I've looked through.)

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