Engine Cutting Out - 733i

[Gary Dietz <DietGa@xxxxxxx>]

Something quite strange happened to me a few days ago.  I got caught in a SERIOUS rain storm in my 1984 733i.  Actually, it had been raining heavily for several days.  I was heading down the highway (60-65 mph) with rain coming down so hard that the wipers would hardly keep up, and lots of big puddles tugging at the wheels.  All of a sudden the engine cut out, and then back in, very quickly.  Quite odd, and a bit disconcerting.  Over the next hour or so, as the rain continued to come down, the problem continued to get worse.  It got to where it would cut out so much that my speed would drop to about 40 mph, and would then take off again and be ok for another few minutes.  It would then start all over again.  Two or 3 times the engine would simply refuse to re-fire and I would have to pull over to the side of the road.  In those cases, once I had stopped, it would re-fire just fine when I hit the starter.  As I said, this continued for over an hour as I was trying to make my wa!
y home in this rain storm.  I finally drove out of the rain, but the problem continued for about another half hour after I was on dry pavement.  Then it mysteriously disappeared.  That was a week ago and it hasn't had the problem since.

I'm guessing that this was caused by water getting into some electronics somewhere.  It was definitely an electronics problems, since when the engine would cut out, the tach would immediately drop to zero RPMs, and would stay there until the engine re-fired.  When it re-fired the tach would immediately jump back up to the proper RPM reading.  I stopped a couple of times and peeked under the hood, but couldn't see any obvious large amounts of water in the engine compartment anywhere, so I'm wondering if it could be something underneath the car?  Anybody have any ideas on this?  I'd sure like to avoid this in the future!

Oh, one thing that I should mention, although I'm not convinced that it is related.  A few weeks ago I discovered that the plastic cap that covers the engine diagnostics plug had fallen off and disappeared.  I worried a bit about having that plug exposed, but then forgot about it.  But, this is the first thing I checked when I started having this problem, and there was no apparent water anywhere near this plug.

I should also say that I have driven this car for 3 years now, and have never experienced this problem before (or since).  I've driven it in some pretty heavy rain too, although this was certainly the most dramatic storm I've ever been in.

Anyway, any suggestions would be appreciated!

Gary Dietz
1984 733i
1980 320i
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