Cutting out in heavy rain

[FernandoBunster]

Just drove back home from Manhattan in heavy rain and the car cut out on me three times. Wouldn't idle and ran rough with foot on the accelerator. After letting it sit for about 10 minutes each time, it would start and run normally. The last time it ran without a hitch for about ten miles the rest of the way home.

I'll check the obvious; ignition wires (high performance about a year old) and distributor cap. I've already checked the ECU and it's bone dry. Is there anything else to look for. BTW both fuel pumps and fuel filter are new. Can a bad connection plus water on the O2 sensor be the cause?

[euroshark]

The O2 sensor on my 535is crapped out after driving through some deep water. I was getting the same symptoms plus it wouldn't run under and sort of load. I unplugged it and the problem went away, and the new O2 sensor has been fine ever since. Its worth a try!

[carsnplanes]

Just drove back home from Manhattan in heavy rain and the car cut out on me three times. Wouldn't idle and ran rough with foot on the accelerator. After letting it sit for about 10 minutes each time, it would start and run normally. The last time it ran without a hitch for about ten miles the rest of the way home.

I'll check the obvious; ignition wires (high performance about a year old) and distributor cap. I've already checked the ECU and it's bone dry. Is there anything else to look for. BTW both fuel pumps and fuel filter are new. Can a bad connection plus water on the O2 sensor be the cause?

Fernando, I've not heard of an O2 sensor causing the engine to actually die. If it's cutting out completely sounds ignition related. If it sounded like it was running rough, or on less than 6 cylinders or crossfiring, then maybe the cap or wires like you said.

[CW6er]

Check the Coolant Temperature Sensor and both Reference Sensors, as well as their plugs also.

[Bentsdl]

My guess would also be the reference sensors, especially because you can start it after waiting some time. A common symptom

[FernandoBunster]

Thanks to all. Now that I think of it this happened once before a year ago on August 16 in another torrential downpour ( I remember because it was the day of my daughter's wedding). Will check and or replace all suggested components.

[Rick in Denver]

When I first got my black 6, I had that same sort of problem. In my case it ended up being a missing fuse box cover. Maybe yours is leaking?

[635 Red Baron]

i had the same problem in the rain and it turned out my O2 sensor was just wet. unplug it and let it dry for a couple days and you should be good.

[JW767]

Sometimes water can sneak in from the windshield and end up leaking down on the DME.

[FernandoBunster]

Well I just had the new OEM O2 sensor changed so I guess I'll have to wait for heavy rain. BTW there are no leaks into the cabin since I had a new windshield seal installed a few months ago.