I'm in Northern California...so I havent had that much rain yet, but a week ago while driving in the rain all of a sudden the exhaust note of the car changed to sound like the header fell off...and there was some vibration I could feel through the shifter knob. However, before I could pull over and check things out, it cleared up. Then today while driving my WRX during heavy rain it reoccured. And again it cleared up as I drove into an area where the rain wasn't coming down as hard. Anyone eard of something like this? any suggestions?

Jeff

Besides the loud noise and vibration, were there any other symptoms? Did you have any hesitation or other sensation of intermittent power loss? Were you accelerating hard at the time? Last but not least, do you have a bra? No not you, on the car:lol:

no, I don't have a bra on the car. I was moderately accelerating. I do have a full Scooby Sport exhaust. since both times it was in heavy rain I didn't know if the engine had water in it...although I couldn't figure out how that would cause this problem.


Jeff

Someone with a full Scooby Sport Exhaust system is also likely to have "upgraded" their intake system. And an intake system that ingests too much water might account for the symptoms described.

As far as hydrolock goes, the phrase "...too much water..." may be applicable, but it wouldn't take much water mist on the heated element of a hot wire/film mass air flow sensor to cause it to give a false reading on the high side. Would the resulting overly rich condition cause the Scooby Sport exhaust to sound louder? I'm not sure, but it could certainly cause other problems. <<EDIT: I guess excessive amounts of unburnt fuel reaching one of the hot cats could result in some strange sounds. Especially if that particular exhaust was designed to accentuate certain frequencies. japps - Were the sounds you heard anything like a backfire or popping sound?>>

As far as stock versus aftermarket intakes go, I would say the stock set-up is at least as likely to ingest water, if not more so, than. Quite a few of the aftermarket units, that I have seen pictures of, replace the stock air filter box with a cone filter. That cone filter draws it's air from under the hood as oppose to the stock set-up that draws air in from up front by the grill.

On my completely stock WRX wagon, I've had three "rain events" where I've had hesitation like symptoms. Each event occured under full throttle acceleration, while it was raining, and with in a few minutes of starting the car up after it had been sitting out in reasonably heavy rain. One of the events threw a P0103 DTC.