Subaru 2004 Outback backfire or gunshot? Rainy Oregon

subaru
outback

#1

Start up sounded like light pop, then driving down the road a mile I heard what sounded like a gunshot. Been raining a lot in Oregon. Could water in my electrical or spark plug area cause this? Some areas of hood around engine hood have gaps where water can get in. Left backlight has area that rain gets in. Hints welcome please. Car ran good after for 15 miles. No reduction in power.


#2

Could have been a backfire. Say one plug stopped sparking for a short time. The fuel and air charge which is injected & intended for combustion, instead is just is pushed out of the cylinder into the exhaust manifold and tailpipe, where it ignites from the hot exhaust gasses from working cylinders there. Bang. Bang. Bang.

Reminds me of the story Ray (of Ray and Tom, the Car Talk brothers) tells. As a teenager, for entertainment he said he’d take a drive sometimes with his teenage friends through the airport tunnel there in Boston. Once in the tunnel he’d purposely turn off the ignition briefly, for this same purpose, to get raw fuel into the exhaust. Upon turning the ignition back on “bang” “bang” “bang”, and inside that long tunnel it must have been pretty impressive.


#3

i am voting for it not being a gunshot


#4

It hasn’t happened since the last big Oregon rain storm. Now I have an even bigger problem with my lovely lemon.


#5

Could have been a gun shot though. Things are pretty wild out there. I would guess too that its an ignition problem caused by moisture. I would have said timing if it hadn’t cleared up. Could also be a fuel/mixture issue caused by a sensor. So the ole spray bottle test in the dark looking for sparks might help isolate it.

Wife came home one day saying she heard something hit the car. I looked it over and sure enough there was a BB sized impression in the quarter panel. I thought it would be easy to fix but the metal was so stretched, it had to be filled, so then of course you have more painting to do, so turned out to be a little bigger repair than I thought. At any rate check around the car for any unusual impressions.