laz74

Washed my car on Sunday late afternoon. Seems I got a little aggressive with the rear lid area...

About 5 miles into my drive later that night, I gunned it out of a toll booth and my dash lit up like a xmas tree...CEL flashing (indicating a rich misfire condition). Immediately sht my pants and pulled off to the side - car was idling really rough. I limped it home the next 10 miles, and car was stumbling big time at the stop lights to the degree that I had to throttle it a bit to keep it from dying. Finally made it home, plugged in the Durametric (pays itself off very quickly...) and there it was...Misfire cylinder 1, 3, 5, 4.

It seems enough water pooled in the intake air box to get drawn into the engine when I floored it causing incomplete combustion in 4 of 6 cylinders. I removed the intake, shook out the water, and opened it up and left it to dry overnight. Next day I reinstalled, cleared the codes, and it ran no problem.


CONCLUSION:
ALWAYS ALWAYS ALWAYS seal the ram air intake tube with rubber glove or similar before washing car.

(I hope this helps someone else avoid a nerve-racking experience)

jdjones2010

laz, I remember a couple of years ago I almost had a heart attack because of pretty much the same reason but mine was in the garage & we had some bad thunderstorms & raining & a day later I went to crank it up & holy crap I heard all the same noises your talking about. I just knew it was one of the two dredded issues, but sure enough after I let it set for awhile it dried itself up (ended up being condensation in the distributor cap) I had never heard of it doing that before & I called a indy & thats what he told me to check for, or just wait a few hours & see if it'll dry up itself. But, that was the First thing that came to mind was exactly what everyone's always talking about on here & your worst nightmare! jmo

MWP

While this post has been written ages ago, it saved me a trip to the Porsche dealership. Had my 993TT washed two weeks ago, and after a few kilometres I noticed something like a misfire while accelerating (fast). Check engine light came on immediately. CEL remained lit for the next few days, so I had an appointment scheduled at Porsche dealership for early August and kept the car in the garage.

I took the car for a spin earlier today, and the CEL was off. Must be the water has evaporated. So I decided to cancel my appointment and not bother on the issue anymore. Or shouldn't I?

wildbilly32

I don't know about a 993TT, but for the others...

Dennis C

Sounds like cracked coil pack(s) to me.

4Driver4

This was probably not the best strategy. Cats don't like raw fuel. ;-)

wildbilly32

...neither do cylinder walls.

dporto

I wish mine was so simple... 🙄

frisbee91

+1 on the cracked coil packs. That's exactly what happened to me. Misfires after washing or driving through a puddle. Replaced the coil packs. Easy fix. (but a bit pricy)

JB001

+2 on the cracked coils. It happens to me while driving under the rain (which is not common in Los Angeles...)