EB_1920

Washed the car yesterday (exterior only, not the engine bay) A few hours later, I try to start the car and it won't start. It turns over, but it sounds/feels like only a few cylinders are firing. Not enough to keep it going.

I checked the forums and found a post that suggested it might be a blown fuse, specifically the fuse that controls the ignition coils. (http://www.renntech.org/forums/index..._1#entry170794). Unfortunately, I checked all of the fuses in the fuse box in the engine compartment and all of them look okay.

Any suggestions on what I should check next?

I tried to run my Innova OBDII scanner, but it didn't find any codes (maybe this particular scanner doesn't work with the Cayenne).

By the way, I should mention that the car has had a rough idle. The previous owner said that he replaced the coils and plugs, but I'm not so sure about that. Could a cracked or melted coil(s) cause the no-start issue?

Thanks for your help.

flintworks

Washing the car should not affect anything in the engine compartment. I have seen ignition coils fry and even cause damage to the engine harness. This would definitely cause the car to run rough and eventually not start. Considering you need air fuel and spark for an engine to run if you don't have spark it will not run.

Andy E.

Actually, in some cases it can.

Last year, my wife's Benz suffered from a dislodged sunroof drain tube which much to my surprise, is routed ontop of one of the many onboard fuseboxes. This wreaked havoc on many of the onboard electrical systems.

I'm unsure about where the sunroof drain is routed on the Cayenne but I wouldn't be surprised if it's near a fusebox or connector as they normally run down the A & B-pillars.

turbo23dog

We had similar problem in our 06 CS. Starter spun the motor but it would not fire up till after many tries. It turned out to be a check valve in the fuel tank that went bad, causing the engine to flood. ie: too much gas. Its a CPO vehicle and the repair was covered under warranty.

EB_1920

Update: I changed the fuses for the ignition coils and the oxygen sensor. The oxygen sensor fuse looked a little dark. Not sure which one solved the problem, but the car starts now. Very rough idle though. I'll probably just go ahead and change the coils as a preventative measure. No idea if the oxygen sensor had anything to do with my problem or not. Gonna do some more research on that.

snappy

Did they wash it with a power washer? Did it spray water from the bottom up?
Did you look at the O2 sensor?

my guess is o2 or maf..

mudman2

I would suggest looking at the coils