NoMoreWRX

A bunch of smoke came out the back of the car. I figure it was unburt gas or maybe a sign something is wrong. Any ideas? it was not in gear.

Don't ask me why I can't even explain.



Thanks,
-Ed

jguerdat

What color smoke? What did it smell like?

slalom44

If anyone revved my car to 8000 rpm while in neutral, I'd .

If you started up the car in cool weather and idled for 10 minutes, there is a possibility that you have accumulated some condensation in the muffler and when you gunned it, the water vapor came blasting out of the back. That's the best-case scenario. The smoke would be white, and smell like steam.

Coolant in the exhaust also gives off white smoke, and would be the result of a blown head gasket, or possibly a cracked block.

If the smoke is blue and smells like burnt oil, then you could have one of a number of problems, none of which are good. Most likely, it would be a bad cylinder.

So Jguerdat's question is very crucial in diagnosing the problem. What color is the smoke? How is the car idling afterwards? Is it misfiring? Can you even start your car? How did it run before you did this?

NoMoreWRX

runs fine, start's fine.
only 4k on the odo,

After I got the car in gear no more smoke.

Color, hmm..... It was night so very hard to tell, it was thick and smelt like exhaust gases.

Thanks,

-Ed

NoMoreWRX

There are times when it's valid to rev the engine under no load. For instance, approaching a 30mph exit speed corner, to get into first for the exit you would rev match to about 7.5 k. No load until you release the clutch.

This wasn't one of those valid times, but it is something that comes up.

It was humid last night around 50, my only guess is it was fumes that were sitting in the exhaust at idle.

maybe the ECU dumped fuel into the engine because of the rpm?

Thanks for any help,
-Ed

mxt_77

If it was black... probably just unburned fuel.
But... don't rev to 8K in neutral. It's not nice to do that with no load on the engine.

Gernby

Maybe your spark plugs were fouling from idling for so long. It may have just been a bunch of soot building up in your exhaust.

Do you have colder spark plugs? Is your ECU backup fuse missing or blown? I have found that my colder plugs foul pretty easily when the ECU backup fuse is missing because it runs rich.