Rough idle + white smoke

[10sion]

Hi, I have an almost stock 91 240sx with the only mod to the engine being an msd and im having rough idling problems.

-The rough idle can be as little as 100 up and down to way jumpy going 1100-500.
-white smoke coming out of exhaust and its spitting little wet black droplets
-white smoke was coming out of spark plug hole #2 when i took out all the spark plugs
-spark plugs are black
-oil on plug wires

Im guessing its the valve cover gasket.

I really hope its not a blown head gasket. Last week when I changed oil it was black, it didn't look like chocolate milk. I don't know about the "sweet" exhaust smell though because I don't know what kind of sweet smell im supposed to look for. Doesn't smell sweet to me...

I can rev higher than 3.5k so I don't think its my maf.

Any and all help apreciated.

[aznpoopy]

oil on plug wires is just a little gasket that goes around the spark plug holes in the valve cover.

rough idle is probably gunk in your intake tract; particularly the idle air control valve. clean it out with some carb/intake cleaner. probably other problems as well. do basic tune up, clean off your engine grounds and battery terminals, etc.

black gunk out the exhaust... i've heard of that problem before but i don't think they ever came to a consensus on what it was. search for the thread... it was in tech a long time ago.

white smoke out the exhaust... could be many things. hard to diagnose over the net without seeing it in person. description is vague... could be anything from normal condensation on the exhaust, to bad injector to bad hg, etc... need more info.

if you're worried about a blown hg, one way to be sure. leakdown test. compressed air into the cyl, bubbles out the coolant = bad headgasket. good luck.

[ledzeppelin240]

Im guessing its the valve cover gasket.


Blown headgasket, you are burning coolant so that is why there is white smoke....That sucks. It could also be a cracked cylinder head.

I can rev higher than 3.5k so I don't think its my maf.

If the MAFS has a fault and sets the CEL it will not let you rev past 2500rpm because it goes into safe mode.