smoke in valve cover

[driftaholic]

workin on my high compression KA24DE, tryin to figure out why it won't run right. my friend var stood behind the car as it ran (i have to stay i the car cuz it won't idle) and said first white smoke came out, then black smoke, then this gunky sooty stuff started flying out in little chunks.

then i turned it off and decided to see what was going on in the oil. opened the oil filler cap and all this whispy smoke came out. that doen't seem good.then i unhooked the hose from the valve cover to the intake to see what's up.

started her up and every time i revved it, var said white smoke would shoot out of that hose. it smelled like gas.

i played with the safc a bit, ran it 25% richer and 10% leaner. my a/f meter reflected these changes, but it didn't make a difference in idle or anything.

yargh. what's going on?

[DAEDALUS]

Smoke itself isn't that bad a thing. Whatever blows by the rings can come out the oil cap. But it sounds like you're running too rich. When you leaned it out what did the a/f meter say the ratio was? I assume it's a single sensor in the exhaust pipe (thus the reading is only an average of the 4 cylinders). I'd guess you're running lean on 3 cylinders but way rich on one from a leaky injector.

[s13sr20chris]

im with him. good thinkin.

[driftaholic]

i pulled off the fuel rail and turned the key, no fuel came out. then i cranked it and some came out. this means i don't have an injector that's stuck open, right? how do i know if one's leaky?i could just swap in my set of SR injectors and see what happens...

my a/f meter is just a crappy sunpro one with 10 leds. i have no clue what ratio each led means. and yes, it's a single stock O2 sensor.

thanks

[s13sr20chris]

well maybe we should diag the standard rich condition stuff. check coolant temp sensor, maf power, ground, and signal, etc. can you lean it more with safc? try that.

[driftaholic]

so i had my intake off, and i had to move the car real fast so i moved it without the intake on and it idled perfectly. like brand new.

so i went and grabbed the intake and plugged the mafs in and it started bogging and wanted to die.

i let it idle for a few minutes with out the mafs and got out to check things out (i wasn't ever able to do this before since i had to always be giving it gas for it to stay alive). there was so much white smoke coming from the exhaust (!!!!) and it smelled like gas. fun times eh?

so do you guys thing there's a problem with my mafs or what?
Modified by driftaholic at 12:11 AM 10/8/2004

[Nismo_Freak]

so i had my intake off, and i had to move the car real fast so i moved it without the intake on and it idled perfectly. like brand new.

so i went and grabbed the intake and plugged the mafs in and it started bogging and wanted to die.

i let it idle for a few minutes with out the mafs and got out to check things out (i wasn't ever able to do this before since i had to always be giving it gas for it to stay alive). there was so much white smoke coming from the exhaust (!!!!) and it smelled like gas. fun times eh?

so do you guys thing there's a problem with my mafs or what?

Modified by driftaholic at 12:11 AM 10/8/2004

Yep.

[danielmid]

Definately.

This might be a good excuse to get a tuned ecu and a z32 mafs. Just thinkin...

[driftaholic]

i just picked up my friend's old mafs and ecu so we'll see if i can get things goin.

another guy says that if the car runs without the mafs plugged in, then the ecu is going bad. can anyone confirm this?

[DAEDALUS]

Maybe it's different for your car, but I think your friend is wrong. I think it'll run in a limp mode, and with a CEL, but it should still run.

[driftaholic]

so i swapped mafs and it does then same thing. then i swapped ecus and it does the same thing.

[PMan_S13]

I'm more worried by all the stuff flying out the valve cover.. that's supposed to be minimal at best. Especially if this is a newly built motor? (From the high compression, I'm assuming?)

I had a KA motor once with 3 blown pistons and 4 bent rods and the thing still didn't blow out too much from the valve breather. The fact you have a lot of stuff just makes me worry that the motor may be (gulp) blown.

I'd really advice a compression check just to get that thought out of the way.

[s13sr20chris]

if another maf does the same thing but unplugging it helps...maf circuit is prob the issue. what you want to do is monitor maf voltage at the ecm. making sure the ground wire has good ground would also help if the ground has too much voltage drop.

[p00t]

my friend var stood behind the car as it ran (i have to stay i the car cuz it won't idle) and said first white smoke came out, then black smoke, then this gunky sooty stuff started flying out in little chunks.

Yikes! My first guess at an idle problem is vacuum leak or EGR sticking problem. I am leaning towards a vac leak because the engine will idle without the maf hooked up. This means its running in fail-safe, and is using preset values depending on throttle position, etc.

Did a repudable shop build this engine? im hoping yes . Did you put the engine together correctly? Timing chain marks and cam alignment are correct? Search the KA section if your unsure, theres plenty of info on that!

Get the engine running (not just cranking must be running) and check the timing with a timing light. Until you get it idling correctly try to time it to 15 BTC (this is 2nd to last mark on the right, looking from front of engine at crank pulley).

Also about the smoke... the stuff coming out the tailpipe actually sounds pretty normal the water from combustion is mixing with carbon in your tailpipe, and well carbon is black... plus theres god knows what in there if its been sitting for a while.

However the smoke from the valve cover is not normal at all. To me it sounds like the rings arent sealed yet since you havent run the motor at all..... and alot of blow by products are having a party in there. Smell of gas could be from incomplete combustion (bad timing again), or your timing could be fine but you may have a head gasket leak and all that is getting pushed in there (which might explain the white smoke but im unsure).

What was wrong with the motor before? If it was overheated you need to have the head shaved to make it flat, Im not sure if iron blocks need to be shaved as well. Just a new headgasket will not do. You can also check your coolant for bubbles or oil. Check the coolant level in the rad (when cold) and check to see if the oil is milky colored.

Make sure everything is at stock values if you have 370's in there set them at the proper correction % and leave it. If you continue to have the no run situation compression test it to find out where the problem is. A quick search will give you the rundown on that proceedure and you can tell if its a potential headgasket, valve, or ring problem.

Sorry if any of this is too basic i dont know anything about the history of your engine, or your mechanical skills. Best of luck tho, dont give up!!!!!

[driftaholic]

okayyyyyyy turns out i had to reset the ecu when i swapped mafs. so that's cool.

got it to hang onto idle just barely so i bumped the safc to +50% at 1000 rpms and now it idles very nicely. went and drove it around, and i must say i'm very impressed with the power.

now i just need to finish my e-fan install and fix my leaks and i'll spend the next 2 weeks seating the rings. if that goes well, then it's off to the shop for dyno tuning.

that's for the advice everyone!

p00t, you can read all about the swap here