Runs great....small question...smoke?

[Exar-Kun]

OK here's the deal,

I have a pretty modified KA24DE in my 1993 240sx: the engine details are:-JWT cams-JWT cam gears-Ti valve springs/retainers-370cc injectors-walbro 255lph fuel pump-apexi s-afc to tune out the 37% larger injectors-intake-headers-exhaust

etc, etc....

I get a good bit of greyish smoke when I start my car, then it vanishes like 4 seconds later. my question is whether this is the choke/startup programming running with the much lartger injectors causing it to dump excess fuel into the cahmber on staertup, then being fine(no smoke during driving or revving in place, idleing, etc) whe the s-afc takes over and reduces the injector duty cycle?

thats my theory, also...

all fluids have maintained their respective levels(except i now have a PS leak from the pressure hose..I'll be fixing that asap), there is no odd symptom(idle, lack of power, etc) to speak of that I can notice.

thanks!(I just want to know if I should worry or not..)-chet

[Nismo_Freak]

Sounds like a ring that's not wanting to seal. Alot of forged pistons will do that for alot longer than 4 seconds. I don't think it's a big problem if it's a little bit of smoke and doesn't reproduce itself when driving.

BTW, fuel smoke is black or brown.

[PMan_S13]

Could be valve stem seals leaking a little bit of oil into the cylinders. Mine went out at about 100k miles. It would billow smoke at startup and then start to go away after a little bit.

Try doing a full decel from like 4000 rpms in gear for a few seconds. Once you hit the gas again see if you puff smoke for a second. All that vacuum could suck oil past bad valve stem seals.

You could always try replacing them if you didn't mind the work. Pretty easy, and you can get a full set of valve stems for like 20 bucks.

Maybe turbo is showing its age?

[Nismo_Freak]

Maybe turbo is showing its age?

Non turbo motor.

[Exar-Kun]

update-the smoke only lasts JUST after startup, and I get a small bit(very little) once I put it into gear and revv it a bit...after that, no smoke. run hard, hard dowshift, no smoke....

I jsut had some head work done a while ago..maybe 7 months? new valve guides, etc..I would assume they replaced the valve seals...

either way, it doesnt appear to be a persistent problem, and I'm fixing my PS leak first(dexron laking into the engine bay sucks...)

thanks for the input guys!-chet

[NateDogg]

I just had a problem with the Walbro upping the fuel pressure past stock.. You might want to check that out.

[s13sr20chris]

grey smoke makes me think coolant but your level would go down if that was it. if you are not consuming fluids and its all good after warm up... just chalk it up as racecar stuff.