good hands

At my last race weekend in NJ I was black flagged several times for getting an occasional puff of greyish smoke out of the rear of the car. Seems like it only did it during load as we can not recreate it on the Dyno. We have done just about every test imaginable. Compression, leak down, no codes being thrown, engine has been scoped, no leaks, oil is good, water is good. All the numbers have been excellent.

It has the motorsports AOS that was installed just 2 years ago. I have not heard of these going bad but that is the hunch of the mechanic. Any thoughts appreciated.

Car is my 996 race car. Stock 3.6 engine.

Steve113

I am no expert but sounds like blow by of some sort. Figure out if you were exciting a corner and if it was left or rights

Paul 996

You can't recreate it on a dyno since there are no lateral g forces involved. The AOS is most likely on its way out. You can test the crankcase vacuum if it is excessive you know that it is the AOS.

Engine crankcase vacuum is normally around 4-7” (Inches) of water. When the oil separators fail the crankcase vacuum can rise to 9-12” and even higher. The other thing you will see if the car running abnormally rich.

While the 986/987s generate a massive smoke screen the 996/997 seem to make a puff here and there but the problem is you are ingesting oil into the intake and will foul up your plugs, etc.

Why on earth would they black flag you for a "puff" of smoke? A smoke screen I could understand.

Hope this helps.

-P

morsini

Environmentalists

good hands

Car running a bit lean actually according to dyno results.

d15b7

hey Scott is there evidence of oil in the intake tract? do the plugs look at all 'ashy'? I had a car that was ingesting lots of oil and it was obvious in the intake tract (very oily) and the plugs (especially the electodes) looked white and ashy due to all the oil being burned up.

Todd
ReidSpeed

Veloce Raptor

Hey, Puff Daddy, I agree--replace AOS and check intake tract and plugs for evidence of oil fouling.

sig_a

If it were oil in the induction system wouldn't the smoke be blue?

mglobe

AOS is the most likely candidate, but also check your oil level. You could be slightly overfilled. In my opinion, if you are at the maximum mark, you're overfilled. Most times you will see smoke on startup when overfilled, but worth checking

good hands

All checked. All clean.

plugs fine
oil halfway up the stick. No smoke at start up. Can't recreate smoke on dyno.

FrankyV

The scruts were all over this at the NJ race, they black flagged me as well and I could find nothing wrong with the car, not even a drop of oil leaking onto the exhaust. My guess is someone who was just puffing at a recent race caused an incident.

Sean F

yeah, maybe it had something to do with someone oiling half the track and not noticing the giant cloud trailing their car. pretty long cleanup after that.

FrankyV

My black flag came at the end of the first practice session before the track was oiled down.

Gary R.

Track was oiled down the day before at the DE Frank, closed the track for over 4 hours...

BostonDMD

Yeah, 4 hours wasted of track time and the guy said he forgot to tighten up the oil cap........ unbelievable....

Scott, I hope you get your issue resolved soon.....