Smoke show

Year/Make/Model: 2007 Mazdaspeed 3
Mileage: 218k miles
Location: fuckin Arkansas
Concern: intermittent smoking coasting (high vacuum)
DTC's: yes
Modifications: HPFP, Cobb intake, turbo-back catless exhaust, tuned on E42 by Phate
ECU/Tuning Software: Cobb AP
Tuner: Phate
Is the concern intermittent? yes
Can you duplicate the concern? not reliably
Recent Repairs: none relevant; replaced spark plugs and coil packs
Correction:

The shitbox has been pretty great, all things considered, since I bought it back from my friend in November; however, it's using oil intermittently. Like for the first 3k miles, it didn't use any, but for the next 2k miles it used almost 2 quarts. I check the oil weekly, and this occasional oil loss continues. I have seen it smoking (and smelled exhaust in the cabin) after driving somewhat spiritedly while coasting in gear, coming to a stop. Also, once in awhile when I start it (not often). I just changed the oil and I'm using Tibodyn 15W-40, hoping that will help; previously it had 10W-30 Mobil One. In any case, I know I probably need to replace the PCV valve, but why would this oil usage issue be intermittent?

I bought some AC Delco top engine cleaner to soak the pistons; I plan on doing that at my next oil change.

 

Coasting in gear is likely piston rings

 

Failing Pcv?

 

Dwhat happens if you let it idle for a long time?

 

That was my thinking as well, especially considering the mileage. Need to check compression.

I've never noticed it smoking after idling awhile; I've probably idled 15 to 20 minutes several times. Even over 30 minutes before and no noticeable smoke.

 

I doubt it's pcv then though I would still check it. Could be rings valve guides etc.

 

Have you had time to do the AC Delco top engine cleaner?
If so what were the results?
It does seem like rings, Hope you can get it better with the top engine cleaner.

 

This weekend or next week. I can't seem to get motivated.