Vacuum caused by decel would pull oil in from the PCV or breather. It does so as part of normal operation. However, the amount is virtually nothing.

If it pulls in more than virtually nothing...then...you get smoke.

If there's a situation in which liquid oil exists at the breather or PCV port...then...yep. Smoke.

Check your compression. Hopefully not..but maybe you dropped something into one of the cylinders when you did that plug swap and it caused some scratches.

Best case scenario is that you just have some sort of breather issue.

Valve seals aren't a huge deal. It would be a day's job. But not that much stuff has to come apart.

 

Smoke right after a hard deceleration is most likely valve stem seals. But, the OP's car is showing smoking at idle. Or right off idle.

I'm still not convinced that all four plugs are oil fouled.

 

If my AP2 sits at idle for more than like...5 mins, it will start billowing an alarming amount of smoke.

It burns almost no oil during regular or track use.

But I get a ton of crankcase blowby in the valve cover. This car's primary purpose is for the track...which kinda necessitates catch cans. I had to use a lot of cunning and recirculate the cans...or I would die inside the cabin from fumes.

The entire situation is inexplicable. So...I've just gone on with my life and let the car live its life.

This doesn't help the OP. But it sure makes me feel better.

 

^Sounds like my car. Doesn't burn much oil if any during a track day. No smoke after normal periods of idle or engine braking. But if it idles for an extended period of time, smoke cloud. Scared the hell out of me the first time.
It's an ap1 engine with 2006-09 valve cover and PCV. Breather to intake arm, no catch cans yet but on the list. Totally stock longblock, runs great, makes all the power it should, has about 120k miles.

Still true right off idle. Sure, it will pull more vacuum during engine braking.... and at idle throttle is still closed and intake stroke is going to pull air through path of least resistance. Engine is still pulling a lot of vaccum unless you have huge cams, big vacuum leak etc.

 

I had this old BMW 2002Ti that needed top end work. I would be coming down one of those steep inclines out of Lake Tahoe. No problems going in 2nd or 3rd down the hill. BUT at the bottom, when I gunned it --- looked like this. I'd tell my passengers I was setting a screen to hide from rice rockets.

 

Hmmm the whole smoking at idle people are seeing is interesting. I could let mine idle all day like a truck driver taking a nap and never see any smoke. But of course have seen it on some autox runs and track before installing a catch can.

 

MINE WHEN IT HAD BAD RINGS DID THIS 24/7. THOUGHT I WAS SPYHUNTER, LOL

 

^That looked like mine at an autocross event when I forgot to empty the catch can after a previous event and a track night event That can was full to the brim and people working course thought my motor was about to go lol

 

Oil sample was taken and will be sent out to Blackstone labs. I have another reading from back in 2019 to compare to. That'll provide an explanation if there is increased wear material in the oil.

As a side note, these odd issues is what kept me interested in this platform for over a decade.

 

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