boosted miata - Puff of smoke out of top of engine on deceleration ?

Hey Guys - 1.6 rotrex'd miata seeing about 10psi of boost. Under load (4th or 5th gear only) I'm seeing a puff of smoke out of the engine somewhere - I haven't been able to see where it's coming out of. I was having it spit oil in my face, but I've replaced the PCV grommet and upgraded PCV valve (the one from flyin' miata) and it doesn't seem to be doing that anymore. I'm having trouble debugging it since I can't really max out 4th gear on the street (that's when it happens), but it's really put a damper on my track days recently. Plug wire #1 seems to be coming out as well, but it seem related to wind, not blow by (I haven't refitted the hood on the exo since the supercharger) - but I haven't confirmed (nothing's shooting out when it does it, the boot just works out).

I'm going to start with a compression test - this was a low miles engine, but I never have checked the compression since it was running so well.

Any other ideas?

Is it load or is it decel? I'm wondering if it's the blow-off valve, which would imply bad things for your intake. Is there oil in the intake tubing? If so, where does it start?

In reply to Keith Tanner :

Hey Keith - It seems to be right after a hard pull on decel when the throttle snaps shut, but it always happens so quickly in the heat of the moment (I'm in 4 or 5th gear going into a heavy braking zone, lol - hard to pay attention) I guess I can't rule it out completely, but my blow off valve points straight down (in front of the engine) and it seems to be coming out in the vicinity of the PCV valve (but not from it I don't believe) and shooting up if that makes sense? It never happens that I've noticed in 1/2/3 under similar conditions - annoying.

I'm hoping to replicate it with a gopro pointed at it, but like I said, I'm having trouble replicating it not on track without getting into super ticket territory - I'm hoping to find some clear interstate and test it, but the exocet already draws way too much attention without me ripping it on public roads - ha.

Here's the engine setup, please excuse the state of affairs. 

I'll bet it's the BOV and the reason you only see it in 4th is the aerodynamics pulling the "smoke" up where you can see it. I'd pull some tubes off the intake to see what it looks like in there. Does it use oil?

In reply to Keith Tanner :

Roger - I'll take apart the intake side and inspect. It hasn't been using oil that I've noted, the PCV valve was spraying a good amount of oil before I fixed that, but even with that there was no noticeable drop on the dip stick reading.

Man I hope I don't have to do another engine swap. I'll just cry and give up.

Thanks for the advice as always Keith!

A little smoke never hurt no one. 

Time for a video whilst driving. Strap your favorite “IDGAF” recording device in the engine bay. 

In reply to Professor_Brap :

Lol - I hope this is the reality.... 

In reply to _ :

That's the plan!
 

In reply to Keith Tanner :

No oil at all on the intake side, dry as a bone at the intercooler pipe and throttle body. Camera time I guess...

Oil/smoke coming out of your catch can connected to the cam cover vent?  Maybe a bit of blow by vapor getting through the catch can?  Enough speed/air in 4th gear to suck it out the can?

In reply to M16ta :

Catch can is on the driver's side, but hasn't been collecting anything (though I haven't driven it hard since fixing the PCV which was previously spraying oil under boost). I've checked and you can blow air both ways through the catch can line.