Boom!!! White smoke

[Rustyregal]

Well I've been wrenching away at this thing for about six months now. Its been a lot of fun and the car runs real smooth except....... From tithe to time while cruising I would develop a slight hesitation at a steady cruise. Not much just real quick,about a 2-300 rpm drop. It started again a few days ago so I began trying to see what made it better or worse.

So I dropped it in to drive and it became a bit more pronounced. So then I slowed down to around 40mph and dropped in to 2nd in an attempt to load it a bit more and see if I could track down the conditions that would induce it. Then BOOM three consecutive back fires out the tailpipe and a tone of white smoke. I got it up and running again after a good look over and got it home with a code 34 & 41.

I changed out:
Cam sensor
Ignition module
Spark plugs
PCV

Now on to it. Only at WOT will I get white smoke. I followed behind the car and it is odorless. Removed the turbo and slic found no oil. Nor did I find any residue in the down pipe.
A compression test revealed a cylinders but #6 at 145-150 with number six reading about 135. And it looks visibly cleaner with a bore scope. I'm just wondering why its only at WOT when it smokes. All opinions are welcome.

 

[turbo nasty]

White smoke....Headgasket IMO. Maybe only slightly compromised and with the elevated cylinder PSI's of boost is when it leaks.

 

[blackgn1]

I think headgasket also. Could be leaking under pressure. Do a leakdown test.

 

[RunninShine231]

i second leakdown of all cylinders. time consuming yes but critical if you want to know whats happening in engine. good equipment also helps
a combustion leak detection kit can also be used in cooling system to varify combustion gasses are indeed entering system

real question what caused that cylinder to "go dead".. might look into injector flow.. she may be leaning out.

another thread

 

[Rustyregal]

Changed the PCV and smoke disappeared.