Evo X 4B11T Smoking

Thought I'd try and get some clarity before I go the whole hog and pulling the engine for a rebuild....

I have an Evo X with the 4B11 which was forged about 25k miles ago but it's burning some oil. I've done a compression test which is a little low at 115PSI but all 4 cylinders are equal and I believe the car has cams fitted which may partly explain the low reading. Leakdown was quite low at only 5%.

The engine is breathing a bit, with stock CCV and PCV. The standard PCV wasn't fully sealing so I expected it was pushing boost into the crank case and straight out into the intake. New PCV installed but still smoking/ using oil. I installed a catch can between the cam cover and intake to capture some oil but it doesn't seem to have any oil in it. I removed the PCV and vented both outlets to a catch can and let this vent to atmosphere.

As in usual fashion the turbo and manifold had cracked so I have installed both new items- and the old turbo was cooked once removed.

Here's the bit that gets me- lets assume it is worn bores/ rings, surely this would be smoking consistently when coming on boost? However it is always intermittent. Sometimes there's little or no smoke when on boost and other times it's a trail of blue.

Any thoughts as if it were worn bores surely it would smoke all the time?!?!

Are the bearings in the turbo oil fed? If so, could be turbo issue, not the engine.

Edit to add I’ve installed a brand new turbo-

so it’s not that, sadly.

it couldn’t be a valve stem seal or something along those lines?

it’s very odd, if I lift off and got WOT throttle again it can often stop/ start smoking.

A few possible reasons for smoking engine I came across in my experience with Evo

1) cams with very high valve lift caused retainers to contact steam seals acting like an oil pump. I had to lower valve guides a little bit down in the head.

2) steam seals were not installed properly but a little bit to a side making small gap between valve and seal allowing oil to escape. I had to adjust their positioning.

3) Turbo vent system- the hosees from valve cover were routed to the catch can in a way that was preventing air from moving freely that resulted in excessive crank case pressure that in its turn didn't allow turbo oil to drain quick enough- it was partly going to turbine hot side instead of fully draining to the crank case. I figured it out when I loosened those hoses from catch can to the open atmosphere...

Thank you for the reply, was this on a 4G63 or 4B11?

The lack of consistency is what’s really confusing to me.

I personally worked on 4g63. By the way - I just recalled another case- piston rings gap was too large and the car was smoking too.

Inconsistency with oil smoke usually comes from stem seals. When car is idling some amount of oil collects inside of intake runners or even intake manifold and progressively gets burnt out when the engine is under the load. And it goes in circle.