Smoking only after fully warm

[T-Flexx]

This is a pretty strange one that I am having a poor time trying to discover what is the issue.

It all started when my ecu started to fail. When ecu started to fail the CEL would kick on and the car would sputter and almost die, then it would be fine and not store any codes. Before I discovered the ecu was toast the car did it's little "I hate my life" stutter and then gave a huge back fire (right in front of a grade school). I didn't drive it after that until I discovered the ecu was bad, burn hole in the ecu under capacitor. Replaced ECU car started up just fine and ran well. The issue now is once the car is at normal operating temp smokes starts to come out of the tail pipe. At first it wasn't really distinguishable on color but now it is definitely oil smoke.

To track this down I have done compression test 157 on the lowest and 165 on the highest so good there. I pulled intake and checked for shaft play. No in/out or up/down very small side to side. Pulled DP and checked for oil. Pulled intercooler inlet and J pipe. No oil any of these places. I also pulled the oil return line and it was wide open.... I started to pull the manifold to check there but got stuck ### the oem "ring" is still in between the manifold and turbo.

I am running out of ideas on where the heck the oil is coming from.

 

[mantega4g63]

i vote valve stem seals

 

[T-Flexx]

Is the best way to determine valve stem seals by oil in the manifold? Also if it was the VSS wouldn't it smoke at start up after sitting for a while because it would drip down onto the piston??

 

[Kod]

Valve seals is my guess too.

Engine warms up seals then get warm / softer oil gets by them easier is my shot at it.

 

[92AWDHX40]

Looks like youll have to pull the head and see.

 

[03GS-T]

My question is, why would a failing ECU cause the seals to go? Just leaned out the fuel? But wouldnt the backfiring be caused by richness?

 

[BogusSVO]

Kod has it backwards, when the seals are hard, they do not seal against the valve stem well.

When they are hard, the oil slips by easier.

Since it is only smoking once up to op temp, I am going to say rings. Not the 1st and 2nd rings, you are holding compression well enough.

The oil scrapers have failed, 3rd groove. What happens is the drain back holes in the oil scraper lands get clogged, holding the oil in the rings instead of draining to the inside of the piston. or the oil rings are just stuck and can not flex in and out of the piston.

The oil is thinner when warm, so the more sticks to the cylinder bore, making its way past the scraper rings and into the combustion chamber to be burnt.

Improper oil changes, and extended rich conditions will lead to the clogged drains and/or stuck rings.

Also a extended over heating issue can fry the rings causing them to loose there out ward tension.

The bad ECU could have lead to an over rich condition that clogged/stuck the scraper rings. When the new ECU was installed and it went back to running correctly, and you could not tell what color the smoke from the tail pipe was, you were burning off the excess fuel deposits from the piston/combustion chamber (black smoke) then just leaving you with the blue smoke of burning oil.