I have stumbled upon an issue that I can't seem to figure out. I have an Evo 8 that has a blue smoke issue. Basically what's happening is if left idling for an extended period of time, a quick tap of the throttle will generate a puff of blue smoke as the engine rpms drop. After that puff of smoke clears up, there's no more smoke at idle. After left sitting again and then given a quick rev, another puff of smoke will come out of the muffler. From what I can tell, no smoke other than the usually condesation occurs at cold start. When cruising or doing a pull I don't see any smoke behind me.

Any ideas? At first i thought valve seals but since it's not constantly smoking, I'm thinking maybe that's not the prob? Turbo is new and has zero shaft play. Intake appears to be clear of oil as is the turbo inlet. I don't feel any power loss either. A compression check came back clear too.

 

What turbo is it?

 

Just an Evo 9 turbo.

 

Piston rings are probably starting to get worn out and you're burning some oil.

 

Do you really think the rings could be worn even tho the car has under 60k miles? Compression check is 172-175 across all 4. I wouldn't expect the rings to be an issue so soon. If there were, wouldn't there be a constant smoking issue on deceleration?

 

Well you have to remember that there's mutiple rings on a piston. There's typically 3 rings, 2 of which are used for compression/pressure and the third is known as the oil scraping ring. The oil scraping ring has a set clearance from the cylinder wall and scrapes oil off the cylinder wall on each downstroke to push it back into the crankcase. If this ring gets worn down it could let excess oil get into the chamber and burnt.

But the more likely scenario I would think is that oil is pooling up in your intake/intake manifold while at idle. It can come out of the PCV area. A quick tap on the throttle increase the vacuum suddenly and sucks the oil into the combustion chamber for a little smoke puff.

Just add a catch can and you'll be golden.

 

I highly doubt it's rings, it very well could be a valve seal. Could also be the turbo, or crank case pressure causing the turbo to leak. My stock turbo smoked when lifting off throttle when it was going out..

 

Kinda wondering if the example epyon provided is the problem. I did try opening the oil cap while idling once and then gave it a quick rev. Smoke puffs did seem less apparent if even existent at all. It was kinda hard to see that night. Pulling plugs, I couldn't see any oil on the pistons. They appeared to be dry. No oil on the plug tips/threads either. Could be wrong but there could have been oil on the porcelain part on the first plug I pulled. I can't remember if I had oil on my hands or not when I pulled that particular plug (I have a tendency of trying to multi task).

Possibly crankcase pressure being a lil too high is causing the excess oil through the PCV at idle like previously mentioned. Gonna have to do a lil more in depth look at things.

 

Just pull your intake piping off and check the throttle body, if there's oil residue on it then you're getting oil in your intake. You could look for a way to solve the excess crankcase pressure, or just get a catch can. I know I've seen a thread about the evo 8/9 having excess crankcase pressure.

My MR2 has this issue since there's no actual PCV, it's just a hole in the valve cover that goes to the intake so it gets oil residue all over the intake.

Best of luck with figuring it out!

 

Thanks man. So far I've tried the test of shutting the car off and then starting it 30mins later to test the valve stem seals. No smoke on start up. I've also checked the intake and upper intercooler piping. No oil present in either. I'm now leaning towards the possibility of crankcase pressure pushing too much oil thru the PCV and into the intake manifold which later burns in the combustion chamber. Will probably do the valve cover pressure relief mod that TSComp suggests. Will also take it somewhere to get a second opinion on the symptoms. Fingers crossed!

 

There would be plenty of places for the oil to hang out in the intake manifold, so it wouldn't surprise me if that's the issue. Hopefully all goes well! Don't forget to keep checking your oil level since it's losing some lol.

 

2 months later, I still have a small smoking issue and not a clue as to what the problem is. I've tried venting the PCV and installing a 5/8" breather port. It's seems better mostly. I do however notice a trend. When I park on a hill/incline for a few minutes and then go to back up. As I blip the throttle in reverse, sometimes I will see the puff of smoke. Other than that, nothing else? Any ideas

 

Oil is pooling somewhere. You found none? Anywhere?
If not then seems logical to be internal.

This sounds familiar, I just can't put my finger on it and it's really bugging me.

 

Are you having to add oil between changes?

 

No.