Blue smoke after boost....turbo seals?

[tooch]

When I give my car a good boot, say in 3rd gear up to around 10PSI, when I back off or change into 4th, I get a huge puff of blue smoke out the exhaust. Would this point to rooted turbo seals causing oil to be sucked through, or is it likely to be something more sinister?

[Adash=P]

Looks like its overfueling. Do you have a BOV fitted?
If oils burnning, the smoke should be white.

[tooch]

Yeah I have a BOV, but isn't blue smoke oil? Over fuelling would more likely be black smoke yeah?

[Jorrs]

fuel being burnt is a dark grey
yeh i was thinkin oil

[whatthe?]

Yeah I have a BOV, but isn't blue smoke oil? Over fuelling would more likely be black smoke yeah?

Blue is oil though sometimes hard to tell blue from white in the rearview. if it was rings you'd be getting it under load, not at gearshift

[o_man_ra23]

There was another similar thread, i think it was titled, smoke when coming off boost, or somtthing similar. N e ways, i went into great details to describe what happens when coming off boost. I assume that you have a plain bearing turbo, in which case the oil seal for the turbo on the exhaust side has a lot to do with the pressure in the exhaust turbine. When you come off boost, you have the turbo spinning, sucking air from the exhaust manifold, which cannot supply air because the throttle is closed. Your BOV is helping the turbo to continue spinning, therefore sucking more air. This creates a vacuum in the exhaust manifold, which sucks the oil seal which works on atmospheric pressure to seal which in turn draws oil from the turbo and ducts it out your exhaust. If you change your atmo venting BOV to a plumback BOV, you will send the intake air pressure straight to the exhaust manifold, which will allow the turbo to keep spinning freely to reduce lag, and also it will equalise the pressure in the exhaust manifold, thereby continuing the seal for your bearing which is normally created by the pressure made by your combustion process. In short, an atmo venting BOV, while also creating an irritating and poofterish noise, also kills oil seals in plain bearing turbos.

farck the BOV off and replace with a factory style plumback BOV and see if that works... otherwise you could spend thousands of $$$$ on turbos and other products which will help in all of about no ways.

Cheers, Owen

[whatthe?]

If you change your atmo venting BOV to a plumback BOV, you will send the intake air pressure straight to the exhaust manifold
Cheers, Owen

Dont plumb backs vent back just before the compressor side of the the turbo? How does this equalise pressure in the exhaust manifold? Not saying youre wrong, just saying I dont understand. i use a plumb back and it definitely doesnt vent to exhaust

[limbo]

Your right, usually oil burn comes from loan.
Try checking how much fuel is being given on Load release. I can't rem what the setting is called. Its the fuelling on deceleration, it might be too rich thus the blue smoke, might be from richness. Have you had the car on a dyno with an AF metre graph? This might be able to check and identiy any problems

[mullett]

From what I've seen so far in toying with cars, oil burnt almost always comes out white, and fuel is blue or black (depending how much)...I could be wrong here. and if you've got an atmo BOV, the ecu will dump fuel in when you back off in a hurry, because it reads air going in (which is vented), and pumps fuel in to suit....

[whatthe?]

From what I've seen so far in toying with cars, oil burnt almost always comes out white, and fuel is blue or black (depending how much)...I could be wrong here. and if you've got an atmo BOV, the ecu will dump fuel in when you back off in a hurry, because it reads air going in (which is vented), and pumps fuel in to suit....

Not sure about that one,

Plumb back + AFM = air returned between AFM and Compressor = no ecu reading
ATMO + AFM = air returned to atmosphere = no ecu reading

where does the ecu get a signal to run rich?

[tooch]

Interesting read about the BOV, the only thing is that it has only recently started doing it. The BOV has been on the car for probably a year now, and only in the last week or 2 it has started smoking like this.

[sillycar chick]

Yeah I have a BOV, but isn't blue smoke oil? Over fuelling would more likely be black smoke yeah?

Blue smoke is usually a tell-tale sign that the rings are worn. It may not be in this case, but doing wet & dry compression tests are easily done and will at least eliminate the rings as a suspect. It just pays to check and know exactly what is going on before you go messing with things that are ok in your engine. Good Luck, and let us know when you figure out what its!

[Yian]

Not sure about that one,

Plumb back + AFM = air returned between AFM and Compressor = no ecu reading
ATMO + AFM = air returned to atmosphere = no ecu reading

where does the ecu get a signal to run rich?

The ecu doesnt get a signal to dump fuel. BUt with a plumb-back, metered air is being returned into the air tract, whereas with atmo venting BOVs, metered air is being vented. So, it will run rich with an atmo BOV as the ecu still thinks that the air is still in the system and fueling it accordingly....

[mullett]

/\_______/\

What he said

[tooch]

Alrighty, well I removed the BOV and took it for a test run....No difference. So I think I can rule that one out. What I've found so far though:
*No smoke at idle.
*Small amount smoke when I really load the engine up, i.e. 3rd gear up a hill, no boost, i.e. really struggling to get up the hill kinda load.
*Large cloud of smoke ONLY after boosting to around 10PSI...Around 6-7 in 3rd, no cloud that I can see.