Not sure if my turbo is going bad

[tsitalon03]

I used the search key, but could'nt come up with a straight answer. Anyway, there are a few things why I think this is so. Every once in a while (3-4 times a day) a small-medium sized puff of blueish smoke will come out the exhaust when I take off from a dead stop. It wouldnt do it this if i was cruising down the highway. The off boost power I have is excellent for daily driving. But when I start to build boost, (1-6 psi) I quickly get knock and have to let off the gas. I did a compression test a few months ago and came out fine. I also have a small boost leak at the tb. The turbo itself has no up/down or side to side shaft play. By no means do I beat on my car. Heres what I think: Bad turbo seals or I need to get a tune. Please give me your opinions !

 

[agentorange313]

Blue smoke is an indication that there is oil in you exhaust system. Oil burns blue. Oil can get into your exhaust system a number of ways. Piston rings can go and leak oil into you combustion chamber. Since you have a turbo it can also be the seals withing the turbo, allowing oil into the hot side of the turbo.

Someone correct me if I am wrong, but large intercoolers and piping, the turbo needs to move more air then usual and this can create a situation where knock will occur. I just reread what I wrote and IDK if it correct. I am looking for the source of where I found this, but I cant, so I cant really support my statement. If anyone knows more just correct me please.


I am really not sure what the problem can be besides the turbo seals.

 

[JusMX141]

If you're seeing smoke when starting out from extended idling (I.E. sitting at a stoplight), it's most likely valve seals.

A failing turbo will generally start to smoke upon deceleration from a hard pull and eventually smoke all of the time.

 

[tsitalon03]

Thanks. A few other people I asked said the same thing. How does a leaky seal cause knock?

 

[JusMX141]

Not directly, but if the seals leak long enough that they allow oil to seep down the exhaust valve stems and burn to the seats and the sealing area of the valve, you risk low compression and improper combustion. Poor combustion could lead to a rich-knock condition.

If you're getting knock at the onset of boost around 2500-3000rpms, chances are your knock sensor is on it's way out. My FWD TSi had a similar issue when I first bought it- the car would max out the knock count on my logger anytime I'd get on it from around 2500-3000rpms. It ended up having a giant boost leak around the outlet of the stock sidemount intercooler, and all of the goo had leaked out of the knock sensor and ran down the back of the engine block....so the knock sensor was basically useless.