[rjd_F30]

Hey all,

Looking for some insight on an issue I'm having with my 335i (N55 PWG). I've been having a problem lately where the car will emit a pretty startling amount of white smoke from the exhaust while parked and idling after hard driving. Not losing coolant and the oil looks perfectly fine, so I don't think it's a head gasket or anything water related. It doesn't smoke on startup, while driving, or while idling after mild/normal driving; only while idling after hard pulls and spirited driving. The smoke also has a burnt smell to it... not sweet like coolant, but I guess like burning oil (it's catless but it smells more burnt than the normal catless smell). I had a friend follow me while doing some pulls and he said there was no smoke at all coming from the exhaust. And finally, the car runs absolutely great, still pulls hard and smoothly. I'm taking it in to the shop tomorrow for diagnosis, but just wanted to get your guys' thoughts so I can maybe know what to expect. I'm thinking a turbo seal or PCV, but curious to hear what you all think.

Any and all input is appreciated! Thank you!

Mods are FMIC, DP, CP, Catback, BM3 S2 93.

[frchdragon]

Blue smoke is burning oil.
White smoke is burning coolant / water.

If our turbos are watercooled, could be the problem.

[rjd_F30]

Originally Posted by frchdragon

Blue smoke is burning oil.
White smoke is burning coolant / water.

If our turbos are watercooled, could be the problem.

Doesn't smell anything like burning coolant though, otherwise I'd say it's coolant-related too. I appreciate the input though.

[n55david]

it's usually just moisture fyi

[rjd_F30]

Originally Posted by Phantom10R

it's usually just moisture fyi

It's a lot more smoke than what I think would be reasonable for moisture/condensation. The first time it did it it was a plume of thick white smoke. If you couldn't see the car you would've thought there was a fire.

[thejeremyman9]

You said no coolant loss... any oil consumption?

If its PCV-related, you will have a lot of oil in your intake system between the turbo inlet and the TB. You can pull off any piece to check, the top of the CP is probably the easiest.

If its turbo oil seal - if its cold side, you would have the same as above. If its hot side, you would be burning all that oil in the exhaust, which would be most noticeable in the DP but probably also with extra buildup on exhaust tips if you are catless.

[rjd_F30]

Originally Posted by thejeremyman9

You said no coolant loss... any oil consumption?

If its PCV-related, you will have a lot of oil in your intake system between the turbo inlet and the TB. You can pull off any piece to check, the top of the CP is probably the easiest.

If its turbo oil seal - if its cold side, you would have the same as above. If its hot side, you would be burning all that oil in the exhaust, which would be most noticeable in the DP but probably also with extra buildup on exhaust tips if you are catless.

Super helpful, thank you. I just dropped the car off so I won't have a chance to check for oil in the intake. But I didn't get any low oil lights, and when I measured using the iDrive, my oil level was about the same after maybe 100 miles of driving. So no significant oil loss, at least I don't think.

Sounds like you don't suspect something internal or too terrible which is nice. And if the turbo needs rebuilt that just gives me an excuse to upgrade it.

[thejeremyman9]

Originally Posted by rjd_F30

Super helpful, thank you. I just dropped the car off so I won't have a chance to check for oil in the intake. But I didn't get any low oil lights, and when I measured using the iDrive, my oil level was about the same after maybe 100 miles of driving. So no significant oil loss, at least I don't think.

Sounds like you don't suspect something internal or too terrible which is nice. And if the turbo needs rebuilt that just gives me an excuse to upgrade it.

Gotcha. PCV (aka CCV) hose from VC dumps right into the turbo inlet. If they just pull the intake they should be able to see/feel if there in a bunch of blowby going into the intake system. From that point it has to travel all the way through turbo, TIC, IC, CP, past the TB and through the intake manifold to make it into the engine. Given that your problem is at idle after the hard pull, i would say that's pretty unlikely. But checking for oil in the turbo inlet and then in the top of the CP is one way to get an indication of how much blowby you have.

[rjd_F30]

Originally Posted by thejeremyman9

Gotcha. PCV (aka CCV) hose from VC dumps right into the turbo inlet. If they just pull the intake they should be able to see/feel if there in a bunch of blowby going into the intake system. From that point it has to travel all the way through turbo, TIC, IC, CP, past the TB and through the intake manifold to make it into the engine. Given that your problem is at idle after the hard pull, i would say that's pretty unlikely. But checking for oil in the turbo inlet and then in the top of the CP is one way to get an indication of how much blowby you have.

Also, very helpful, I really appreciate your input! I talked to them today and they couldn't replicate the issue (I'm assuming because they didn't romp on it as hard as I would because it's a customer car), but I'll give them a heads up on this as something to take a look at.

[frchdragon]

Originally Posted by Phantom10R

it's usually just moisture fyi

Makes sense if it is early in the drive or super cold weather, but if after a long drive you still have white smoke, all moisture is gone.

[rjd_F30]

Update: shop couldn't reproduce the issue, they did a thorough check (looked at plugs, for oil in intake, all fluids etc.) and saw no problems. Makes me think even more that it's turbo related. But for now I'm just gonna keep driving the car and see if it stops/gets worse and go from there.

Will update again if anything comes of it. Thanks everyone for your input.

[thejeremyman9]

Originally Posted by rjd_F30

Update: shop couldn't reproduce the issue, they did a thorough check (looked at plugs, for oil in intake, all fluids etc.) and saw no problems. Makes me think even more that it's turbo related. But for now I'm just gonna keep driving the car and see if it stops/gets worse and go from there.

Will update again if anything comes of it. Thanks everyone for your input.

Do you have a gopro you can mount on the back of the car and/or have someone drive behind you and take a video to capture it happening?

[SlowF30]

My guess would be turbo seal on the hotside. Let the car sit over night and pull the DP. If you feel a pool of oil by the turbine wheel its the turbo.

[XutvJet]

Likely a valve guide/seal or turbo seal. It could a weird PCV issue too. I know some B58s have had smoking issues when at extended idles, the issue a failed PCV component in the valve cover I believe. Perhaps the N55 can have a similar issue?

I'd get a compression test and rule out the really expensive stuff.

Something isn't right and it's likely somewhat serious or very serious. Sorry to be the bearer of bad news.

[rjd_F30]

Originally Posted by thejeremyman9

Do you have a gopro you can mount on the back of the car and/or have someone drive behind you and take a video to capture it happening?

Only happens at idle, so I don't think that would be of much use. I did have a friend follow me around for a few miles after it did smoke at idle to make sure it wasn't occurring while driving, and he said it didn't smoke one bit while driving.

[rjd_F30]

Originally Posted by SlowF30

My guess would be turbo seal on the hotside. Let the car sit over night and pull the DP. If you feel a pool of oil by the turbine wheel its the turbo.

That's what I'm thinking at this point too.

Originally Posted by XutvJet

Likely a valve guide/seal or turbo seal. It could a weird PCV issue too. I know some B58s have had smoking issues when at extended idles, the issue a failed PCV component in the valve cover I believe. Perhaps the N55 can have a similar issue?

I'd get a compression test and rule out the really expensive stuff.

Something isn't right and it's likely somewhat serious or very serious. Sorry to be the bearer of bad news.

I'm kind of hoping it's a turbo thing to be honest. I've been on the fence about upgrading and this would be a good excuse to do it. Valve seals wouldn't be as fun however lol. But I imagine if I had a valve seal issue, I'd have smoke more frequently than just the very specific instances in which it happens now, and the car would probably run like crap, right? It runs great, sounds great, pulls strong and all that, just this darn smoke at idle after pulls... that's the only symptom.

[thejeremyman9]

Is it reproduceable every time? If it is, can't you just reproduce it for the shop by doing some hard pulls and then pull right into the shop and have them ready to look at it?

[rjd_F30]

Originally Posted by thejeremyman9

Is it reproduceable every time? If it is, can't you just reproduce it for the shop by doing some hard pulls and then pull right into the shop and have them ready to look at it?

It was for a few days, and now it's not doing it anymore. I did some hard pulls last night and got no smoke at all. Really odd... I'm a bit confused at this point.

[f82jay]

Did you ever fix the issue currently having the exact problem I think it’s my turbo seal being worn

[rjd_F30]

Originally Posted by f82jay

Did you ever fix the issue currently having the exact problem I think it’s my turbo seal being worn

Nope. It doesn't really do this anymore and I did nothing to fix it.

Car runs great 3 years and 25k miles later.

[f82jay]

Originally Posted by rjd_F30

Nope. It doesn't really do this anymore and I did nothing to fix it.

Car runs great 3 years and 25k miles later.

Damn now I’m curious because my car runs nice and smooth but whenever I do hard pulls I get a burnt smell and not a crazy amount of smoke but enough to raise concern I’m also catless but the smell is completely different and like I told myself if it’s the turbo seal I’m just gonna upgrade and go single but someone said it could be a bad injector but the smoke doesn’t happen while idle or on start up only after over boosting