[Armyflyguy]

Very long post warning- but worth it if you've been trying to figure out your white smoking issue.

First a back story to paint a complete picture..
I'm a relatively new BMW owner as I purchased my 2010 e92 335i about 3 months ago. It was bone stock and only had 62k on the odometer. I'm a helicopter mechanic in the Army and have been a DSM guy/owner(4g63) for the last 20 years. So I'm far from turbo illiterate.

After the purchase of the e92, I researched and discovered all of the things people normally have issues with. I also had these issues on my car. Valve cover leak, oil pan gasket leak, coolant hose brittleness, vacuum hose brittleness, water pump, etc etc. I wanted to increase the power, but I needed to address those issues first. I dropped several grand to get the car where it needed to be before adding FBOs and doing an mhd flash. The parts finally arrive and I go to work installing everything.
Before putting the car on a lift to dive in, I had driven the car approximately 2.5k with zero white smoke issues from the exhaust.

Keep in mind I have all of the latest revision injectors, hpfp, etc...everything is up to date.

I finish doing preventative maintenance and proceed with the FBOs- dual cone filters, silicone intake pipes, upgraded turbo outlets, high density fmic, charge pipe, catless DPs, vent to atmosphere tial BOV....and an MHD 2 flash.

A couple of days after doing the flash I notice a little bit of smoke from my exhaust. I instantly think "f!@$, I just blew my turbo seals from the flash...perfect!" But it was just a slight amount and I wasn't able to discern what color the smoke really was. I didn't see this smoke again until a couple of days later when I pulled in to convenience store and a tailwind blew a sizeable cloud of white smoke over my car. It was clearly white smoke. This made me think twice about my turbo seals being blown as it wasn't the right color. Just like others with "smoke" issues, it was not very repeatable an it always seemed very random.
My coolant looked great with no sludge, and most importantly, the smoke I had didn't smell sweet at all like burning coolant normally does. The smoke just smelled like really foul smelling bad exhaust. This threw me for a loop and never sat right with me as it should absolutely smell sweet if it has anything to do with coolant.

So I do research. I never found anyone who truly solved the issue.

Some posts claim leaky injectors. This never made sense as that doesn't produce white smoke...even less so if the car has been running. And I have new index 12 injectors.

I came across some threads about the pcv system. I ended up buying a high side catch can and an RB pcv valve. The smoking issue continued. I then bought a low side catch can and the RB external low side setup...but still smoking.

At this point I've already disconnected the DPs and found zero seal leaking issues. I had given up trying to find the issue...

And then today I 100% believe I have found the source of the white "smoke"....

I turned off traction/stability control and launched the car. I see in the rear view mirror what appears to be tire marks. As I circle back around I see that it's not tire marks on the road, but what looks to be liquid that has come out of my exhaust and it matched the distance between each exhaust outlet. It had also evaporated pretty well which would not indicate any coolant as coolant does not evaporate nearly as quick as water. THIS WAS A LIGHTBULB MOMENT. I had taken my time to get back to where I had initially launched the car so much of the liquid that came out was gone, but I snapped a picture anyways.
I decided to launch the car again to try and repeat what happened and then circle back quickly to observe what was left behind. There was a sizeable amount of liquid again with same footprint of my exhaust tips that had not yet evaporated. This led me to one conclusion.. THE WHITE SMOKE IS SIMPLY CONDENSATION IN THE EXHAUST PIPES just being boiled off(a lot of it) and mixing with the exhaust-that's why it smells so bad.

Here are the factors leading me to believe it is just condensation.
-No sweet smell=not coolant
-"smoke" is white, not dark grey or black=not oil
-No oil leakage symptoms on turbo hot sides=not turbo seals
-high/low side catch cans installed with RB pcv valve and external pcv setup had zero effect on "smoking", and smoke from this should still be dark grey or black=not the pcv system
-injectors. My injectors are index 12 with no leaking, and leaky injectors still would not make white smoke while driving=not injectors
-valve cover was replaced with gasket and is crack free= not a leaky valve cover

Nearly every post I've read, to include my own experience, has "smoking" issues after catless DP install and on deceleration. With with my liquid shooting out of my exhaust I've come to the conclusion that our engine/exhaust produces a large amount of pooling condensation buildup within the exhaust pipes. Exhaust pipes are naturally hotter towards the turbos and cooler towards the exits in the rear. When people are decelerating, the pooled water flows forward toward the hotter end of the exhaust, causing it to steam off rather quickly and come out of the exhaust pipes. With catalytic converters installed, this is not an issue because there is so much surface area in the honeycomb of the converters that it burns off a ton of that water quickly and immediately, thus we never see it....except for those with catless downpipes and on deceleration.

I'm attaching two pictures I took when I launched the car earlier today. One has very little liquid left on the ground. That is from when I took my time to circle back to where I launched and it's also when I realized the smoking may just be water, so I needed to do a confirmation launch.
The second picture is when I returned quickly to confirm my suspicions that it was just water....that's why there is so much more left on the ground.[IMG]undefined[/IMG]

[Dave92N54]

What's the temperature around you? I'd find it hard to believe that much water is accumulating. Not saying impossible though.

I experienced something very similar when I blew my rear turbo, though as far as I could tell it wasn't leaving liquid on the ground. The turbos even looked dry both times I pulled the downpipes to make sure the smoke wasn't turbos. Once I replaced them, smoking stopped and upon closer inspection of the rear turbo, the exhaust turbine was just a tiny bit wet. The turbos will dry out fairly quickly until it gets bad enough. I went probably 5-6 months with it smoking exactly how you described, erratic, white, and with a strong breeze there would be a good bit more smoke. I bet when it does happen, it's usually when coming to a stop or when just starting to move? I noticed mine would happen most times if I started the car, drove a very short distance (2 minutes?) shut it off, did something, and then started it back up. Then, within the next 5 minutes I would get exactly one puff of smoke out the back.

Oil burning in the exhaust of our cars often shows white, not gray or black. If you have catless downpipes, it will be white with the slightest hue of blue. Gray or black almost always means fuel.

[mweisdorfer]

Nearly every post I've read, to include my own experience, has "smoking" issues after catless DP install and on deceleration.

This is because the cats hide this issue

[N54_e90]

Usually its the turbo, could also possibly be valve seals... when i put some oil saver in my car (for my oil pan gasket and one turbo leak), it solves my smoking issues completely for a few weeks until I believe it wears off, so that's why I'm leaning towards a seal...

[ozi]

Coulndt that water be also from just washing the rear bumper?

[mweisdorfer]

Originally Posted by krazythedon

Usually its the turbo, could also possibly be valve seals... when i put some oil saver in my car (for my oil pan gasket and one turbo leak), it solves my smoking issues completely for a few weeks until I believe it wears off, so that's why I'm leaning towards a seal...

Turbo seals.. unless you get Blue Smoke upon start up. Then it would be the valve stem seals.

[tej98]

I believe I have something similar going on. On warm starts only for about 1 minute or less I will get white smoke that dissipates quickly and has no smell whatsoever. I've been leaning towards drilling a hole in the lowest point of each muffler to allow any water to drain out since that seems like it could be an issue. The car has no symptoms of leaky injectors or oil consumption so I'm not too worried about the other common issues.

[Aode06]

Turbo seals, change the oil and filter add AT 205 from AutoZone,advance auto etc
Along with the new oil and filter. After a few months of driving,the smoke will subside.


Make sure to use oil formulated for the n54 European oil/turbo 7.0 quarts total