[Heck1]

I have a 2021 M340i with 46k miles and the car recently developed this smoking issue only happens in heavy traffic or coming to a stop light on occasion. This does not occur every time and the car is completely fine under spirted driving with no smoke under acceleration or deceleration. Also there is 0 smoke at idle or upon startup. Car is Femto unlocked running MHD e40 tune with a catless downpipe for the past 6k miles. I installed a pcv catch can in hopes if it was a pcv related issue like the gen 1 b58 cars experienced. Catch can caught nothing and the issue is still apparent. My only other guess is that the turbo is starting to go? Oil consumption is quite bad now getting about 300-500 miles per qt of engine oil.

Video: https://vimeo.com/920783750

[hayko_M340]

Originally Posted by Heck1

I have a 2021 M340i with 46k miles and the car recently developed this smoking issue only happens in heavy traffic or coming to a stop light on occasion. This does not occur every time and the car is completely fine under spirted driving with no smoke under acceleration or deceleration. Also there is 0 smoke at idle or upon startup. Car is Femto unlocked running MHD e40 tune with a catless downpipe for the past 6k miles. I installed a pcv catch can in hopes if it was a pcv related issue like the gen 1 b58 cars experienced. Catch can caught nothing and the issue is still apparent. My only other guess is that the turbo is starting to go? Oil consumption is quite bad now getting about 300-500 miles per qt of engine oil.

Video: https://vimeo.com/920783750

Mine has been doing this for a while now, probably since a year into ownership. I am also running a E40 map, but it does it regardless of tune or fuel used. Yours is significantly worse than mine, I go through about half a quart or 3/4 of a quart between oil changes 5-7K Miles. Just surpassed 52K miles, it's either the PCV system or turbo can't see it being anything else. On the Gen 2's the Valve Cover needs replacement if the PCV goes which is inevitable with so much added crankcase pressure being tuned, or the turbo is on it's way out which is a reason to go bigger

[Heck1]

Originally Posted by hayko_M340

Mine has been doing this for a while now, probably since a year into ownership. I am also running a E40 map, but it does it regardless of tune or fuel used. Yours is significantly worse than mine, I go through about half a quart or 3/4 of a quart between oil changes 5-7K Miles. Just surpassed 52K miles, it's either the PCV system or turbo can't see it being anything else. On the Gen 2's the Valve Cover needs replacement if the PCV goes which is inevitable with so much added crankcase pressure being tuned, or the turbo is on it's way out which is a reason to go bigger

Upon farther research, seems I was mis-informed and bought a crank case vent catch can. Also due to a failed o-ring on the actual pcv inlet to the block, the whole side of the block is covered in oil, truly showing how much oil is just being dumped into the turbo. No one sells a proper pcv catch can system for our cars, but they do the supra. I'm going to fabricate my own and will report back.

The only real fix would to install head pins blocking off the pcv passage ways in the head and installing Visconti's Gen 2 upgraded valve cover that deletes the pcv system. A proper pcv catch can will work also.

But I'm almost certain this will fix the smoking issue we are all facing.

[Peter S M340i]

So I just did all of that and was about to update my post. I did the pins and replaced my valve cover and it still smoked. I'm running upper and lower catch cans. Initially my DAW turbo was completely dry. After it smoked again, I removed the turbo immediately to go back to stock. Upon a closer look and because it was removed even after just driving it. I could see the oil behind the turbine. My issue the whole time was the turbo. TBH after all of this I recommend driving the car till it smokes. Go back home immediately and remove the turbo to see if you can see the oil like mine.

If you are lucky you can remove the downpipe and see the oil. But initially I could not, I let it cool down too much and by then the oil had dried up. That is why I pinned and replaced the VC. Luckily they are mods I would have eventually done. Just not in the order I wanted to do them. Best of luck!

[Fahad0161]

Originally Posted by Heck1

Upon farther research, seems I was mis-informed and bought a crank case vent catch can. Also due to a failed o-ring on the actual pcv inlet to the block, the whole side of the block is covered in oil, truly showing how much oil is just being dumped into the turbo. No one sells a proper pcv catch can system for our cars, but they do the supra. I'm going to fabricate my own and will report back.

The only real fix would to install head pins blocking off the pcv passage ways in the head and installing Visconti's Gen 2 upgraded valve cover that deletes the pcv system. A proper pcv catch can will work also.

But I'm almost certain this will fix the smoking issue we are all facing.

Hey man! Did you manage to fix this? My cars been parked up for a month! Because I can't seem to workout what the issue is 😢

[Heck1]

Originally Posted by Fahad0161

Hey man! Did you manage to fix this? My cars been parked up for a month! Because I can't seem to workout what the issue is 😢

I installed the head pins and did a custom dual catch can setup, I'm testing it currently, so far seems good.

[MAKH 5]

This was happening to me frequently. Driving hard, normal, after a cold start and when the car was up to operating temps. Didn’t matter. Burning smell and smoke would come from the exhaust. Sometime after that, my oil pressure started going crazy and the car developed a whine. Replaced the oil pump and hasn’t occurred since.

Edit: Should have watched the video first. I only saw the smoke after coming to a complete stop. Never while the car was moving.