[n54Newb]

car Does not smoke on accel or decel or idle at operating temp. I noticed it only smokes after braking really hard or slamming the brakes. never any smoke on regular decel without brakes or in any situation. the smoke smells awful any clue to what it might be?

[Cascade253]

I had something similar, turned out to be water in the mufflers running back up to the hot cats. Take a 1/8" drill bit and make a hole in the lowest part of each muffler. You will be surprised at how much water will come out.

[n54Newb]

YES!! i believe my mufflers are full of water.... i drove the car for 2 hrs no smoke at all and did a couple wots when i had space that wont force me to heavy brake. and when i got home after the drive im able to touch the bottom of my mufflers barehand and it felt cold make sense it would stay cold if there's lots of water pooling.

[Cascade253]

I genuinely surprised there's no seep holes in the mufflers from the factory. This is something I've seen on almost all the other vehicles I've had.

[n54Newb]

question i put a small hole thru my mufflers and the left side had like a whole water bottle in it if not more. the right side dripped black watery soot for a while too. Before i would drive for hrs and i would touch the exhaust mufflers it would be cold. now after making a hole and getting some of the water out. the muffler isnt cold but its still touchable and part of is still cold i have bought a borescope and tried looking at my turbo lines. and my rear turbo feed line is leaking and i can trace the oil down to the bottom of my catless downpipes from the outside. would that cause smoke at all.... now on cold starts i get no smoke i drive for 10 secs and stop i get small puff of smoke. but after 2-3 mins of driving no smoke at all. i still get smoke when i brake heavy and lets say i got the car to operating temp and i shut it off for 1 hr or 2 and i start it first couple mins of driving boosting idling anything with car on it would smoke but after the car is slightly warmed up no smoke anything.im guessing there bunch of gunk build up thats burning off or maybe because im missing my secondary o2s...... not sure i recall with my previous n52 e90 i wouldnt be able to touch the muffler if it ran for more then 5 mins and i accidently burnt my self on it years ago. by touching it for split second. doesnt seem like my current muffler is getting any where near as hot

my parking spot is on a incline where the front of my car is lower then the back.

[n54Newb]

bump

[Podunk]

residual water in the pipes, condensation from when it cools off and gets cold overnight, there will always be water vapor initially, because of the condensation effect, and a byproducts of burning hydro carbon chains with catalytic converters reactive materials is, WATER VAPOR. if you're not experiencing any driveability issues, i wouldn't worry about it too much.

[lookalikehuuh]

I had some foul smells when coming to an abrupt stop at one point, turns out it was the backside of my valve cover gasket not sitting correctly. Somehow the hard stops made oil drip down and hit the cats/exhaust and man it stunk like hell.

[n54Newb]

update it might be my valve stems leaking but I'm not entirely sure if the symptoms match. the car on cold starts doesn't smoke in idle until i start driving and first 10 second i get a puff of smoke.... the car at operating temp doesnt smoke at all idle decel-accel.but if i park my car for around a hr after it reached operating temp and i start the engine i get alot of smoke for first 5 mins of driving on decel and accel but after that i can drive for hrs without any smoke. would this be leaky valve stems?
200k miles on the car