[astrobmw]

This is our first turbo engine ever (in 40+ yrs of driving) so I may be a bit paranoid. After only 4,000 miles the inside of the right exhaust outlet is covered in black soot while the left outlet is still sparkling clean. Is there anything about the turbo plumbing or exhaust system with AWD that would explain this, or should I be worried about oil leakage on one of the turbos? How much exhaust soot do 2WD 335's show, and is it balanced?

Thanks much!

[low]

I have a 335i and my left exhausts tail pipe is always the "sootier" of the two. I've just attributed this to the fact that cylinders #2 and #6 run hotter than the others based on what is posted on this forum. I'm sure someone else can give you a more techincal explanation...

[hl0m4n]

Originally Posted by low

I have a 335i and my left exhausts tail pipe is always the "sootier" of the two. I've just attributed this to the fact that cylinders #2 and #6 run hotter than the others based on what is posted on this forum. I'm sure someone else can give you a more techincal explanation...

if this "soot" you are speaking of is the black stuff on the inside of the tips it is normal as the car only runs on the left muffler first and later at higher rpms or speed the right muffler opens up.

the unit that controls this is called a...."wow i just blanked out right now lol" something valve. search for nero mod or golf tee which will allow you to disable this valve from doing its job thus running on two mufflers all the time. it will change the sound level a bit too.

[321]

Originally Posted by low

I have a 335i and my left exhausts tail pipe is always the "sootier" of the two. I've just attributed this to the fact that cylinders #2 and #6 run hotter than the others based on what is posted on this forum. I'm sure someone else can give you a more techincal explanation...

[RiXst3r]

exhaust gas flap... disables driver side exhaust for noise reasons, and some say to heat up the cats faster... but its easy to disable. Exhaust will be lower and louder... Some complain of drone after the mod, but only on the e92, because the e90 has an extra exhaust resonator that the e92 does not have.

[normtrum]

Originally Posted by hl0m4n

if this "soot" you are speaking of is the black stuff on the inside of the tips it is normal as the car only runs on the left muffler first and later at higher rpms or speed the right muffler opens up.

the unit that controls this is called a...."wow i just blanked out right now lol" something valve. search for nero mod or golf tee which will allow you to disable this valve from doing its job thus running on two mufflers all the time. it will change the sound level a bit too.

Ha ha...that part just cracked me up That was a good one.

[astrobmw]

Originally Posted by RiXst3r

exhaust gas flap... disables driver side exhaust for noise reasons, and some say to heat up the cats faster...

Thanks very much! I was wondering if it could be something like this but didn't know if the E90 had a crossover pipe. Obviously it does, with a flap downstream on the driver's side - hence our clean left outlet. My wife drives the car 90% of the time so I doubt if the flap opens much. When I get under the car for its first "between dealer service" oil change I will have a look.

[astrobmw]

Originally Posted by astrobmw

I will have a look.

Thanks to the engine management .pdf posted here I discovered that the flap is located just in front of the driver's side outlet. It looks to be vacuum operated since it defaults to open when the engine is not running. Certainly suggests a simple fix (remember to plug the hose, however...)

[hl0m4n]

Originally Posted by normtrum

Ha ha...that part just cracked me up That was a good one.

lol. i don't know i had it in my head and when i was typing i completely blanked out haha

[astrobmw]

Originally Posted by RiXst3r

exhaust gas flap... disables driver side exhaust for noise reasons, and some say to heat up the cats faster...

...and my wife says it is definitely louder with the flap open. Personally I think it will be nice to actually hear the exhaust at something less than WFO and no "we're" not interested in aftermarket systems.

Seems like if it had only been to heat up the cats faster, BMW would have reopened the flap once they were hot, much like they raise the rev limit on an M3 after the oil is up to temp.

This flap is as hokey as the 1-4 skip-shift on our '89 ZF 6-speed manual, not something I expected on the world's best sports sedan.