Exhaust soot.

The first few times I drove my new 335i, I noticed a lot of black soot on the right exhaust. It's now been sixteen days since picking it up, and the odometer is around 450 miles. The funny thing is, the last two times I've driven the car there was no black soot on the pipe when I got home. I'm wondering if this is something that usually occurs only when the engine is brand new and if it decreases with time and miles.

I'm not unhappy about it. Now, if I could ever get a chance to wash it and spray the wheels with that Armour All Wheel Protectant, that would help with the brake dust issue. If it's not one thing, it's another. Life is hard when you're a perfectionist.

Anyone? Anyone? Bueller?

normal and doesnt decrease. there's more soot on the right pipe because the exhaust has a valve in the left pipe thats closed at low rpm to reduce noise.

Thanks Orient.

I'm still wondering why the black residue has decreased so much the past couple of days.

Originally Posted by mbroadway

I'm still wondering why the black residue has decreased so much the past couple of days.

It's a bit variable depending on how you drove recently: Short trip, highway cruise, how much part throttle vs. full throttle, etc., etc.

Don't worry, it'll be back.

& temperature, temperature range, humidity, et. al.....

Originally Posted by Orient330iNYC

normal and doesnt decrease. there's more soot on the right pipe because the exhaust has a valve in the left pipe thats closed at low rpm to reduce noise.

I think this is partially correct. I believe the valve directs the exhaust to the right tail pipe until the catalytic converters warm up. Once warm, the exhaust is directed to both pipes regardless of rpm.

Originally Posted by Eights-n-Aces

I think this is partially correct. I believe the valve directs the exhaust to the right tail pipe until the catalytic converters warm up. Once warm, the exhaust is directed to both pipes regardless of rpm.

nope, has nothing to do with the catalytic converters-- my performance exhaust has no valve. if it has any effect on emissions, bmw would not be able to sell it without the flap. it will actively close to reduce noise.

Main reason:

"In order to enhance the exhaust note emanating from the tailpipe(s), BMW has arranged a thermistor switched, electrically controlled, vacuum operated butterfly valve to close off the tailpipe on the driver's side while the engine warms up. This results in a more pleasant exhaust note when you are first pulling out of your neighborhood." Gig103 02-05-2008, 10:19 AM

Originally Posted by Zeichen311

It's a bit variable depending on how you drove recently: Short trip, highway cruise, how much part throttle vs. full throttle, etc., etc.

Don't worry, it'll be back.

+1

- Mike

I notice it on my new 528xi drivers side tail pipe today for the first time. Must say was a bit worried, its been driven 650 miles. if it is a rich fuel mix, why should new cars have such inefficient setting?

Originally Posted by Thumperx

Main reason:

"In order to enhance the exhaust note emanating from the tailpipe(s), BMW has arranged a thermistor switched, electrically controlled, vacuum operated butterfly valve to close off the tailpipe on the driver's side while the engine warms up. This results in a more pleasant exhaust note when you are first pulling out of your neighborhood." Gig103 02-05-2008, 10:19 AM

This, exactly. Does not related to RPM. Once warm, both stay open.

Originally Posted by mbroadway

The first few times I drove my new 335i, I noticed a lot of black soot on the right exhaust. It's now been sixteen days since picking it up, and the odometer is around 450 miles. The funny thing is, the last two times I've driven the car there was no black soot on the pipe when I got home. I'm wondering if this is something that usually occurs only when the engine is brand new and if it decreases with time and miles.

It might be due to the fact that your piston rings are still seating, hance the need for a good break in period.

I'm not sure about the cause, but after 6,000 miles, I traded the car in on a 2012 Mustang GT with 412hp and a 6-speed manual. I freaking LOVE this car. Not saying anything negative about BMW, but I really like the Mustang a lot better. I take every opportunity to drive it. Fast. For some reason, both of my tail pipes are clean as a whistle inside, even after 5,500 miles. So, my problem has been solved.

Originally Posted by mbroadway

I'm not sure about the cause, but after 6,000 miles, I traded the car in on a 2012 Mustang GT with 412hp and a 6-speed manual. I freaking LOVE this car. Not saying anything negative about BMW, but I really like the Mustang a lot better. I take every opportunity to drive it. Fast. For some reason, both of my tail pipes are clean as a whistle inside, even after 5,500 miles. So, my problem has been solved.

Do you need a link to the Mustang forum? I took a peek...it's overrun with chewing tobacco and beef jerky ads...but you've made your bed and have to sleep in it.

Thanks for the offer, but I already have a link to several Mustang forums. Funny, I didn't see any beef jerky or chewing tobacco ads. LOL.