So this morning, I head out to play tennis, and when I come back from the game to the parking lot, I see this - 330ci, 135i, & 428i convertibles standing together. But what took me by surprise was the black soot on the 135i and 428i cars. anybody have any ideas why my 2005 330ci has no soot, while these 2 nearly new cars have so much soot?

 

Sorry no idea on the soot. Maybe turbo vs NA??

I just wanted to comment how cool it was to see 3 different BMW verts. Too bad the 428i didn't have it's top down.

 

Usually means the engine is running rich: too much fuel versus the amount of air.

But in all honesty, those don't look too bad. It's kind of normal to have some soot as engines aren't perfectly efficient. But heavy soot is usually a sign of a rich fuel/air mixture. Something might be wrong with the fuel management.

A white, crispy-looking exhaust is the exact opposite: too lean fuel/air, too hot.

 

Yes, in general, black soot means a too-rich mixture, but it could also be in the specific detergent package in the brand of fuel used. And, though I don't know for sure if BMW is one of them, I understand that some automakers set the engine computer in new cars to run rich for a period of time to help guard against possible engine damage during and after break-in.

 

It's the oil that is burned from the turbos. Like my 128 doesn't have that either. I love my bmw, but I wouldn't own a turbo bmw. Since the 128 was the last of the na bmws I guess it's my last one. That 135 may not have to updated injectors either. It looks like the 135 is an older one with the n54.

 

Well typically oil burning produces bluish smoke, but it typically doesn't leave a black sooty residue. If it's burning oil, you'll see smoke.

Rich fuel conditions means not all of the fuel is burning and like the black smoke you see on a candle (because it's not fully combusting) it's the leftover fuel that has only partially combusted. That is soot and that's what accumulates on the tailpipes.

I had the same thing on my normally aspirated Acura RL (no turbo) and it was diagnosed as a rich burn condition.

And, nothing was wrong in my case, but under heavy throttle, it just dumped a lot of fuel based on their stock air/fuel ratio and inevitably some of it doesn't get burned fully. It was Honda's programming more than anything else that caused that condition.

 

This has little to do with a car running rich. It has everything to do with the level an owner cares about the cleanliness of his/her car. The majority of drivers do not care about their tailpipes. You will find most cars out there will have dirty, black tips- even nearly new cars. I have studied this since the 90's. What makes it worse is most car washes do not wipe off tips. So unless the owner makes a concerted effort, they never get touched. There's also a new trend today of making all trim on cars black- rims, emblems, and now tailpipes. So the natural stain is sadly becoming the look.

In the world of auto detailing, there are three tricks in making a car look new: Clean rims and wheel wells, clean tailpipe tips, and tire dressing.

 

I remember laughing out loud when I read in my MB handbook that they recommend using silver polish on the tail pipes :roll eyes: just a towel wipe down will do

 

I have never cleaned my tailpipes. That said, my Lexus IS has pretty dark soot, MB a very light coat, and my earlier Mazda6 v6 had no tail soot.

 

My initial feeling was also that it's attributed to the level of care given to the cars. The two newer Bimmers are likely given the car wash treatment whereas the beautiful E46 is hand washed with love.

I only take my car to the car wash during the winter months and there's no question that a car wash isn't going to get the little areas where dirt gets stuck, the tailpipes, and most of the wheels. While I know that in the grand scheme of things all this doesn't really matter, I'm a car enthusiast so I enjoy hand washing cars and obsessing over every little detail. It's a hobby.

 

Guys, cars with direct injection are prone to produce plenty of exhaust soot. This is very normal.

 

This. When I had my aftermarket Tanabe exhaust, I would clean that at least once every 1 week after a wash to keep it nice and polished. I liked the way it glistened when it was cleaned. I was thinking that may be the case here.