Black soot found on driveway right under tailpipes

E90Graphite07 · 08-14-2018, 03:21 PM

Car has nearly 169K miles, starting to have some form of black soot build-up on my driveway, right under each of the exhaust pipes. I have no CEL / DTCs appearing, but I'm noticing a pretty strong fume on start-up and poorer MPGs. Thoughts?

I do know that the dealer did specify I needed a new valve cover (not specifically the VCG). It's the original one. I'm assuming they're right, as I'm also losing oil from time to time. Should I assume replacing the VG and getting say a walnut blast to correct my issues. I haven't really speculated the fuel injectors as I'm not experiencing any misfire nor codes.

Please advise...

nOshi · 08-14-2018, 08:32 PM

My guess would be either o2 sensors or injectors, but I'd lean more to injectors. I've had leaky injectors and no misfire, so something to look into.

Psyphertext · 08-14-2018, 09:34 PM

Do you hve exhaust tips and clean the final few inches of the pipes? If the normal exhaust buildup has not been cleaned and an oil leak has begun, it is completely plausible to have buildup increase without creating a notable cloud. I have 68K on my 09 328i and recently cleaned the exhaust tips so I can keep an eye on buildup thanks to threads on the board illustrating the myriad of leak issues with BMW.

A nice trick I learned from a custom guy in Fort Benning years ago. It has served me well for years and a step I take when I pick up a used vehicle.

mweisdorfer · 08-14-2018, 09:51 PM

Quote:

Originally Posted by E90Graphite07

Car has nearly 169K miles, starting to have some form of black soot build-up on my driveway, right under each of the exhaust pipes. I have no CEL / DTCs appearing, but I'm noticing a pretty strong fume on start-up and poorer MPGs. Thoughts?

I do know that the dealer did specify I needed a new valve cover (not specifically the VCG). It's the original one. I'm assuming they're right, as I'm also losing oil from time to time. Should I assume replacing the VG and getting say a walnut blast to correct my issues. I haven't really speculated the fuel injectors as I'm not experiencing any misfire nor codes.

Please advise...

Check out your inlet connections. I had this issue. I had the sensor pop out of the rear inlet and therefore excess air was coming in the inlet causing the black soot.

It could be bad turbo seals

It could be a leaking injector

08-14-2018, 03:21 PM	#1
E90Graphite07 Lieutenant 104 Rep 596 Posts Drives: 07 E90 335i Join Date: Dec 2007 Location: Texas iTrader: (0)	Black soot found on driveway right under tailpipes Car has nearly 169K miles, starting to have some form of black soot build-up on my driveway, right under each of the exhaust pipes. I have no CEL / DTCs appearing, but I'm noticing a pretty strong fume on start-up and poorer MPGs. Thoughts? I do know that the dealer did specify I needed a new valve cover (not specifically the VCG). It's the original one. I'm assuming they're right, as I'm also losing oil from time to time. Should I assume replacing the VG and getting say a walnut blast to correct my issues. I haven't really speculated the fuel injectors as I'm not experiencing any misfire nor codes. Please advise... __________________ 2007 BMW 335i, 2014 Audi A4, 2016 Acura MDX Join us on Facebook: E90Post - Houston Houston BMW DIY Services
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08-14-2018, 08:32 PM	#2
nOshi Second Lieutenant 22 Rep 251 Posts Drives: TiAg E90 335i Join Date: Apr 2011 Location: Central FL iTrader: (4)	My guess would be either o2 sensors or injectors, but I'd lean more to injectors. I've had leaky injectors and no misfire, so something to look into.
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08-14-2018, 09:34 PM	#3
Psyphertext Private 7 Rep 76 Posts Drives: 09 328i Join Date: Aug 2018 Location: Mo iTrader: (0)	Do you hve exhaust tips and clean the final few inches of the pipes? If the normal exhaust buildup has not been cleaned and an oil leak has begun, it is completely plausible to have buildup increase without creating a notable cloud. I have 68K on my 09 328i and recently cleaned the exhaust tips so I can keep an eye on buildup thanks to threads on the board illustrating the myriad of leak issues with BMW. A nice trick I learned from a custom guy in Fort Benning years ago. It has served me well for years and a step I take when I pick up a used vehicle. __________________ if you didn't have fun, it wasn't difficult enough.
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