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      02-22-2011, 12:14 PM   #9
JAJ
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There's a lot of room for confusion on this point:

- BMW doesn't use direct injection on the M3 engine, so it's not prone to the same carbon buildup problems that plague the Audi and VW engines.

- BMW does use direct injection on the 335i as well as most of the newest generation 6's, V8's and V12's. It is subject to the same problem that Audi has, but BMW seems to have largely dodged the bullet on it. The BMW DI engines are not prone to carbon buildup on the same scale as Audi.

- BMW does have a carbon buildup problem on some of its older engines, but it was carbon forming a blockage in the auxiliary air system that lights off the catalytic converters on a cold start. These air passages in the cylinder head can get blocked, causing the ECU to throw a code and requiring an expensive cleaning. It usually doesn't manifest itself until a number of years have gone by. The S62 engine in the E39 M5 was prone to this issue but I imagine by now that BMW has it solved on a go-forward basis.
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