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Old 10-04-2012, 08:48 AM
Officially Welcomed to the 'Fest
Location: San Francisco
Join Date: Aug 2009
Posts: 10,410
Mein Auto: 2009 E93 N54
Originally Posted by jwhallman View Post
Even if one Believes that all DI engines suffer from carbon (they don't) it is BMW who touts their 100% free maintenance. Look at the TV ads that proclaim even your wipers are covered free of charge. But that is a big fat lie because their lousy engineering means your valves should be cleaned by 50k miles.

No they don't. Anecdotally related to PCV valve blow-by [crankcase oil] without fuel to wash it off the valves, coking is usually related to high rpm operation. Meth injection having little or no effect re: coking. The final, totally effective solution is to route PCV valve exhaust to atmosphere.

But -- tut tut tut! -- that's an emissions violation carrying somewhat of a penalty.

A quick SEARCH will reveal details of BMW's cyclonic separation, catch-can solutions, and many pics of coked valves. Will also route you to solutions such as this DIY - click on the PDF in Post #1. Dealers generally charge $600 for the walnut shell treatment - BMW's developed tools specifically for the task; I've ordered them in anticipation of the issue. Yup, I like the certainty of a good DIY.

There's been mention of a cure involving fuel and valve timing, and there are theories about fuel dilution and lubricant volatility, but the little I've read offers no tech specs. GM reputed to have have an effective solution.

Call me nuts, but a condensing catch-can would seem to be an excellent thing.

How 'boutcha, 60k+ mi N54 pilots.....have you had the problem?

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Last edited by CALWATERBOY; 10-04-2012 at 09:16 AM.
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