Originally Posted by Thud
The prevailing theory I've been reading in other threads is that if you have the EGR recall service done while the car still has low mileage, then you're much less likely to experience carbon buildup-related problems later on.
Good thought. I want to follow it for a minute based on my evidence because I'm not sure it supports a linked relationship between carbon, injector failures and DDE failure.
My EGR recall was done after injector failures started, and injector failures continued. Same with my carbon cleaning. The evidence would support carbon build-up happening largely before the EGR recall, and could support carbon build-up being reduced by the EGR recall; but my injector failures seem to be an unrelated issue based on their persistence throughout.
BMW's theory is that my DDE failed, causing it to mis-fire the injectors, which caused rough idle and the DDE mis-diagnosing injector failures. Is it possible that something about the original EGR valve design could cause the DDE to fail? I'm sure you guys understand common rail diesels better than I do, but understanding electronics this would surprise me.
The one thing that I can definitely say about my EGR/SCR recall is that DEF use went down. I was filling the DEF tank every 4,000-6,000 miles before the recall. After recall, I make it to expected service intervals.
I really don't know how prevalent injector failures are but it sounds like a number of us are having them. Failures could be related to the low-lubricating nature of the US ULSD fuel; or in fact related to failure-prone DDEs; or in fact related to something else that is causing injector or DDE failures. Either way, the evidence suggests there is more than the EGR issue at play here.