My car is now due for its oil service and so I thought this might be a good time to seek some professional input on the error code P3263. I use a BMW dealership because they've treated me well in the past and my hope is that they know as much, if not more, than anyone else. Unfortunately to my surprise they informed me that the OBD fault codes obtained from my ELM device are meaningless to them! The 'official' BMW diagnostic tools access another set of codes! So I have two choices. To put my faith in the dealership to efficiently solve the problem or continue investigation. Having read several horror stories of people spending hundreds of pounds at garages and the same fault re occurring soon afterwards I favour some further investigation.
To this end I've been studying more about MAF meters, EGR valves, turbo boost control and how that relates to volumetric efficiencies and fuel metering! The tool I've been using is my bluetooth ELM327 interface and Torque app on my Samsung phone. It has allowed me to log these parameters to a spreadsheet in order to try and analyse what may or may not be happening. The results are interesting but it's still difficult to draw a conclusion without the benefit of a set of results for a 'healthy' engine. One thing it is easy to see is that the EGR valve is working following it's de-coke. Disconnecting the vacuum pipe that opens and closes the EGR causes the results to change dramatically. It also causes black smoke from the exhaust when revved. A common sight from a diesel but something I guess has more than one reason.
More later as I look more closely at the figures or take the plunge and buy a new MAF meter.
