My E90 335i is unpredictable. It has randomly failed in the following ways, only to correct itself upon restart: Loud buzzing from the speakers when I opened the rear door (engine not running) Misfire at speed (coil or spark plug was to blame but nothing was replaced and it hasn't occurred again) Wild throttle modulation on idle (without me touching the gas peddle). This occurred this morning and was accompanied by a delta sign with an arrow encircling it. Vent closure regardless of fan speed or vent setting Airconditioner compressor wouldn't engage (twice) The revving of the engine today and the coil failure upset me the most. I feel like I'm driving a Microsoft computer since I have to reboot it so often. This is an '09 with 25K miles.
Some of that seems just weird... My thought process would be this... What do all of these items have in common? Figure that out, and you will be on your way to resolving the issue, IMO. I wonder....Possibly a floating electrical grounding issue? Just a thought... Good luck!
Best guess: Have the voltage regulator output checked and perhaps have the battery load-tested. All of those things are computer-controlled and computers detest unstable DC power sources. If your electrical system isn't putting out clean DC power a lot of things are going to act weird in unpredictable ways.
I haven't taken it in yet to find the low voltage issue. I have an appointment on November 8th for a couple other things (30,000 mile service and airconditioner coolant leak). I'll ask them to dig into it then.
So, I still don't know if it is broken or not... The airconditioner remains fully charged from two months ago, so it was determined that no leak must exist. The rev rev revving that takes place upon start-up was deemed to be a software programming issue. It was suggested that the Dinan software be removed, and the latest revision be installed to the BMW software. The latest revision was already installed this fall just before the Dinan software was installed. The low-voltage suggestion was investigated. There were two low-voltage errors from long ago, probably during the time it sat in the showroom. No other issue was found. Ultimately, nothing was done. This reminds me of numerous trips to the Mercedes dealership; the very reason I switched to BMW. How can my car be simultaneously exhilarating and infuriating? It's like on "Modern Family" when Claire asks the big gay guy, "how can something be so frightening that you can't speak of it, and yet somehow you can't stop talking about it?"
Rev rev rev The fast up and down revving at startup turned out to be a throttle issue. A new one was installed, and no new faults have occurred. I am delighted it wasn't software related. My car's cool cool car status has been returned.
