Please Help!!! With Bmw Engine
I have a 2000 BMW 528i and recently started having issues with the car. I've taken it 2 times to an authorized BMW service shop (Herb chambers BMW Boston) and spent about $4500 fixing it as it is out of warranty. Almost all of the problems have been fixed except one! My engine keeps stalling out!!! This is during the wintertime in Boston so it's very cold. I thought perhaps the cold snapped the battery so I changed to a brand new battery. But the very next day, the car stalled out again! I leave the car running in the morning so the engine would warm up but after about 10 minutes of running, the rpm dips so low (about 400) that the car just shuts off. And sometimes I would sit in the car and just watch the rpm go up and down up and down. It would rev very low at like 400 and suddenly correct itself and jump up to about 1000 rpm and comes back down again. The car would do this about once every minute and finally stall out.
Mind you I've taken the car back to the dealership 2X and every time they diagnose it they said they couldn’t find anything pertaining to why the car would just shut off. Last time I replaced a coolant sensor and idle air control valve, which had nothing to do with the car stalling.
My car has low mileage, 2000 car and only 76000 miles. I don't drive that often and not rigorously. I'm just so worried about my car and not to mention all the money I spent fixing it within these two months. The BMW service people said there’s nothing wrong with the starter or alternator. They keep telling me the same things every time: check out your battery, change fuel grade, etc. But everything they told me, I did, and nothing helps. My car's sporadic revving and stalling just got me scratching my head. I even went to Auto Zone and had them check out the starter and alternator and the new battery I replaced. They said everything’s fine.
Nothing and no one can tell me what is going on with the stalling. If you are reading this and you have any idea about what's going on PLEASE HELP me understand. It’s not the starter, not the alternator, and not the battery. So what else can it be? What else should I look into to stop my car from stalling out in the wintertime or am I doomed every winter from now on? And are those BMW service technicians really just full of it???