cadillacby

I have 2008 533xi. here is the story: one day i couldn't start the car in cold weather. It was cranking 3 times and stops every time i tried. Checked battery- it was showing 11.5V. I took battery home and charged it. Next day installed battery and started the car- car started rough , was shaking and i got 2 cylinders misfires. Swapped coils and spark plugs- no difference- same cylinders misfires. Checked DME- had fried mosfet on cylinder 3. Bought MSD81 programmed and installed. Started the car- cylinder 3 misfire again. Replaced all spark plugs. Now i have no misfires, but car slow to accelerate and vibrating (much less than was before but still). Now i have code P2c77. At the moment it looks like everything i fix something else comes up. Should i go forward and replace HOS2 and hope it will fix loss of power and vibrating or i'm missing something else?

twh

Why would you jump to the conclusion to replace the MSD81?

cadillacby

i did voltmeter test on mosfets. One of them was fried.

seanjordan20

I've never seen anyone replace the whole DME for MOSFETs but that is a way to correct the issue. There's companies that replaces them. It seems like it wasn't your issue since replacing the plugs got rid of the misfire. I would also check the injectors because that very well can be an issue.