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JayPutelis, Shop Foreman/ BMW Master Tech
Category: BMW
Satisfied Customers: 866
Experience:  12 yrs Experience; ASE Master Technician; ASE L1 Certified
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2004 BMW 745Li VIN: WBAGN63464DS48525 274E - DME: misfire

Customer Question

2004 BMW 745Li VIN: WBAGN63464DS48525
274E - DME: misfire detection, cumulative error
2749 - DME: misfire detection, cylinder 2
Vehicle came in misfiring on cylinder #2. I initially replaced the spark plug and ignition coil on that cylinder. Misfire didn't go away so I did a compression test, which showed normal compression. With the vehicle idling I tapped the fuel injector for the #2 cylinder and the engine cleared up and ran smoothly. I then replaced the fuel injector. The vehicle is running better but still misfires on the #2 cylinder on cold starts, but runs and drives smoothly once the engine warms up. It also runs smoothly on warm restarts.
Just misfires on cold starts?
(I've also replaced the crankcase vent valves, checked for vacuum leaks (didn't find any), filled the tank up with premium and some fuel additives, and reset the engine adaptations...)
Submitted: 8 months ago.
Category: BMW
Expert:  JayPutelis replied 8 months ago.
Hi there. Do you still need assistance? If so, can you provide the VIN of the vehicle?.
Thanks, JP
Customer: replied 8 months ago.


Expert:  JayPutelis replied 8 months ago.

Since spark plugs, coils, injectors, compression, etc. is ok. The problem likely lies in the intermediate levers for the valvetronic system. The levers and shafts wear out, which the tolerance between the two not allow the valve to fully open as it should. This typically starts to occur when cold only, and when the engine warms up the tolerance is less, therefore the engine runs smoother. They are a known problem with that engine, especially on the early production N62 engines. This is a labor intensive and expensive job to perform. You can google the repair procedure, there are many writeups on the situation.

Hope this helps, please be sure to leave a positive rating, as this is the only way I receive credit for my work and time.