im having troubleshooting misfires no my car. 2008 335xi, 104k miles, FBO. When it is about 40 degrees or colder out, my car starts up like normal and within a minute starts hesitating and throwing a check engine light. When I check the MHD serval codes come up to say multiple misfires, or misfires on cylinders 4/5/6. More often, cylinder 6 will keep throwing a code a few more times. Obviously the car runs very rough until I clear the codes. Sometimes only need to do it once, sometimes five or six times.
Reading around it looks like a ton of problems could cause this, which is annoying... I tried swapping the front and rear plugs, 1-6,2-5,3-4 but the misfires did not follow the plugs. I swapped the front wideband sensors, couldn't swap the rears because the plugs are not interchangeable, and no change. I checked all six plugs and all but cylinder one look the same. Cylinder one looks to have an injector that is leaking and wetting the plug, another issue for another day. I cleaned and reinstalled the vanos solenoids, no change either. I have tried going back and forth from a more aggressive tune to stock, back and forth and no change. Also tried to tighten all downpipes connections.
So I tried coils, vanos, front widebands, looked at plugs, changes tune to stock, tighten for exhaust leaks, and nothing... looking around several other things look like they may cause this; PCV valve, valve cover, exhaust leak I didn't find, replace wideband sensors, new vanos solenoids, adjust downpipes fix thing, new coils, new plugs, new injectors, new hpfp...? That is a huge list of pricey parts to randomly fix without nkowing kit will even fix the issue!
Please help!
Reading around it looks like a ton of problems could cause this, which is annoying... I tried swapping the front and rear plugs, 1-6,2-5,3-4 but the misfires did not follow the plugs. I swapped the front wideband sensors, couldn't swap the rears because the plugs are not interchangeable, and no change. I checked all six plugs and all but cylinder one look the same. Cylinder one looks to have an injector that is leaking and wetting the plug, another issue for another day. I cleaned and reinstalled the vanos solenoids, no change either. I have tried going back and forth from a more aggressive tune to stock, back and forth and no change. Also tried to tighten all downpipes connections.
So I tried coils, vanos, front widebands, looked at plugs, changes tune to stock, tighten for exhaust leaks, and nothing... looking around several other things look like they may cause this; PCV valve, valve cover, exhaust leak I didn't find, replace wideband sensors, new vanos solenoids, adjust downpipes fix thing, new coils, new plugs, new injectors, new hpfp...? That is a huge list of pricey parts to randomly fix without nkowing kit will even fix the issue!
Please help!