THANK YOU.
again, (in my amateur logic), I keep questioning WHY I only get the error in the same bank
1) A bad/fouling spark plug.
I swaped the spark plugs between banks
2) Weak Coil on one/multiple cylinders (I've already dealt with this on my 60K mile 4.4)
I swapped the coils between banks
3) Dirty/faulty injector. The spray pattern can go from "Mist" to "Stream" with very little dirt, and/or have the the injector never completely "seal" between pulses.
I swapped the injectors between banks
4) Valve seal leaking, and introducing oil into the cylinder
5) Weak compression in a cylinder/cylinders on that bank (valve seats, rings, etc.).
You'd probably notice a decent "oil burning" smell on those last two.
MY FEAR, but no excessive oil consuption or smell, spark plugs looked basically all the same
It's good that you swapped the O2s to start with, ruling out a bad sensor.
It all started after all O2 sensors were changed due to milage and a non service light error code telling me "insufficient heat output O2 sensor after cat bank 2 (the same bank I am having issues with)
It's all just a matter of diagnostics/ruling out what *isn't* wrong to narrow the possibilities.
Do the easy stuff first.
"going to try and do a smoke test and WISH i see the "smoke signals"
My computer with diagnostic program mentioned to look for leaks between cat pre and cat post- dont see any and no change in exhaust sound. Am I correct that is the job of the catalytic converter - to burn up any fuel left in the exhaust?
The TSB does not include my year range - but much appreciated. The working link is:
http://www.bmwmotorsports.org/pdf/misc/120704.pdf
Thanks,
Kevin