I am buy no means an authority on this, but the 6 cyl mode is a limp home mode that I believ is performed by shutting off fuel to the injectors. I belive it will go into that mode when such things happen such as ASR or ESP has a fault of some kind, making the car a little to over powered to be driven by the average. I am not sure if turning of ARS or ESP will give you back the other 6 cyls but its worth a try.

Essentially the engine is two straight sixes and one can be turned off for other emission or performance related resones as well. I am not aware that a side can be turned off for economy reasons but I could be wrong.

Also my understanding is that with one side off you will still have about 150HP or so. I would think it would be able to do over 70.

Since you mensioned both coils, I belive you are talking about the older system with a distributor. Please give us the year.

John Roncallo
Fast becoming an M120 expert.