need help with 96 S420
 

one side of the engine does not seem to be firing and one mechanic thinks it it is the wiring harness and another thought it might be the coil pack? any suggestions? also the power for the locks windows etc is not working right. could this be connected?

Sounds like you need a mechanic the understands Mercedes Benz. I mean guessing is a little silly, no. A qualified mechanic can easily make a diagnosis.

Locks are vacuum powered. Another thing the qualified mechanic would understand.

Steve
'97 S320

One side of the engine misbehaving can be a timing chain that has jumped a tooth or two on one side. This would typically happen in conjunction with a broken upper timing chain rail. It is not at all an easy diagnosis but is quite apparent upon removal of the valve cover.

My suggestion is to check your wiring harness and check your ignition coils. One of them could be right. For wiring, check the wires to the air mass meters, the electronic throttle actuators, and the fuel injectors. If multiple cylinders are misfiring, it's unlikely to be ignition coils. Each cylinder has its own coil, and it would be odd for many of them to fail at the same time. How are your spark plugs? Any OBDII misfire fault codes that will tell you which cylinders are having problems?

Brett