barcheta

At first I replaced the one coil with an aftermarket one supposedly right for this engine. When I got mis-fires on all the remaining coils I went ahead and replaced the rest figuring well hey they have over a 100K on them why not. The over current in turn must of roasted the probably already weak ECM. The New ECM doesn't seem to like the 1501980 original coils but it does seem to like the 1502780 coils. The aftermarket coils I put in are Beck/Arnley. I've used their stuff before in other cars with no issues. The OEM Mercedes coils are made by Delphi. The resistance on the aftermarket coils in addition to the bad misfiring coil produced a cascade effect.

In fact, I did throw all the old OEM coils back on (with the new ECM) and it ran as bad as it ever did with the old ECM. Problem is if one (or more) of them is indeed bad I have no idea which one. And at this point I'm not willing to play anymore guessing games or screw with a good baseline. So at this point I think new new is the way to go.

barcheta

Followup.... all new MB OEM coils put in.... was still running like ****. As I was poking around in the engine compartment checking my connections because I was extra extra careful about handling the coil plugs with kid gloves. I discovered when I pressed on the connector plug for coil 5 the car ran even worse than it had been. I was also getting another misfire on cylinder 6. So off to MB of Catonsville. Turns out the number 4 pin the plug for cylinder 6 was crushed. not sure how or when it happened but the tech there replaced the pin cleared the codes and now all appears well.

I do notice an ever slight hesitation at idle now though..... no codes... except for the seat of my pants. I'm guessing I may need a new set of cats or at the very least some O2 sensors in the future.