Injector help please
 

Hi everyone,

We are really struggling with a misfire. Here's the history, CLK320 2001. Started misifirng on cylinder 1. Started with the simple stuff and changed out the spark plugs and cables. Still misfiring on cylinder one. Ok so got a new injector (not bosch but correct one for the car as couldn't get bosch same day) and put it into cylinder one, the retainer clip got a little out of shape in the process. Anyway we thought this fixed the problem and car drive perfect that day. Next morning misfire on cylinder one again. We tried a few things, first off we swap injector one and two and also switched the coil packs. Reading for misfiring for cylinder 2 so we got exciting thinking maybe it's just the coil pack so we swapped the coil packs back around but it still read misfire on cylinder two with the new injector. Put a new retainer clip on to see if any difference, this was a BWD retainer clip so it is the spurious part not the original because again it could not be got in store. The spurious injector that has gone in the O ring on the bottom does not sit on it tightly , when we pull the fuel line up to access the injectors the O ring does not come out with it. Is it possible that it is definitely the injector causing the issue and the spurious injector is either faulty or just not good enough? If so why did it drive perfectly the first day? Any help welcome

I would double check coil packs and wires, because honestly i think that in vast majority of cases the missfire is directly correlated to electrical issue[s].
Little story of my car, about 3 years ago i was driving it around in extremely dusty, dirty and hot environment without an airbox, i was doing donuts and stuff ( not sure what i was thinking )... so few things happened as a result of that, cam gasket started leaking oil, oil went down in sparks, MAF sensor literally died, because all that extremely hot dust was going directly into throttle body through MAF, without any filter or even tubing. Got missfire i think in 3 different cyclinders.
So, changed the gasket, changed spark plugs (all 12), changed MAF sensor, properly installed OEM airbox with new filter, "cleaned" cyclinders with fuel additives, car started running smoother, but still had missfires, apparently coils were half corroded, changed those coils, still had a missfire but in just one cyclinder, the coil plug wire was damaged, changed that wire and everything went back to normal, no issues since then, didn't even touch the fuel injection system, 3 years and counting

Thanks so much for the response, we had already changed coil packs around to see if the misfire would follow it but it didn't , the misfire stayed with the new injector when we moved it from cylinder 1 to cylinder 2. I just can't get my head around how it ran perfect with the new injector on day 1 and then it returned. Will we check the wires again