86' 300E rough idle & hesitation resolved!!!
 

Just wanted to post this for those with the same problems. I'm an average DIY guy and try to fix the minor things with my car, but sometimes I take it to a mechanic when I can't figure it out myself.

Anyway, lately my car would idle roughly and sometimes it felt as if it was struggling to accelerate. I though it was the fuel pump & filter, so I changed that....guess what....no improvement. GREAT. That put a $300 hole in my pocket.

I was going to start replacing the sensors and relays, but that could cost too much. I figured that maybe it would be better if I just brought it to a mechanic.

Anyway the first time I brought it in, he tested the fuel line, cleaned out the injectors, then changed the oxygen sensor. He had a hard time diagnosing the car's problem because the problem was intermittent. Anyway his "fix" cleared things up a bit, but after a few weeks, the problem came back even worse. I brought the car back to him and he "scoped" it. Turned out to be a bad coil. The spark plugs were changed too (They were over a year old anyway).

I should have brought it in to the mechanic in the first place. Damn it! Well, at least I've learn more about my car. The fuel pump was noisy (sign of impending failure) anyway so I guess it's o.k. that I've changed it.

I hope this experience will help others clear up their problems.

That's great news, now if I could just figure out my gremlins.

Do you hapen to know why the newer W124 cars came equipped with 3 coils instead of 1?

I haven't changed mine before. Maybe I should put an ignition coil on my "parts to buy" list too.

Newer 124's use the M104 with uses 3 coils for fire 6 plugs with no distributor cap. They are electronically fired. The earlier M193 uses one coil and a dist. cap.