LPBenz19

I have had a CEL on a misfire on cylinder 6. I have replaced all 12 spark plugs and replaced the coil on cylinder 6. The mechanic told me he's still getting misfire on the car and needs more time to figure out what the problem is. He said he tried swapping out coils and still have the problem. He said it may the injectors and a list of all other things. He cleared out the CEL and I put some Techron fuel injector cleaner and the CEL never came back on with little rough idling here and there. Now every other day the CEL comes on usually on the highway doing 70mph and starts to shake on take off from a stop like its gonna shut off. Can someone please help and tell me whats making to happen
Its a 02 c240 with 95k

Moviela

Check the crankshaft position sensor, then measure the fuel pressure. Does it show any codes other than misfire?

samaritrey

Also switch around spark plug wires. I just replaced mine and it fixed a hesitation at start up and random stumbles.

LPBenz19

No other codes other than a misfire on #6. Thanks samaritey I'll try that. Could it be the harness?

LPBenz19

Also the CEL comes back on and misfires really bad only after being in the highway and over 70mph and then its slow sluggish and sputters. So confused the next day and it's fine and no CEL

02C240

also make sure the two wires to Cyl#6 are installed correctly into their respective ports, A and B.

Glyn M Ruck

Have you replaced both plug wires on No 6. Your car is overdue for wires.

LPBenz19

Wires are good and on their right ports. Still starts to misfire after 70mph and goes away the next day wtf

Glyn M Ruck

Going out on a limb here. Are you absolutely sure that the airbox is clipped down tightly over the MAF at the rear of the engine? If it is not sealing over the MAF it causes the MAF to hunt with all sorts of spurious drama & codes.