Ok, 1995 C280 and the check engine light comes on. First the #4 cyl misfires so the plugs are replaced as well as the wires leading to them also had the coils looked at and seem ok according to dealer (latest and greated version). Light comes on again few weeks later on for the #1 cyl. Certified MB dealer cannot figure what is wrong and why I keep getting these misfires every couple weeks. The light seems to go on shortly after the car is started (COLD) and driven several miles. The light comes on, the cyl. shuts down apparently the car rumbles. Shut down, restart, and everything is fine, except the damn Check Engine light is now on which means another trip to the dealer. This is the 4th time..Does anyone have any ideas what to look for? What else can it be? The dealer is stumped as they have tried everything..anyone have any idea at all? PLEASE! I cant stand making an appt every other week to have the light switched off and something must be wrong! AHHHAH!!!

how many miles are on it and if it is over 80k has the O2 sensor ever been replaced?
Jim
'95 E320
'97 CRV

First of all did they tell what codes are triggering the engine lamp? there are over 50 possible codes with this engine & ODB2. If one of the codes is P0 300 OR P0 30(?) then this is a misfire. Lack of fuel pressure(fuel pump or filter), fuel injection duration(air mass sensor), ignition system(already tried that) or engine wiring harness problem.

The Code noted on my invoice is as follows...
110,000 miles...
Found DM Code PO304...Replaced all plugs (it was time to replace) and replaced #4 Spark Plug resistor end

They did replace the #1 spark plug resistor end after this happend again to the #1. Good idea about the fuel filter/pump. I will at least ask the question next time.

The weird thing is after I bring the car home it usually happens the next day after the car is cold. I drive 6 miles or so, the car is usually already moving 2 or 3rd gear, i feel a slight hesitation, and know the light is about to come on, and boom it does. The car starts to rumble, I pull over restart and it goes just fine. It does this every once in a while after that (the light is on until I go to the dealer and have them reset)

I think they checked the wiring harness too. O2 sensor replace couple times under warranty and that usually does not affect ride in any way...I think you are spot on with the fuel delivery issue. Any suggestion on what to try first, maybe what is cheapest. I know if I suggest pump and filter I will probably get both and pay for both. I am not too fond of the "lets replace everything, I pay for it, and see if it works ok" option...THANK YOU THANK YOU!!!

Well,

I sounds like they found the right code, but not the right resistor end. On the 104 engine, there is a tell tell sign to look for. You have to pull the plugs and keep them in order. You will be looking for the plug(s) that have a streak on them. I have seen this over and over. I a plug or plugs has the streak, replace that respective end and clear the codes, (assuming the coil is OK) ...9 times out of ten it is just the end.

Clear codes and all is well.

There is not a really good way to scope this engine, so the tech may be guessing unless he knows this trick.