when driving the car feels very underpowered as if it has a major flat spot in all gears i've changed one of the coil packs that seemed to be causing the misfire but only seems to have solved the problem when idleing any help would be appreciated
ive never heard of a snapped earth wire causing a misfire but it needs replaced as soon as possible anyhow as it will cause many other problems, like poor starting etc. id start by replacing the earth lead, checking/replacing spark plugs and leads etc as a starting point. my rule of thumb is always start with the simple cheap items first. they cost less to replace and are usually the more likely culprits!
so far i've checked for spark etc checked that power etc is getting throught to the coil packs and replace the pack that feeds pots 1 and 4 and everything seems fine i've traced the wiring back and checked power to all wiring next step i'm going to try is to change the ecu and see what happens there
I've ran a multi meter over the various wiring etc there is power to the coils and from the ignition module etc could this be a case of needing a new loom? which sensors would need to be checked etc this is my first mercedes so i'm a bit of a novice where to look on them
I have just read your post regarding misfire and car being very underpowered
I had the same problem on my c200 auto with the car being very underpowered and the engine would not rev over 4000 rpm in kickdown mode which made it feel like it being held back .
This is the reason I joined the forum and reading through the posts it pointed to a MAF sensor problem , I tried cleaning the sensor but this made no difference to the car.
So I purchase a new one from a ebay seller for 30 pounds which I understand to be a cheap copy of the original bosch one.
I fitted it this morning and it transformed the car with better gear changes and full power restored.
So my advise would be change this sensor first.
top of the engine is silver i have so far removed the loom that sits inthe black plastic that connects to the injectors etc and stripped the sheathing but it all appears fine so i'm going to check the loom that is attached to the coil packs etc now
you can read blink codes on this model. if you connect an led or ideally a power probe to socket 8. with ignition on, short pin 8 to earth (pin 1) for between 1 and 5 seconds. the probe will blink a series of codes if faults are stored - you have to keep going through the procedure until you get the first code again. to erase it`s the same but 5 - 10 seconds of earth. if no faults stored or you have cleared them it will blink just once. at least that`s how i remember it!! you will have the diagnostics available on your car. and i believe you have pms, so no air mass sensor - that`s your throttle body btw.