My check engine light came on a few days ago on the 2002 W208 CLK55 AMG. I had the codes read at AutoZone and the guy stated there was a misfire in all the cylinders.

So the following weekend I replaced spark plugs (Denso), spark plug wires (Magnecor), fuel filter (Mahle) and MAF (Bosch) and reset the check engine light.

About 15 miles down the road the check engine light comes on again so I get the error codes scanned and its the same issue - misfire in all cylinders.

I'm trying to figure out if any comrades on here have experienced such an issue or similar and what they did to resolve it or if I could be pointed in the direction as to what to look out for.

Any help is very much appreciated.

Crank Position Sensor?

other than check engine light, are you noticing anything wrong with car?

Thanks Critter that's something worth looking into will add to my to do list.

Nope - other than bad gas mileage, car seems to drive fine and that's what keeps baffling me as I initially thought it was a coil pack gone bad or 02 sensor.

i had the same code when i first put supercharger on. I cleared the code and i was good to go.

so I reset/cleared (gracias to 2Precise) the codes and now I have two new codes P0432/P0422 so I'll be switching the new MAF out to see if that's the culprit before I start looking into new cats and 02 sensors.

Be sure that you get oem MAF..not ebay special.
Also, check that the rear of the air filter is securely seated in MAF body...also, check for vacuum leaks.

after being on this forum for many years, the majority of the O2 sensor bad codes turn out to be bad MAFs/improper seating of air filter, or vacuum issues.

That's pretty cut and dry,
The only oddball problems that might cause this are wiring harness problems, low voltage conditions on random circuits, fuel pump or regulator issues.
Did the old plugs look normal or dis-colored?
The CEL is really a nuisance on these cars most of time, I reset mine and it comes back after a couple of days normally after driving in traffic. Highway is OK and all systems are go on the readings from OBD2.
Its about time for a cat juking event. LOl

The 100,000 mile Iridium tune up plug is over rated, Aluminum and metal do not work well together after this kind of time and temp. Electrolysis is evident and the head will suffer. I wouldn't go past 40,000 without tuning.

Cheers, Gator

so so it looks like its my cats that are the culprit so I'll be replacing them with the magnaflow 59950 and 59975.

Unfortunately I cant seem to find the magnaflow 59950 online anywhere. The closest I could find was the magnaflow 59959 which has a 3" inlet and outlet. I'm not even sure if the 3" (59959) will fit the CLK 55 or not so anyone please feel free to chime in if you know the exact sizing for the right side factory cat.

Also anybody else have any other aftermarket cat recommendations other than these two?

Thanks for all the help so far - appreciate it.

I'm having the same issue--new air filters, new sparks and wires and still misfiring. But I'm not getting a CEL. Going to try cleaning the MAF, but I doubt that will make too much of a difference. Mine also runs fine at speed; other than feeling a little down on power it seems okay. But it shakes at idle and you can clearly hear popping coming out of the air intake with the filter off.

Popping out of the intake could be a few things, timing out of sync, intake manifold leak, maybe gaskets or burnt valves. Do a compression test for proper valve sealing. Pull a valve cover to see if the chain in tight. Does not sound right popping through the intake.
Spray some brake cleaner around the runners to see if the manifold is sucking air at idle.
Your car has a supercharger on it so a leaking gasket would be covered as the revs increased by charger pressure
Hope this helps.

Thanks. I've sprayed carb cleaner around and didn't see any vacuum leaks. It doesn't have a supercharger btw. The car feels a bit stronger with the new plugs / wires but still vibes at idle. Though it seems to be a different frequency, if that makes sense.

The next I would try is using intake and choke cleaner, comes in a spray can, from Autozone or similar. This is used to clean the throttlebody, on the back side of the throttle plate oily residue collects and starts to restrict the air flow at idle causing various computer changes to control idle. Remove the intake tube going into the throttle body and have a friend turn the key on and depress the gas pedal., this will open up the throttle plate and allow you to use the spray cleaner , use a cloth covered toothbrush to clean the back of the plate and the inner barrel where the plate closes on, it will be black with this sludge material. Repeat until shiny like new. release the throttle, shut off the key. Reinstall all pipes and restart, may run funny for a bit but will smooth out quickly. You will be surprised at how much gunk in on the plate and inner barrel.
If you use a mirror first to look into the throttle body the rest is self explanatory.
Good luck.

Still do not like the popping in the intake part.

Okay jus a guess sensor in side fuel tank and your cats could be damaged and going bad make sure you gas cap don't need replaced and is always on tight I had same issues changed to sensor new gas cap and always closed tight fixed my problem than bam cats went bad