hello guys i have a 2004 MB C230 kompressor check engine light came on so i took it to auto zone to get the codes from the computer and this is what i got p0301, p0302, p0303and p0304 which translates to those cylinders misfiring I have replaced the spark plugs about 2 months ago "they were in bad shape before being replaced" any ideas where to start ? what sensor could be causing this problem ???

 

Have you tested the ignition wires and coils?

 

they look in good condition when i changed spark plugs not so long ago i will check them today again maybe i missed something

 

I just had this problem. Took it to the dealer they used a boroscope on it turned out to be a cracked valve and worn out valve guides. Bad gas creating carbon deposits was the cause.I had to replace the head. The cost was to the tune of 4 grand. After that it has run great. I hope you dont have the same problem.

 

Similar story here, had a recurring cylinder #1 misfire condition that was triggering the CEL, scope showed buildup in the head. Hard to say which came first, the gunk in the head or the misfire, but it worked out to be a cycle (valve not seating >> misfire >> more gunk >> repeat). A few things that worked for me in combination:

1. Treat several consecutive tanks of fuel with good valve cleaner (I had good luck with this one)
2. Dealer recommended running the engine at 4k RPM (the rev limiter kicked in at this speed when the car is stationary) for a 10 minute period.
3. Change the fuel filter!

The above three in combination did the trick. Alternate suggestions were new valve springs ($$$), a rebuilt head ($$$$), both of which I wanted to avoid. Good luck.

 

Could you please let me know what kind of a job changing plugs in a C230K is since you have done it yourself?
Any help would be appreciated. I'm mechanically inclined and build my own hot rod V8's, so no problem there.
Just want to know what I'm getting myself into before I go running off to the store and buy the plugs.
Thanks.

 

Spark plugs on this I-4 are easy to access and change. Take the top red cover off. Remove the bolts from the coils (torx socket but small metric worked for me). Pull one plug wire/assembly at a time with a gentle but firm upward and slightly twisting motion. Change one plug at a time so you keep wiring correct. Use a torque wrench to make sure don't over torque. Be extremely careful threading in new plug. Thread it by hand all the way (many turns!)until it gets hand tight before you attach the wrench. If in doubt at all, back it out and start over so that you don't strip the threads. Stick with the factory recommended plugs. Don't buy the fancy ones. Supercharged engines don't like/need the fancy super-plugs like Iridium.

 

Thanks......gonna go get some stock plugs to replace and do the job shortly. I have all the tools necessary I'm sure.
Some have suggested replacing the wires, especially at 100K as my engine will have shortly. I know it's always a good
idea, but sometimes I think, "If it ain't broke, don't fix it", but I know better. Do it once. Do it right. Do it all. Right?
Hate doing the job twice.

 

simple simple if fault codes are all cylinder misfirin its the air pipe leaking ,the pipe is under the air box. to check this you need to remove the air box and the shape of a pipe looks like hoky stick it comes out from engine block to intake monifold have fun changing it good luck............