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Discussion Starter #1
My car is 2003 c230 with about 90k .My engine light came on and the car started idling roughly. I checked the codes and it reported a p-0302 (cylinder 2 misfire). Restarting the car cleared the rough idle, with the CEL still on (occasionally it will go through a drive cycle and clear the CEL, but only every once in awhile). So far I changed all four spark plugs . I swapped the coils between cylinder 2 and 3 to see if the problem followed the coil, it did not. I replaced the fuel filter (thought maybe the #2 injector was more sensitive then the others.)
I did this work over the course of the past two months, and the only code that was logged was The p-0302. This code was only logged at idle (the misfire never occurs under high rpm's/loads) and more prevalent after being on the highway and coming to a stop at a light shortly after exiting.I saw other people complain the same thing with the same car but I never heard what is happening finally to fix the issue .could you please let me know what is the problem ,(sensor ,fule injector ….)
Thanks
 

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Very common problem, usually caused by one of two things. A: carbon build up on the exhaust valves, causing the valves to stick intermitantly. Usually can be fixed with a fuel injection flush and running the crap out of the engine (e.g. running it at 4000 rpm for about 10 minutes). And then there's B, which is more common: Your valve guides are worn, which caused your valve seats to oblong. A new and updated cylinder head would be in order. Once again, it's really common on the 271 motors. We have a guy in my shop that replaces about 1 or 2 cylinder heads on these things a week.
 

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Discussion Starter #3
I tried A: noting changed so far .I just use fule addetive from mercedes for that.do you recommend any things stronger . B: the milage in the car is 90000 Km .is it still under waranty ? ( here in Canada full waranty is 4 years 80000 Km for most of the things that I finish that ) and I know there is some more waranty for power train and these stuff ( i think 5 years 100000 km or something like that ).do you know this problem can go under power train and ... i am going to look at waranty booklet as I believe in Canada it cost me more that 4000 $ .Thanks for your reply .
 

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I talk to dealer and they told me cylinder head and these stuff is under waranty for 5 Yr 120 KM that is a good news for me .but they mentioned they did not heard any things about defective cylinder head and .... .If you could please send me more information like DTB about this defective stuff or new and updated cylinder head i am going to ask them to replace it if they diagnose some thing else .
Thanks a lot
 

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The bulletin is P-B-07.61/46j. It goes threw the basic tests and refers you to different repairs according to the results. Whether being revving the engine, replacing the valve springs, and ultimately replacing the cylinder head.
 
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