Acklam1967

Hi, I'm having problems,or shall I say my local mercedes dealer are.I have a misfire problem and no one can find the fault,any ideas guys......it has had a kleeman map and exhaust fitted

ToXicXxX

Replace spark plugs, replace/swap coils, clean MAFs, check for O2 codes, check for fueling codes.

That should get you started

abcut973

Are you saying your MB dealer cannot find the problem???
Either way as mentioned above pull the error codes but most likely it's either your plugs/coils, O2 sensors or fuel system. GL

Acklam1967

The dealers can't find the problem,3 weeks now,all they want to do is charge me money for parts that aren't really the problem.The latest off them today is the compression is down on 2 cylinders....what's that got to do with a misfire

abcut973

Loss of compression can be the root cause of misfire as well. A cylinder losing compression means the cylinder loses air/fuel mixture before behind ignited. Hence the misfire.
Are the 2 cylinder adjacent to each other? If yes it could be a leaking head gasket as the fault.

Acklam1967

Not sure which cylinders it is,it sounds expensive if it needs a head gasket.They said they want to strip engine down....I obviously said NO...what else could it be ?

abcut973

Looks like they narrowed it down to low compression on 2 cylinders.
It depends how confident you are and what is the relationship with them.
I don't know why they would tell you it is a compression issue if it is just a spark plug/O2 sensors or else?
Just ask them to show you the test results for the spark plugs or O2 sensors if you don't feel confident.
How old is your car? Don't you have a warranty or extended?

Acklam1967

It's a 2009 with stage 2 kleeman conversion,I only went to the dealership to keep up the service history...warranty ran out when it did have a warranty they only say ' because it's a used car warranty it's not covered ' I really don't have faith in them ,I had issues with a cls 55 amg a few years back with a problem they could,nt fix.Luckily I got out of that car after a 2 year fight withe finance company as the garage I bought it off sold me duff car,I got my money back.All dealerships think about is money,money,money..don't know if that's the same in the usa but here in the uk it's like that

abcut973

Some MB dealerships in the US are more about their money than others like anywhere else in the world.
Your best bet would be to find a good "indie" shop knowledgeable in german cars. But yeah if the diagnostic is true the only cure would be to changed the head gasket if the gasket is gone. Ask them for the compression test results.
What you can do is plug in a OBDII tool to check the codes which will help you identify the cylinders/bank in fault. Then check the state of your plugs for the corresponding cylinders. That would be a good start to double check what MB would have done.

Acklam1967

I will go to garage tomorrow and tell them what you have said....thank you