p0170 code w/multiple misfire codes
 

I've got a '97 C230 with a CEL, codes p0170 (fuel trim bank 1) and p0300,301,302 (misfires on cyl 1,2).

I did a search before posting, found one saying the air mass meter is the likely culprit.

I replaced my AMM the other day, with a used one that came from a misdiagnosed MB elsewhere. The light came back yesterday.

Is there another way to diagnose the problem? Values I can observe with a code reader? (self adaptation, O2 sensor values, etc)

Thanks,

When you rechecked the codes, were they the same or did they change? I would bet the fuel trim code was gone.

That said, I would look long and hard at coil and wire resistor ends.

They fail frequently.

I just had the codes read today. Actually it was more the opposite, a while back it was just the fuel trim code. Now it's fuel trim and misfire. I changed the spark plugs a couple of days ago, so I know it is not a bad plug.

Is there any way to test the AMM? I don't even know if it's sending a signal anywhere.

Another piece of data. . . when I chagned the spark plugs the other day, they were black around the end except for a small area at the tip of each electrode tip (I had the Bosch 4 tip kind).

Is there a way to check the O2 sensors or to see what the mixture is running?

Thanks

I read somewhere that the fuel trim can be reset somehow with the factory diagnostic tool. Is this a requirement when you change MAF sensors?

I changed out the sensor, but that's it - didn't reset anything.

Anyone?