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I took C230, 2006 to Pineville NC stealership(no warranty). This is what they found:CEL was caused by:-0745 self-adaptation of mixture formation for enrichment at idle for the right cylinder bank is above the permissible limit(P0171)-0749 same for the left side(P0174)-2091 the mixture in the right cylinder bank is too lean when idling-2095 same for left bankAccording to their report, self-adaptation at idle is supposed to be between -4.5% and 4.5%. they measured 6%. Fuel sample was OK. They reset self-adaptation after what engine started to shake, CEL came back on and threw misfire for 4 cylinders. before this, car never had misfire code.Intake manifold pressure(which has to be less than 500) was measured at 610(at fauld codes decription it was 670 and as high as 890.Anyone has idea what is going on with this engine?They replaced MAF sensor but that did not help.Thanks: Dan[/align]

 

There is definitely something still wrong with the car; you already know that.
The MAF sensor would have been my first thought as well based on the symtoms,but not this early. I think you have another problem which may be thowing the techs off base, such as a damaged wire or connector, perhaps burned, chewed, or pinched. Somebody is going to have to keep looking for the problem; too bad the cars are so complicated now. Be sure to get your original MAF sensor; you can use it for trouble-shooting in the future, or as a spare.

 

ive seen those motors with cracked vacuum hoses at the back of the valve covers on the back side.. also those cars have issues with the cam adjusters.. you prob already had them repaired. Ive also seen bad engine control modules too. and also worn balancer shaft gears too..