A misfire can go un reported by fault code for considerable time. There is a level of misfire and a rate of occurance that must be exceeded and the earlier the car the less critical the criteria. A 96 would probably be the first year for an "S" class to report at all.

Unfortunately, real tooling will probably be required to observe the problem. Either the smooth running function on SDS or the ignition firing values in EI if it isn't a ME car. it could also be a throttle problem and not be a misfire. The condition needs monitoring with the appropriate tooling and TRAINING.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician