02 e320 4matic misfires under heavy accelaration at about 4500 rpm. misfire codes 300,301,302,303. replaced cats swapped injectors, coils, plugs, wires from side to side. new mass air flow installed. anybody have any ideas or have sen this before thanks in advance

 

Hi,

Subject to your response it doesn't leave much.

However fuelling (which if incorrect = misfire) also involves the O2 sensor.

Need to determine the O2 sensor output LH vs RH since one may be on the way out.

If you don't have access to a data reading scanner try a swap LH to RH. Note the sensors will be VERY tight (don't use oil etc since this can wreck the sensor). need to gain good access with a ring (no drop offset) or split side deep socket.

You didn't mention whether the CEL illuminated but I guess so since you had misfire codes set.

Incorrect "signature" for MAF but you have determined this anyway. BTW was it a genuine MB/Bosch MAF?

Stuart.

 

Have you had the computer tested with real MB scanner. You may have fixed the problem and don't know because the computer canshut down multiple injectors and not turn them back on without the proper scanner....