Mercedes-Benz W210 petrol engine misfire
What causes misfires and jerking in a W210 petrol engine?
The most common causes are a faulty ignition coil, worn spark plugs or plug leads, and an intake air leak. The symptom often gets worse as the engine warms up. One coil serves two plugs in the M111 engine, so the fault may be in only one of them.
How do you find the dead cylinder on a W210?
The fault codes tell which cylinder has the misfires. The coils can be swapped with each other one at a time: if the fault moves to another cylinder, the coil is faulty. The spark plugs should be replaced first, and the plug leads checked at the contact surfaces and by measuring.
Can a misfire damage the catalytic converter?
Yes. A cylinder running dead feeds unburned petrol into the exhaust system, which strains the catalytic converter. The engine should not be driven for long before all cylinders work. Other causes such as the mass air flow sensor or the head gasket can give the same symptom.