MAF showing high air flow - Kompressors

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Unlike normally aspirated engines, the Mercedes Kompressor style system has a long line of piping and an intercooling radiator between the Air Flow Sensor ( MAF ) and the throttle butterfly valve. The supercharger keeps this piping full of pressurised air from around 5 psi at idle to double figures at higher revs. The four cylinder models should show an air flow at idle of around 4-5 g/s ( 18 Kg/h ). If there is a bad joint or split anywhere in those large pipes in front of the engine the supercharger will happily try and supply more air up to around 20 g/s. The mixture control system will have a nervous breakdown and throw an engine light Happily the car will still run and get you home - just a bit sluggish. Even the emissions will still pass an MoT but the warning light will not. Any decent OBD scanner will let you see these figures under Live Data. The pipe junctions which use the spring clip have rubber seal rings which get soft and swollen by the oil vapours and make it difficult to replace securely. Order a couple of new ones before you need to dismantle the piping - e.g. when replacing the multi vee belt. Checking this carefully may save another hole in your wallet.