hi all need some help with my sl55amg . supercharger not working all the time when i load it and work the supercharger hard then come of the gas for a few seconds and put the power back on there is no supercharger power . let the car cool for a few seconds the boot it its back full power . was told that the s/c water pump was dead put new one in checked the fuses all good .done rd test still the same help please also have a code p2027 egr vacuum transducer , whats this mean ????