I have a C43 with a E55 engine(2001) the car runs great up until about 4 months ago. I started to get PO170 and PO173 codes along with PO446.

I had been upgrading the car chassis and sensors all summer long to bring the car back up to close to new spec. Replaced all the subframe bushings, control arms bushings, etc.

On the engine I repaced the Crankshaft and Camshaft sensors, the MAF and cleaned the MOT valve in the engine bay. I also repaced the four O2 sensors. I keep getting the PO170, PO173 and PO446 codes.

So Booked an hour or two at the dealer to see what they could find. MAF was reading 1.1 volts and giving out a 4kg/hr reading for air flow and the injectors where outputting enough fuel to keep the motor very rich. Plugged in a brand new MAF off the shelf and got the same readings 4kg/hr or minute, spec is around 16 to 18kg/hr or minute. We went through all the electrical lines as they run from the MAF connector to the ECU and all of them checked out with no shorts, resistance, etc. In short the MAF wiring was in good shape.

Any clues as to what would cause the MAF to read such low air mass readings, with the O2 sensors working correctly and the wiring being sound?

At 4kg/min or hr the car should not even run.

Last thing, with the key in the on position the fuel pump does not prime the system, so 0 psi at the rail. With the engine on, the fuel pressure jumps to approx. 400 kpa or 58psi. The charcoal cansister valve behind the rear wheel fender cover will click on and off when given a test voltage of 12 volts.

Anyone have any suggestions?

Sincerly, Jeff