Having a MARE (MAF related)

I tell you what, this exige/audi lark isn’t half giving me some challenges!.
When it is working, its great, unfortunately its not working more often than it is!
Fitted a wideband and could see fuelling was very rich (7.5-9 AFR) was told it should be 10.5-12.5.
Did some VCDS logging and the flow rate through the MAF at WOT was a tad low (about 170 g/s) so I bought a new genuine Bosch MAF.
Drove to work (fine), changed the MAF, car started running very poor, massive over-fuelling, wouldn’t run on anything but WOT.
So put old MAF back on - same poor running.
Plug looked a little dodgy so cut back the wires, put new pins on and tried again - still poorly.
Its running a Bosch ME7.1 ecu on a IHI VF34 turbo.
I am sure the new Bosch MAF would have been tested before it left the factory? All the hologram seals were in place when I bought it and I checked out the serial code on the Bosch website so its def genuine.
No relevant faults showing on VCDS either, but running like a total bag of sh*t. Lots of black smoke and struggles to idle, running on part load it surges massively.
All the plugs are fouled, and you can feel that the misfires are across all cylinders so not a dodgey coil or plug.

Any ideas? My next plan is to trace the wiring back to the ecu and also compare resistances across pins on old & new MAF.
Anyone got any other bright ideas??


No errors logged on the ECU?

I know very little on the ME stuff

in case anyone is interested - maf issue resolved.
It turns out that the MAF must not be rotated with respect to the intake pipe from its position when mapped.
This is due to variations in airflow across the cross section of the pipe - I guess the MAF sensor is not absolutely central in the pipe!

Wow, interesting. Didn’t know that.