unstable idlling-stalling im going nuts

[rumpfy]

Have been doing some work on a Ford Focus 2007, suffering from High fuel consumption. In spite of Ford saying the throttle body doesnt need cleaning (the computer adjust itself!), the fact seems to be that fuel consumption is increased if this is not clean. The Focus went from around 10.5 L/100Km on a trip, down to 6.9/7.3 on a trip.
The question I have about the throttle body on Magna, is 'Why does the throttle body/MAF fail". Or, in other words, how to fix it? I think the MAF has a hot wire and a reverse biassed diode. There is not a lot to go wrong with it!!

[WytWun]

I think the MAF has a hot wire and a reverse biassed diode. There is not a lot to go wrong with it!!

MAFs in the 2nd & 3rd gens are the Karmann Vortex type. They incorporate some electronics, including a pressure sensor and amplifier, to generate a frequency signal from the Karmann vortices created in the body of the MAF.

A build-up of crud on the airflow straightening honeycomb or the various inner surfaces of the MAF body can affect the vortex generation (and therefore distort generation of the frequency signal) and also block the passages to the pressure sensor resulting in no frequency signal output. The electronics also age (particularly certain types of capacitors) resulting in eventual failure.