Planning the next
AO Silver Member
Join Date: May 2007
Location: United Kingdom
I looked at this a bit more afterwards and for the P1 there's a very interesting graph in the workshop manual ( Vol 3 pt 2, 1997 model year 29A, page 12 ) of the values presented to the ECU by the MAF for the full range of air flows. What's interesting is that at maximum airflow, the MAF voltage sent to the ECU is 5v. There's also a block diagram of the MAF and this combined with the graph leads me to think that the P1 MAF actually operates at 5v by way of a voltage regulator integrated with it.
From that, I suspect that the P2 operates in a similar way and a test of pin 5 would show about 5v with the throttle wide open and around 1v or less at idle.
That combined with other data ( current across the MAF at different airflows ) would allow a MAF to be bench tested.