I have two 74 1.8 pars cars (I know, its a sickness) both cars are beyond running, but the air flow sensor looks to be in great shape. I would like to verify that they are working and other than installing them on a running 1.8 how can I test them?

yes I plan to sell them, but I don't want to sell non working parts.

Thanks

most every time they just mechanically fail with the flap sticks. Make sure that you test it hot after it expands as the flap may not stick cold but may hot.

It must send a voltage signal based upon flapper location.
First, Like the Doctor says, make sure the flapper works.
Then, look for the pinout (check the L-Jet site in 914Info at top of page)

Feed it with the right voltage on the right pin, it should provide a scale of voltage as the result.

Rich

Inside the AFM there is a fixed resistance, a variable resistance and a switch. With an ohm meter and a diagram these components can be tested. The switch should close when the flap is opened slightly and the resistance should vary smoothly. The Dr. pointed out the common mechanical failure. On the electrical side the usual failure is wear of the wiper components causing bucking or flat spots. If the black cover has been removed someone may have tried adjusting it and it may never be right again.