MAF speciffics

[Ramblin MAn]

I have two different MAFs, the one that came with the car and did not have the POT for CO adjustment and one I got from ebay which did have the POT.

When I look at the Bently and BMW info on testing the MAF it says that you measure resistance between pins X and Y as you open the vane door and it should be smooth with no jumps.

What both sources are very vague on are what the values should be and most importantly, should the resistance value continually climb all the way to the end of the travel.

While I was unable to get a value that moved in the MAF without the adjusting POT, if I took the cover off and measured the resistance at the vane itself it behaved just like the one with the adjusting POT.

Both of my MAFs rise in resistance to about the half way mark and then decrease.

Can ANYONE tell me with absolute certainty how the MAF is supposed to behave as far as resistance values are concerned? I'm looking for someone who has a known good MAF and has measured the values through the range of vane travel or has speciffic testing info that includes that info.

[Ramblin MAn]

Maybe I'm being too picky.

Would anyone with a properly functioning MAF and a multimeter be willing to check their MAF if I post the instructions from the Bently manual?

[Ramblin MAn]

we're talking 5 minutes.

[GuySchalnat]

I know I opened one and there were electronics in there. So I suspect that the old resistance test, while it may used to have been valid, is no longer meaningful.

If I recall, you have to tap into the lines while the thing is powered up (not that the engine is on, but that the ignition is on or something) and measure voltage as you open the gate. I never actually figured it out because neither one fixed my problem, which turned out to be the usual vacuum leak or something.

If anyone can publish how to do this easily, I'm sure someone (maybe me) will do it for you.

-Guy