I am a little confused on my test result of my AFM.

I am using page 4B-60 in the FSM

On test #4 I connected E2 to Vs and although my fully open and fully closed were within spec. I couldn't help but noticing that as I opened it up it went from around 200 to 600 to 200 to 600 to 80. I had assumed that the AFM would be linear. Which is bad my thinking or my AFM?

 

What you saw is normal as can be. Not linear.

 

How does the ECU know how far open the flapper is if the resistance doesn't build up? What we saw could best be described as oscillating.

I am confused how the ECU would know how much air is being taken in if the resistance appears to be random with respect to how far open the flapper is.

 

bump

 

If you'll probe the output Voltage of the AFM to the ECU, you'll find the voltage changes more or less in a liner fashion. Like starts at 1vdc and works it's way up to the max potential which would be somewhere around 5vdc.

All plugs must be connected to do that. You'd backprobe the afm output wire to the the ECU at the ECU. Pin 2E a green/blue wire.

EDIT: Actually the voltage starts high and works its way down as the vane move aft, not as I described above. Starts around four vdc and works its way down to one or less.