e34alex 0 Report post Posted October 25, 2010 (edited) E34 535i 1989 manual M30 engine with flap type Air Flow Meter. Checking the air flow meter from Bentley manual data, it appears that the incoming supply on pin 3 should be 5 volts (measured 4.98), the resistance between pin 1 and 4 (temperature sensor) should be between about 2.1 k ohm and 2.9 k ohm at 20 degrees (measured 2.33 k ohm) and the air flow meter itself should change resistance smoothly as the flap is moved. Unfortunately I couldn't find if the reading should go up or down and what resistance values to expect. Measured values (from rest to flap fully depressed) change as follows: 560 ohm -> 1100 ohm -> 800 ohm to around 300 ohm or less when the flap is fully depressed. Does anyone know what these should be? I'm not even sure if the resistance should increase or decrease as the flap moves from rest to fully open. I'm thinking that the non linear change observed, means that I need a new air flow meter, but I would like to know what the resistance measurements should be. Has anyone repaired one of these? Can they be repaired? Edited October 25, 2010 by e34alex Quote Share this post Link to post Share on other sites
|ncary 0 Report post Posted October 25, 2010 Can't find the picture I'm thinking of to explain this visually, but if you are confused I'll draw one. Jimmy the black top off the unit and underneath you will see a gold arm that runs over a black contact area. What happens is the little contact dots on the arms cut through this black stuff with many k's of car use. Get some needle nose pliers and grab 1 side of the gold U-arm as close as you can to the center of rotation and bend it down, repeat on the other end of the gold Uarm thing. The contact points will now be on a different track, and should have stable resistance! You know what, I'll draw a non-patronising pic Damn studying sucks, look at the time ^ Quote Share this post Link to post Share on other sites
