AFM testing procedure and specs?

[DaN]

I am just curious about the correct way to test the AFM in my 85 325e. I only have access to a fluke digital multimeter, is it possible to correctly diagnose one of these with just a meter?

Also when I checked before, I was getting a 5v reference signal to the temp sensor, and a 10v reference signal to the AFM part. Is this correct? I have never seen something that used a 10v reference.

Does someone have a writeup and a list of specs for this particular sensor?

Also, would the AFM have to be re-calibrated after a raise in compression?
After doing a head gasket job, and shaving the head .020", the car has idled terribly.
Kind of rough, like a misfire, but everything on it is new, and there is no power problem off idle. Could the increased compression/vacuum put the AFM out of calibration?

Any input would be appreciated, thanks.

[DaN]

No one knows anything about this? or a place where I can find this info? :shock:

[ColdAccord]

dan i'm about to scoop an afm from gp and 2 towels from ubrf. his roommate is junking his e30. the whole car is fucked though, even the bottlecaps are bent. you can snag that next time you come up to buffalo if you want it

[DaN]

dan i'm about to scoop an afm from gp and 2 towels from ubrf. his roommate is junking his e30. the whole car is fucked though, even the bottlecaps are bent. you can snag that next time you come up to buffalo if you want it

What model is it?
Who is this "gp" you speak of? If you are getting the afm, how will I get one too?
Does he have decent seats in it?
How are the fenders?

[bmwguru007]

It doesn't look like you can test it with a multimeter. According to Bentley, "no electrical test specifications are available for the air flow sensor installed on the 6-cylinder models". So really the only test would be to swap yours out with a known good one to see if it fixes whatever problem you're having. What makes you suspect the AFM in the first place?

[peerless]

afm testing

ok, actually you can do a basic test on it. You will need to check pins 7 and 9 at the ECM for variable resistance as someone moves the AFM door.

Refer to page 48 of your Bentley Manual. If you don't have one, get one.

Ecm is located above the glove box you will need to backprobe the wires mentioned.
You can use sewing needles to probe into the connection, clip your leads, check for variable resistance. The slower you move the door the more accurate results you will get. A scope is more suited to this so you can see the graph and watch for glitchs you will probally not see with just numbers. Good Luck.

Robert

85' 325e