AFM testing

[Gavin Waddell 18]

Following on from my car cuts out thread owned to test my AFM, I found the Porsche 944 topic, when looking through it it doesn’t really explain the 9v battery method. Also the AFM that they use only has 4 pins and the numbers aren’t the same as mine. Has any one done this and could point me in the right direction. 

 

Thanks gavin 

[SRDT 182]

Do you have a XU9JAZ engine?

If so your AFM is a Motronic one with 5 pins:

 

 

[Gavin Waddell 18]

Ok thanks for that should help nicely

[Gavin Waddell 18]

Ok soi  heckled my AFM using tje obove guide. I got some weird values.

 

for the first test between 5-7  flap closed I got 113 ohms

 

2: not a smooth transition ohm meter jumps about.

just before the flap is fully open I get 950ohms but not very stable fluctuates sometimes dropping into the 800’s then when the flap is fully open the AFM drops to 450 ohms.

 

So not really within the tolerances indicated.

 

is my AFM kaput?

 

Thanks Gavin 

[DamirGTI 342]

Analogue multimeter is much better for doing this test ... as you can clearly see if the needle sticks/judders/jumps , digital multimeters is numbers + it's too fast for such testing purpose .

 

Since you have a Motronic AFM , you can't really see the entire carbon track with the plastic housing on top of it ... unscrew and remove the plastics and inspect the track visually (shine some light with an flashlight on the track or take it out and inspect in the sun light) ..

 

D

Edited April 11, 2020 by DamirGTI

[Gavin Waddell 18]

I took the cover off and I repacked the AFM already. So when I did I the check I was locking at the pointer on the track. What do you think

[DamirGTI 342]

That's the Jetronic AFM , looks good from what i can tell from the picture .

 

Which engine do you have ? 

Jetronic AFM wont work on Motronic car and vice verse . 

 

D

 

Edited April 11, 2020 by DamirGTI

[Gavin Waddell 18]

Yeah sorry forgot to mention that I used the jetronic method.  It’s the original AFM from when i bought the car. My just trying to follow on from my other thread about car just cutting out. So checking components. And as I had the weird problem of it being able to run without an AFM I thought I would check it.

 

back to the framing board then.And thanks Damir

[Zetec7 4]

Hi Gavin, I have no fault with my AFM that I know of but decided to have a look inside while it was off during  a rebuild.and have the same as you.

I came across this article on Bosch Fuel Injection which  may  help.

A number of AFM have a variable resistance which initially  would appear to be incorrect.  The change in resistance will increase and decrease a number of times from closed to open. This type of resistance is used to make the output compatible  with the operation of the ECU.  For the purposes of this of this book it is not necessary to explane+++++++++++++++++ but this type of reading is normal on some types.

hope that helps