I have a question about testing the AFM and resistance readings on the flap. All things tested good on both per the FSM. However, I assume the sweep on the flap should be even and steady as I move the flap from full open to partially closed. Both AFM that I have behave similarly. Both are not even and steady. Is this normal?

 

Do you mean how your values jump/skip as it increase? Rather than increase smoother like 250 251 252 253 254.... ?

I believe that is a result of using a digital meter. If you use an analog meter (with a needle) it'll be easier to see. With an analog meter, the needle will jump like crazy if there is a dead spot / fault.

See at 0:25 the needle jumps like crazy. Also at 0:52 on the way back down.

With a digital meter it's a little harder to see. You can move the flap really slowly, and make sure the readings don't do anything unexpected.

Example: 250->300->350->800->400->450 You might have a bad spot at the position where it's reading 800.
OR
Meter will keep jumping around even if flap head steady position.


From your video, it looks fine to me

 

Thanks for the help. I have to old needle type meters in my tool box. I will put a battery in and test it out.

I noticed to jumping when steady too.

I did find a thread where this type of issue was brought up but no answers.

 

I tested with a needle meter. This is the sweep from closed to open. No jumps just dips and recovery. I think it's no good


From the looks of your video the part inside the AFM is just a standard POT with an additional trim pot to bring the pot to designed specifications. As pots are manufactured within a tolerance. Just a one percent difference might not quite be accurate enough. I know how to test a standard pot. I just thought that is was possible to have a custom pot taper in there.

My other AFM tested bad too. The funny thing is, it was replaced or repaired at some point because I see that it was cracked open and silicone sealed. The section that is screwed together was partially loose. You can see where the air had squeezed through over time as it was dirty in that spot.
That car always ran really well, I am a bit shocked.

I can get a used one locally with a discount. I will order one and test it at the store. I will report back later.

Thank you again for your time!

 

O interesting. Much easier to see on an analog meter. I need to get me one lol.

Which pins are you measuring between?

 

I believe it was E2 and VS.

Edit: I forgot to mention, this is from an S4?

 

Yes, above is for S4.
Page 4A-54 in the fsm

 

I did some reading and the sweep readings from the AFM at ES to V2 is not supposed to be linear. What is linear is the voltage reading sent to the ECU.