2.5 16v stalling




Let me know how things measure with the AFM potentiometer after you are back to normal.
When you are done with all the AFM pot issue, we need to address your economy gauge as well. On a manual transmission that gauge needs to be pegged all the way to the left at anything over 700rpm with AC turned off and no heavy load on the Alternator (like aux fans running). If you have a working calibrated gauge that is 17inch-mercury of vacuum. I calibrated mine. Mine is pegged, and has always been accept in one occasion that I fixed. Let us not deal with that now, as we have bigger fish to fry and again, let's fix one problem at a time.
- Cheers!
1 meeting yesterday was like a gremlin hit by water. Tuned into 4 meetings. Thankfully much got sorted out. 12-7 I couldn't eat. I was done by the time I got home. Had a beer and zoned out. I should get to it this evening time permitting.
The pedal box and front hydraulics are done next find or rebuilt the water pump. I already have the timing belt and tensioner.
Then the fuel system and properly clutch.
And one of the arms which touch the AFM was bent.
I got the following measurements
Ignition on
6-2=12.08
3-2=3.67
Cold idle
6-2=13.76
3-2= 8.28
Then it stalled an wouldn't restart.
It started doing the same thing. The sensor plate would go down at start then pop up and the engine stalls. If I adjust the throttle too tight to keep it open it would idle but it wouldn't rev and would stall.




#49. With the bent contactors of the AFM plate lever replacing the AFM pot would be futile.
Mercedes only sells the entire AFM assembly (with the AFM pot on it) for good reason. It assures the contactors are not in bad shape.
Unfortunately that assembly costs $500. AFM pot is $200.
But Before jumping to conclusions first take the measurements asked in #49 so we know what is going on from a far.
- Cheers!
The Best of Mercedes & AMG




(1) And are there any discontinuities in the readings as you sweep?
(2) Please also measure resistance from pin 3 to pin 1 on the AFM pot. And during the sweep that should not change at all.




(1) And are there any discontinuities in the readings as you sweep?
(2) Please also measure resistance from pin 3 to pin 1 on the AFM pot. And during the sweep that should not change at all.




You are measuring these with AFM pot unplugged right?
Are something is wrong with your meter.
I was expecting an open or a short but that is not the case.
It is possible there is something wrong with your wiring to the ECU or the ECU itself








You need to first diagnose and fix the AFM pot issue.
Unplug the ECU and repeat those measurements (between pins 1-2-3 of the AFM pot) on the ECU side to vindicate the wiring.
Make sure your meter is not uncalibrated somehow as well by measuring a known resistance (in the car our elsewhere)
Like I said previously your resistances are half of what they should be. Never heard of that before unless something went wrong with your measurements or the meter is busted.
At the afm pot 1-3=1839 some change when swiping but at wot the same.
1-2=1
Gradual increase while swiping then 0 from halfway




1-3=1839 ohms is not the right value.
Gradual increase for 1-2 is also not correct as it should go form ~1.5K ohm to almost 10.0K ohms during the sweep.
Unless you can converge on what is going on with the AFM pot you will not get very far in fixing your issues.



