Audi-AAN/ADU/ABY installs are usually quite easy and smooth nowadays. Rarely (these are almost always home-modified setups) there are some issues. This is one of those cases.

New Info. Sorry guys i made a silly mistake with my scope. Basicly my pictures of the cam sensor are wrong and are inverted in my pictures! Please look at

I'm sure you need to register to see these pictures. (if one has cookies already set in the browser that might cause confusion).

Right, i had the scope input on the cam sensor connected incorrectly in my first pictures. Instead of ground i was connected to vcc 5 volt, hence the output looking like it was inverted. Here is the new picture. Both the crank pin and cam are on the same scale eg 1 volt/div.

The voltage messured on a stock aby is 30 volt! Mine is only 6. It is true that with 30V signal the signal to noise ratio is better. But it is not the 6 volt itself that is a showstopper, but the relatively large noise compared to the signal.

I get this trigger fault whenever cold and also at 2200 rpm almost exactly. My wife is calling the car "the frog" as it bounces violently during this trigger fault. Its actually shook something loose on the exhaust as it rattles on the ass of the car now.

The new InputTrigger/UltimateMeasurement secondary trigger log (which needs upgrade to experimental/1.1.76 or 1.1.78 firmware, and new VemsTune) captured during frogging would show if the offending crankhome-VR pulse is before or after the correct pulse. Than we could make some filtering attempt in 1.1.79 to filter it in software (it's not easy, because even if the offending pulse is later, it might be sensed first during initial sync in some cases).

Sorry for all this confusion guys! Thanks for your help so far. !!

Inverted measurement, false conclusion:

Motronic is apparently less sensitive on VR-HALL relative position.

Scopeshot of crankhome-VR and HALL:


In any case,

The cam sensor is stock AAN unit. I tried replaceing it with ABY but there was NO difference to performance.

The HALL sensor is at front of heat at cam pully. (Stock audi AAN). The 1-window wheel is mostly metal with small gap (stock AAN)

The VR noise signal (4 evenly spaced noise)

Can i remove this inverter ? I have some electronic skills and am willing to try if showen with a picture what to do. Thanks des

Yes.. Removing the inverter is extremely simple, ~10 minutes.

Image shows how the components should look without the cam-HALL inverter:


Image is from GenBoard/Manual/InputTriggerHardWare

Disassembling+assembling the Motronic-55 device requires a bit skill or patience, appr. 20+20 minutes

Thank you for the cooperation !

If you link your vemscfg actually used accessible from here (so one does not need to register), I can help changing ignout sequence with 2-3 positions and trigger tooth by 9 so the final effect is 2.5*144=360 degrees.