Update - car was converted to 1.0.78fw (similar to an old install I did with the same hall sensor/4 window dist. trigger wheel set-up) and the rpm input is working correctly now.

The car will be tuned after a fuel injector problem is fixed.

VW 4 cylinder engine with distributor.

Hall Effect sensor with 4 window wheel in distributor used for triggering.

Distributor used for ignition, Stepper A to single Ignitior/Coil.

The issue is: RPM value drops very low every few seconds. Does it also misfire / bog than ? Or apparently runs fine ?

Tried using 5volt and 12volt supply for the Hall Sensor, same results.


  • The car is far away from my location. I will get to see it in a week or so. My scope is broken so diagnosis will be difficult.
  • Tried setting the trigger teeth to "4" (incorrect) instead of "2" and the car started/idled, but dies when the throttle is hit.
  • Why would 4 teeth setting run better? (Distributor with 4 windows, turns half speed so one engine rev = 2 trigger edges, not 4.)