Ecumaster forum

I'm trying to use a distributor with an optical sensor as a secondary trigger.
I've left only one of four tabs on the rotor, so I have single tooth cam signal.

The problem is that the voltage difference between ontooth and offtooth is only 0.5V. It goes from 0.2V to 0.7V.
The ECU doesn't pick up the tooth, so I have no secondary trigger.

I've tried with and without the pullup to 5V.

How do I increase the sensitivity or lower the trigger voltage?
Thank you

are you sure its connected and working correctly??

i think it would be very unlikely for any oem system to use such low voltage differentials it would be far to susceptible to interference etc.

I was checking it on an oscilloscope. Tried swapping wires.. Sensible signal was only when it was connected like it's now.
It's a Ford Pinto 2.0 engine and was EFI from factory 1987

RHD wrote:are you sure its connected and working correctly??

i think it would be very unlikely for any oem system to use such low voltage differentials it would be far to susceptible to interference etc.

Optical sensors in most cases are open collector ones.
So you need to use pullup. Try if the pullup is working... Or maybe lower pullup is required


One more thing. The optical sensor requires power (in most cases +12V but check in your car wiring diagram)

Yes I have it connected to 5V. Tried 12V also, but the signal voltage was exactly the same.
I'll try playing with the pullup. Thanks

When I enabled the pullup the voltage difference was even smaller. It went from 0.6 to 0.7V.
But I was swapping wires to try all possible connections and I killed the sensor

I'll try different type of distributor.