Unstable engine speed M142

[heavydiesel]

I have an M142 on a Cummins ISX diesel engine and I cannot seem to get a stable reading of engine speed. It is much noisier than I would call satisfactory and it is impacting fueling, timing, etc - any table that is a function of engine speed. I have done an input capture and the signals look great. I've attached input capture and a log where you can watch engine speed and fuel mass fluctuate. The engine is being held at a constant 800 RPM.

I have noticed that engine speed and engine speed reference instantaneous both seem to read the same thing, which seems odd. Which one is used for pulling from tables? Is there a way to filter engine speed reference instantaneous to feed engine speed?

I am using the 'Scania SGL12A' Reference mode. Falling edge for both cam and crank active edge. I have tried changing threshold voltages, hysteresis, pitch threshold's etc to try and get a more stable reading with no success.

Some help would be appreciated, thank you

[Stephen Dean]

Hi,

Try this file. The Diesel Packages require an Ignition output to be allocated to have a smoothed Engine Speed calculation.

[heavydiesel]

Thank you. I will try that. Please check PM