[beetos]

So rather than bang my head against a wall, I decided to remove the MPS links, and go back to straight IDC with a 1:1 preamp, and running the system off a PWM map within my ECU made up of RPMxMAP. The PWM output is connected to the green wire on the gray harness, and it works perfectly.

I tested it by temporarily mapping a potentiometer to give 0-100% PWM spaying the injectors out of the manifold, and it works great, this allowed fine tuning of the threshold / scale / fails safe limits etc 'on the fly'.

I'm still curious why my P&H set up never worked running off the injectors though.