This is power OK 2400 rpm upwards
approx
.
This is fault present idle to 2400 rpm rpm
Vacuum gauge confirms valve working according to PWM signal.
Carl,
I've got a feeling that we are barking up the wrong tree, I've just scoped the pwm signal to the control solonoid and it seems that on my vehicle it's doing exactly what the ECU is commanding, so I believe its a symptom and not the fault! I think the ECU is misinterpreting the load signal and the main input is I believe the AMM. I've got a Picoscope coming on Thursday and hopefully I can map frequency output from the AMM to prove this, I hope I'm wrong and you're right.
Mark