[tmoss]

Why?

The spout suppplys the rpm signal back to the EEC to use in varying the timing - who knows what happens without this input, but you are bound to get detonation somewhere in the rpm versus load spectrum without it. Why run without the spout?

 

[tmoss]

OK

So your getting detonation with the spout in the circuit. Have you checked any other componants like EGR valve-actuator-EEC position sensor, ACT (air temp), ECT (eng temp), TPS (throttle position), etc.? These sensors also play into where the EEC decides to set timing.

You should not detonate with the spout in unless there is a problem somewhere else.