[Richard L]

I cannot say a specific pressure that will work. You can to get a couple of inline needle valves and calibrate it.

I am not much good at mechanical solutions. It requires patience. I don't have an electronic solutions either. Might look into this in the future.

Just to give you can some idea how sensitive this is. The water is drawn into the nozzle by capillary action, aided by the partial vacuum created by the venturi effect of the pressured air running over the water line (black hose).

When I alterd the height of the nozzle relative to the water level, the atomising quality varied a great deal. I carried out this experiment out of curiosity. I modified one of our standard nozzle to be air assisted with some success but the difficult part is getting it to work with consistence. It turned out to be very involved. Something to revisit in another day.

If STFT and WGDC is not conclusive. Individual timing is not available. You are now left monitoring temperature. Perhaps this will give you some useful feedback. What about mis-fire code?