its heat soak from the cylinders, when the engine is running the valves open and close, when the throttle is shut i.e stage starts the heat sits in the plenum, thus t
excess heat to the sensor, thus massive ignition retard on stage starts i used to see 80 degs at time if the stages where 12 miles, then off the stage straight into another, its like trying to set off with the handbrake on slightly.
with it before the throttle plate most of the heat is kept in the plenum, away from the sensor.
though we did find we needed to recalibrate a few other settings to compensate for the distance away.
HTH
