Is idle speed adjusted with the kit or with the engine's own idle screw?
Idle speed is always adjusted from the engine's own idle adjustment screw. The GS740 and GS740-3P are actuators that drive the position of the throttle lever; with the potentiometer at its lowest position the cable releases the throttle lever and the engine returns to its own mechanical idle. The kit neither raises nor lowers idle; calibration must also be done after this mechanical idle has been set correctly.
Do not mix up the order: first the engine's mechanical idle, then the kit calibration.
- Idle: adjusted from the idle stop screw on the engine's throttle butterfly or fuel pump. Bring it to the manufacturer's value.
- Cable tension: with the potentiometer at its lowest and the engine at idle, tighten the cable to the throttle lever so it is taut but not pulling the lever. If the cable is pre-tensioned, idle will appear raised.
- Upper limit: on the GS740-3P, run up to maximum speed with the potentiometer and touch the blue wire to GND; after about 8 seconds the upper limit is stored and the potentiometer redistributes the span between idle and this limit as 0%-100%.
If you change the idle screw afterwards, the lower end shifts; on the GS740-3P calibration has to be repeated. On the GS740 the lower end of the potentiometer still corresponds to the engine's mechanical idle; what you store with a long button press is the work speed, not the idle.
Full topic: Electronic speed and throttle control on diesel engines