Forums 🚥 PiT STOP 🔧 Hyosung Technical Help Inconsistent rpm at idle, stalling + jerky acceleration GT250 EFI 2010 Reply To: Inconsistent rpm at idle, stalling + jerky acceleration GT250 EFI 2010
Some comments regarding the ISC sensor popping out its piston.
In my bike if you turn on the ignition with the ISC out of place the piston also pops out.
From what I have read and my own conclusions this is normal behaviour because it is the ECU trying to calibrate the ISC before each startup.
What seems to be happening is this: the ISC, which is actually a stepper motor, pushes out the piston until it closes out the vent ( when installed of course). As this point the ECU sends out a fixed number of pulses in the opposite direction to open the vent at starting to a certain amount.