The engine idle speed mode becomes worse as one drives a vehicle for several years. This is due to ageing of engine and power-train parts. In this case, unstable idle conditions such as engine stall and droop are frequently experienced when the engine gets heavy torque loads due to power steering pump and air conditioning compressor. The objective of this paper is to study on the idle speed control using PID controller under load disturbances. The input of the PID controller is an error of rpm. The output of the PID controller is an ISCV duty cycle. The dSPACE Controller Boards are used to interface with engine. The on-vehicle test is realized using by SIMULINK and BLOCKSETS tools. The real time interface control panel supplied by Control Desk S/W is designed to have good results in engine idle speed control.