Simos system idle mode (2.0L engine) (VW Sharan 1)

When the throttle valve is closed, the signal from the throttle position sensor is sent to the ECU, which issues commands to open the electromagnetic valve of the idle speed control valve, installed parallel to the throttle valve and adjusting the amount of the working mixture supplied to the engine. Idle mode is maintained within the range from 660 to 740 min⁻¹.

Idle speed and the amount of CO in the working mixture are regulated electronically and cannot be checked and adjusted without using a fault recorder. Idle speed can be measured using a special tachometer. Adjustment of idle speed should be performed only at a service station if it does not correspond to the norm.

To measure idle speed correctly, follow these guidelines:

• warm up the engine to its operating temperature. It should be at least 80°C;
• turn off all electrical consumers;
• turn off the air conditioner if you have one;
• the exhaust system must be in good working order;
• measure the CO content using a special device. The connection point for the CO measuring device is located next to the throttle body and is built into the intake pipe. The permissible CO content is from 0.3 to 1.2%.