Mini Cooper workshop manual page 115

text version of content this owner's manual page from owners manual to the vehicle Mini Cooper, year of production 1961 - 2000:

ENGINEMANAGEMENTSYSTEM-MEMS Idle air control valve Relay module Theidle air control valve (IACV) is mounted on theTherelay module is located in the engine inlet manifold and controlled by the ECM. The IACVcompartmentadjacent to the engine control module. opensapintle valve situated in an air passage in theTherelay module contains the following relays: throttle housing, allowing air to bypass the throttle• Mainrelay-energisedwhentheignitionis disc and flow straight into the inlet manifold.switched on and supplies power to the ECM. • Fuelpumprelay-energisedbytheECMfora BychangingtheamounttheIACVisopentheECMshort period when the ignition is switched on, can control engine idle speed and cold start air flowduring cranking and while the engine is running. requirements by adjusting the flow of air in the• Starter relay - energised by the cranking signal passage. from the ignition switch. • Heatedoxygensensor(HO2S)relay-energised During cold starting the ECM indexes the IACV openby the ECM and supplies current to the heated slightly to provide a level of fast idle, dependent onoxygen sensor element. engine coolant temperature. As the engine warms, fast idle is gradually decreased until normal operating temperature is reached. Purgevalve Theposition of the IACV should be within the rangeThepurgevalveis driven directly from by the ECM. of 20 to 40 steps when the engine is running.WhenthepurgevalveisopeneditallowstheEVAP canister to vent into the engine inlet manifold. The NOTE:AdjustmentoftheIACVonly valve is opened by the ECM for varying periods applies to the ’learnt’ position, not theunder specific engine conditions to avoid degrading actual position at idle, so adjustment isengine performance. not recommended. If the valve is identified as being outside this range it can be adjusted to within range using TestBook. This ensures that the IACV is at the optimum position within its range for providing further movementtocompensateforchangesinengine load or temperature in accordance with signals from the ECM. NOTE:Thepositionofthethrottlediscis preset during manufacture and the throttle position setting screw MUST NOT be adjusted. DESCRIPTIONANDOPERATION 9

owners manual Mini Cooper