Mini Cooper workshop manual page 118

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

ENGINEMANAGEMENTSYSTEM-MEMS Heatedoxygensensor Acceleration enrichment Whenthethrottle pedal is depressed the ECM receives a rising voltage from the throttle position sensor and detects a rise in manifold pressure from the manifold absolute pressure sensor. The ECM provides additional fuel by increasing the normal injector pulse width and also provides a small numberofextraadditional pulses on rapid throttle openings. Over-runfuel cut-off TheECMimplementsover-runfuelcut-offwhenthe engine speed is above 1600 rev/min with engine at normal operating temperature and the TP sensor in the closed position, i.e. the vehicle is ’coasting’ with the throttle pedal released. The ECM indexes the IACVopenslightly to increase the air flow through the engine to maintain a constant manifold Themodularenginemanagementsystemoperatesdepression to keep emissions low. aclosed loop emission system to ensure the mostFuel is immediately reinstated if the throttle is efficient level of exhaust gas conversion.opened. If the engine speed drops below 1600 Aheatedoxygensensor(HO2S)fittedin therev/min on over-run, fuel is progressively reinstated. exhaust manifold monitors the exhaust gases. It supplies a small voltage proportional to exhaustOver-speedfuelcut-off oxygen content to the ECM. As the air/fuel mixture weakens, the exhaust oxygen content increases andTopreventdamageathighenginespeedstheECM the voltage to the ECM decreases. If the mixturewill implement fuel cut-off at engine speeds above becomesricher, the oxygen content decreases andapproximately 6500 rev/min; fuel being gradually the voltage to the ECM increases. reinstated as speed falls. Fromthis signal the ECM can determine the air/fuel mixture being delivered to the engine and can adjustIgnition switch off the duration the injectors are open to maintain the ratio necessary for efficient gas conversion by theWhenthestarterswitch is turned off, the ECM will catalyst. keep the main relay energised for approximately 30 TheHO2Shasanintegralheatingelementtoseconds while it drives the idle air control valve to its ensure an efficient operating temperature is quicklypowerdownposition, ready for the next engine start. reached from cold. The electrical supply to theTheECMmonitorstheenginecoolanttemperature heater element is controlled by the ECM via thefor a minimum of 2 minutes after the starter switch is HO2Srelayintherelaymodule. turned off.If the coolant temperature rises above a certain limit, the ECM switches on the radiator fans. OncethefansarerunningtheECMwillnotpower downuntil either the coolant temperature falls below acertain limit or 8 minutes have elapsed since the starter switch was turned off. If the coolant temperature has not risen above the limit after 2 minutes, the ECM will power down. 12 DESCRIPTIONANDOPERATION

owners manual Mini Cooper