Tab5%20DME%207.2, BMW educational info, Dokumentacja
[ Pobierz całość w formacie PDF ]//-->DME-ME 7.2 ENGINE MANAGEMENT SYSTEMDME - ME 7.2 is the next generation of engine management systems for current and futurepowertrain control. ME 7.2 replaces M5.2.1 for all 8 cylinder engine applications. The “ME”designation identifies the system as “M = Motronic, E = EML.•••••Manufactured by Bosch to BMW specificationsME 7.2 LOCATION IN E-BOX134 pin SKE (standard shell construction) con-trol module located in E boxNew diagnostic communication protocol(KWP2000)Uses break-out box set (P/N 90 88 6 121 300)Integral EML throttle control system- monitors an interior installed PWG- actuates an electric throttle valve (EDK)Integral Cruise control functionality- monitors cruise control requests- monitors brake pedal and clutch switches- carries out throttle control directly via EDKCarries out DSC III torque reduction requests.VANOS controlIntegrated altitude sensorIntegrated temp sensor for monitoring E boxtemperaturesControl of E-box fanOne touch engine start controlOxygen Sensor heatingEngine overrev & Max speedlimitationActive Hall sensor for camshaftposition monitoring32154Single speed secondary air(9 pins) (24 pins) (52 pins)(40 pins) (9 pins)injection systemElectrically heated coolant system thermostat (same function as previous M62 engine)Longlife spark plugsIHKA Auxiliary Fan control••••••••••••••This training manual only covers new or modified input signal components and output con-trol functions. The balance of the ME 7.2 system functions are as per previous engine man-agement systems. Refer to Engine Electronics (ST055) and OBD II (ST060) training coursematerial for detailed functional descriptions.30ME 7.2 I.P.O.31INTEGRAL ELECTRIC THROTTLE SYSTEM (EML)FUNCTIONAL DESCRIPTIONWhen the accelerator pedal is moved, the PWG provides a change in the monitored sig-nals. The ME 7.2 compares the input signal to a programmed map and appropriately acti-vates the EDK motor via proportionally high/low switching circuits. The control module self-checks it’s activation of the EDK motor via the EDK feedback potentiometers.Requirements placed on the Electric Throttle System:••••••32Regulate the calculated intake air load based on PWG input signals and programmedmapping.Control idle air when LL detected with regard to roadspeed as per previous systems.Monitor the driver’s input request for cruise control operation.Automatically position the EDK for accurate cruise control (FGR) operation.Perform all DSC III throttle control interventions.Monitor and carryout max engine and roadspeed cutout.PWG SIGNAL MONITORING & PWG FAILSAFE OPERATION:••As a redundant safety feature the PWG provides two separate signals from two integralpotentiometers (Pot 1 and Pot 2) representing the driver’s request for throttle activation.If the monitored PWG potentiometer signals are not plausible, ME 7.2 will only use thelower of the two signals as the driver’s pedal request input providing failsafe operation.Throttle response will be slower and maximum throttle position will be reduced.When in PWG failsafe operation, ME 7.2 sets the EDK throttle plate and injection timeto idle (LL) whenever the brake pedal is depressed.When the system is in PWG failsafe operation, the instrument cluster matrix display willpost “Engine Emergency Program” and PWG specific fault(s) will be stored in memory.••Refer to page 38 for additional PWG component and signal information.EDK FEEDBACK SIGNAL MONITORING & EDK FAILSAFE OPERATION:•••The EDK provides two separate signals from two integral potentiometers (Pot 1 and Pot2) representing the exact position of the throttle plate.EDK Pot 1 provides the primary throttle plate position feedback. As a redundant safe-ty feature, Pot 2 is continuously cross checked with Pot 1 for signal plausibility.If plausibility errors are detected between Pot 1 and Pot 2, ME 7.2 will calculate theinducted engine air mass (from HFM signal) and only utilize the potentiometer signal thatclosely matches the detected intake air mass.--The ME 7.2 uses the air mass signalling as a “virtual potentiometer” (pot 3) for acomparative source to provide failsafe operation.If ME 7.2 cannot calculate a plausible conclusion from the monitored pots (1 or 2and virtual 3) the EDK motor is switched off and fuel injection cut out is activated(no failsafe operation possible).•The EDK is continuously monitored during all phases of engine operation. It is alsobriefly activated when KL 15 is initially switched on as a “pre-flight check” to verify it’smechanical integrity (no binding, appropriate return spring tension, etc). This is accom-plished by monitoring both the motor control amperage and the reaction speed of theEDK feedback potentiometers. If faults are detected the EDK motor is switched off andfuel injection cut off is activated (no failsafe operation possible). The engine does how-ever continue to run extremely rough at idle speed.When a replacement EDK is installed, the ME 7.2 adapts to the new component(required amperage draw for motor control, feedback pot tolerance differences, etc).This occurs immediately after the next cycle of KL 15 for approximately 30 seconds.During this period of adaptation, the maximum opening of the throttle plate is 25%.33•Refer to page 39 for additional EDK feedback signal information.NEW OR MODIFIED INPUT SIGNALS/COMPONENTSCAMSHAFT POSITION SENSORSLocated on the upper timing case covers, the camshaft position sensors monitor the posi-tion of the camshafts to establish start of ignition firing order, set up sequential fuel injectiontriggering and for accurate camshaft advance-retard (VANOS) timing feedback.Each intake camshaft’s advance-retard angles are adjusted simultaneously yet indepen-dently. For this reason ME 7.2 requires a camshaft position sensor on each cylinder bankfor accurate feedback to monitor the VANOS controlled camshaft positioning.The sensors are provided with operating power from the ECM main relay. The sensors pro-duce a unique asymmetrical square-wave signal representative of the impulse wheel shape.The sensors are new in the fact that they are “active” hall effect sensors. Active hall sen-sors provide:••low signal when a tooth of the camshaft impulse wheel is located in front of the sensorhigh signal when an air gap is present.The active hall sensors supply a signal representative of camshaft position even before theengine is running. The ME 7.2 determines an approximate location of the camshafts posi-tions prior to engine start up optimizing cold start injection (reduced emissions.)34 [ Pobierz całość w formacie PDF ]