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Related Manuals for Mercedes-Benz M 447 hLAG
Summary of Contents for Mercedes-Benz M 447 hLAG
- Page 1 Service MERCEDES-Benz ___________________________________________________________________ Natural Gas Engine: M 447 hLAG In Mercedes-Benz City Bus Click bus for index engine control unit Mercedes-Benz AG • Omnibus Product Division • Status September 2003 (EvoBus-Service / AFT)
- Page 2 Mercedes-Benz omnibuses with a natural-gas power plant (M 447 hLAG). In the contents we provide information on the working and operating modes of the engine control unit (MR) EGM (electronic gas engine) of the M 447 hLAG. Details are based on the software version 14B_001 ZCRB0A01 The specified part number serve only mark marking and distinguishing individual components.
- Page 3 Abbreviations _____________________________________________________________________ °DK Grad DrosselKlappe (Degrees of Throttle Valve) AntiBlockierSystem – Traction Control (Antilock Braking System) Automatisches Getriebe Nutzfahrzeug (Automatic Transmission for Commercial Vehicle) AbgasTurboLader (Exhaust-Gas Turbocharger) ATLR AbgasTurboLaderRegler (Exhaust-Gas Turbocharger Controller) Brems-Steuerung (Braking Control) Controller Area Network Compressed Natural Gas (primarily methane) DrosselKlappe (Throttle Valve) DrosselKlappenSteller (Throttle Valve Actuator) DRehzahlBegrenzung (Speed Limitation)
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Page 4: Table Of Contents
Table of Contents _____________________ To forward directly to relevant section, click on BOLD sections headings Natural Gas Engine M 447 hLAG Functional Description of EGM Introduction Torque control 2.2.1 Engine protection functions 2.2.2 Idling control Engine state detection Cylinder filling 2.4.1... - Page 5 Engine cannot be switched off 5.1.3 Increased engine idling speed 5.1.4 Reduced engine output 5.1.5 Rough engine running, traction interruption Special tools Circuit diagram of M 447 hLAG Engine performance data Status September 2003 (EvoBus-Service / AFT) Page: 5 of 83...
- Page 6 Table of Contents _____________________________________________________________________ Safety precautions when working on EGM Appendix Pulse width modulated signal Overview of bus systems (EvoBus) Index Status September 2003 (EvoBus-Service / AFT) Page: 6 of 83...
- Page 7 Characteristic curve: Oil pressure sensor....................65 Performance graph for O 447 hLAG, 240 kW ................... 78 Performance graph for M 447 hLAG, 185 kW ..................78 Drawing: pulse width modulated signal ....................80 Overview of bus systems (EvoBus) ......................81...
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Page 8: Natural Gas Engine M 447 Hlag
_____________________________________________________________________ 1 Natural Gas Engine M 447 hLAG The M 447 hLAG is a further development of the M 447 hG and is used in the natural gas Citaro from Mercedes-Benz and in the CBC chassis. Technical data of engine: •... - Page 9 The M 447 hLAG Natural-Gas Engine _____________________________________________________________________ The M 447 hLAG is a turbocharged engine. The turbocharger is a rigid-geometry turbocharger with a wastegate. The charge air pressure is controlled for the respective operating point by the EGM. For this purpose the EGM actuates the electropneumatic converter (EPW) of the wastegate.
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Page 10: Overall System Of Natural Gas Engine
The M 447 hLAG Natural-Gas Engine _____________________________________________________________________ Overall system of natural gas engine Pressure control valve Mixer Charge-air temperature Charge-air pressure Gas temperatur Gas pressure CNG ~8 bar Heat exchanger Engine coolant Status September 2003 (EvoBus-Service / AFT) Page: 10 of 83... -
Page 11: Functional Description Of Egm
The EGM (electric gas engine) engine control unit is mounted on the engine, and is therefore part of the engine. Only one basic control unit is required for all offered output variants of the M 447 hLAG. The EGM is adapted to the corresponding output and engine variant with different programming. An EGM that is already programmed is considered a special engine component and may not be interchanged between different engines. -
Page 12: Basic Egm Functions
Functional Description of EGM _____________________________________________________________________ Basic EGM functions Status September 2003 (EvoBus-Service / AFT) Page: 12 of 83... -
Page 13: Torque Control
Functional Description of EGM _____________________________________________________________________ Torque control Like the PLD, the EGM is a torque-based engine control unit. The EGM receives the torque specification from the FR via a CAN bus. The torque specification refers to the engine output shaft and corresponds to the torque requested by the driver (interpretation of the accelerator pedal position by the FR). -
Page 14: Engine Protection Functions
Functional Description of EGM _____________________________________________________________________ 2.2.1 Engine protection functions Several functions for protecting the engine under unfavourable engine operating conditions (high coolant temperature, high charge-air temperature etc.) and in case of errors in the sensor technology, actuators or mechanical systems are implemented in the EGM engine control unit. These can result in the possible torque at full load being limited by the engine protection functions. -
Page 15: Engine Protection: Charge-Air Temperature
Functional Description of EGM _____________________________________________________________________ To protect the catalyst at excessively high exhaust-gas temperatures, the available engine torque is limited as a function of the engine speed and exhaust-gas temperature according to the catalyst and engine speed. 2.2.1.1 Engine protection: charge-air temperature The engine protection function charge-air temperature is intended to reduce the maximum permissible engine torque at excessively high charge-air temperatures. -
Page 16: Engine Protection: Coolant Temperature
Functional Description of EGM _____________________________________________________________________ 2.2.1.2 Engine protection: coolant temperature The engine protection function coolant temperature is used to protect the engine against operation at impermissibly high coolant temperatures. This function consists of two parts which are processed independently of the engine state. •... -
Page 17: Engine Protection: Turbocharger Overpressure
Functional Description of EGM _____________________________________________________________________ 2.2.1.3 Engine protection: turbocharger overpressure The engine protection function turbocharger overpressure is used to protect the engine during operation against impermissibly high boost pressures ("turbocharger overpressure"), e.g. in case of a defective "wastegate". • Turbocharger overpressure detection If the actual boost pressure is above the permissible value of 2.35 bar for longer than 15 seconds, then the event "Boost pressure too high"... -
Page 18: Engine Protection: Boost-Pressure Substitute Value Formation
Functional Description of EGM _____________________________________________________________________ 2.2.1.4 Engine protection: boost-pressure substitute value formation The boost-pressure signal is the most important information of the EGM and the condition for realising correct operation of the natural gas engine. From the boost-pressure signal the EGM determines the air mass present in the combustion chambers. -
Page 19: Engine Protection: Crankshaft Emergency-Running Mode (Dual Ignition)
M 447 hLAG is equipped with two inductive speed sensors – one crankshaft sensor and one camshaft sensor. Both speed sensors are evaluated and monitored by the engine control. As the resolution of the crankshaft sensor is higher than that of the camshaft sensor (more tooth faces on the crankshaft gear), the crankshaft signal is normally used for determining the crank angle. - Page 20 M 447 hLAG is equipped with two inductive speed sensors – one crankshaft sensor and one camshaft sensor. Both speed sensors are evaluated and monitored by the engine control. As the resolution of the crankshaft sensor is higher than that of the camshaft sensor (more tooth faces on the crankshaft gear), this sensor is normally used for determining the crank angle.
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Page 21: Engine Protection: Lambda Lean-Controller Probe
Functional Description of EGM _____________________________________________________________________ 2.2.1.7 Engine protection: lambda lean-controller probe The engine protection function lambda lean-controller probe is intended to reduce the maximum permissible engine torque if the lambda correction factor differs too greatly and/or in the case of an implausible probe heating current. -
Page 22: Engine Protection: Gas Injection
Functional Description of EGM _____________________________________________________________________ 2.2.1.8 Engine protection: gas injection From the software version 13A, the EGM engine control unit is capable of detecting fault states on the gas injectors and their wiring. In the case of a fault, corresponding fault codes are stored in the fault memory and emergency running measures are initiated. -
Page 23: Engine Protection: Ignition
Functional Description of EGM _____________________________________________________________________ 2.2.1.9 Engine protection: ignition From the software version 13A, the EGM engine control unit is capable of detecting breaks in wiring on the primary side and interturn faults on the actuation cables of the ignition modules. In the case of a fault, the corresponding fault codes are stored in the fault memory and corresponding emergency running measures are initiated. -
Page 24: Engine Protection: Oil Pressure Pre-Warning Threshold
Functional Description of EGM _____________________________________________________________________ 2.2.1.10 Engine protection: oil pressure With the engine protection function oil pressure it is currently possible to display a two-stage warning concept. The engine protection function is calculated every 10 ms in the engine-on mode with insufficient oil pressure, and in the other states ("Engine stopped", Start") the function is reset. -
Page 25: Engine Protection: Oil-Pressure Warning Threshold
Functional Description of EGM _____________________________________________________________________ Engine protection: oil-pressure warning threshold MTS - Oil-pressure warning threshold Oil pressure threshold [bar] = f(Speed [rpm]) Speed 2.2.1.11 Engine protection: overspeed To protect the engine against operation at an impermissibly high speed ("overspeed"), an overspeed protection function is implemented in the control unit. - Page 26 Functional Description of EGM _____________________________________________________________________ Engine protection: exhaust-gas temperature Torque limitation Exhaust-gas temperature Exhaust-gas temperature Exhaust-gas temperature Limitation torque Engine speed MOB - Torque limiation with exhaust-gas temperature Max. torque [Nm] = f(E. gas temp.[°C], Speed [rpm]) Max. torque [Nm] Speed [rpm] Exhaust-gas temperature [°C] Status September 2003 (EvoBus-Service / AFT)
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Page 27: Idling Control
(e.g. when starting off at traffic lights, switching on the air conditioner etc.) and slow adjustment of the target idling speed compared to the diesel engine are typical for the M 447 hLAG and normal. Poor, rough idling frequently indicates problems in the ignition system. An increased idling speed frequently indicates the entrance of unmetered air, which the engine draws past the throttle valve. -
Page 28: Engine State Detection
Functional Description of EGM _____________________________________________________________________ Engine state detection The engine state detection is a central part of the EGM torque control. The engine state detection is used to determine the current engine state This is checked every 10 ms. Based on the determined engine state, the related functions for calculating the target torque, and with it all other variables, are then worked through. -
Page 29: Throttle Valve Control
2.4.1 Throttle valve control The throttle valve of the M 447 hLAG is positioned by an electric throttle valve actuator (DKS from Woodward). The throttle valve actuator has its own integrated power and control electronics. The throttle valve, electrical throttle valve actuator and the electronics form a unit. The throttle valve actuator is supplied with power from the vehicle (not by the EGM). -
Page 30: Throttle Valve Diagnosis
Functional Description of EGM _____________________________________________________________________ 2.4.2 Throttle valve diagnosis The position feedback sent by the throttle valve actuator to the EGM is an analogue signal in the range from approx. 0.3 V to 4.7 V. Due to the low accuracy of the EGM, the analogue signal "throttle-valve actual position"... -
Page 31: Turbocharger Control
2.4.3 Turbocharger control The M 447 hLAG is equipped with a water-cooled rigid-geometry turbocharger. Output control is realised with a wastegate. The wastegate is actuated by a pneumatic actuator. If the pneumatic actuator is not charged with pressure, then the wastegate is closed. -
Page 32: Switch-On Conditions For Boost-Pressure Control
Functional Description of EGM _____________________________________________________________________ Switch-on conditions for boost-pressure control Switch-on conditions Target boost pressure > & ATL controller ON B.-press. threshold ATL onn Characteristic curve Engine speed > Speed threshold ATL on Switch-off conditions Fault memory entry 1415 Fault memory entry 1416 Target boost pressure <... -
Page 33: Switch-On Threshold For Boost-Pressure Control
Functional Description of EGM _____________________________________________________________________ Switch-on threshold for boost-pressure control DK - Boost-pressure threshold ATL on Target b.-press. [bar] = f(speed [rpm] ) Speed Switch-off threshold for boost-pressure control DK - Boost-pressure threshold ATL off Target b.-press. [bar] = f(speed [rpm] ) Speed Status September 2003 (EvoBus-Service / AFT) Page: 33 of 83... -
Page 34: Turbocharger Diagnosis
Functional Description of EGM _____________________________________________________________________ 2.4.4 Turbocharger diagnosis By comparing the target boost pressure and the actually measured boost pressure, the EGM can deduce that there are malfunctions in the turbocharger circuit. Two monitoring functions are realised in the EGM. •... -
Page 35: Gas Injection
Functional Description of EGM _____________________________________________________________________ Gas injection The fuel (here CNG) is injected by cylinder-selective actuation of the gas injectors following successful crankshaft/camshaft synchronisation. The injectors are actuated in two phases. In the first phase, the so- called push phase, the injectors are heavily charged with current to open them quickly and completely. The push phase follows the hold phase in which the injectors are charged with less current to protect them from overheating. -
Page 36: Overview: Gas Mass Calculation In Normal Operation
Functional Description of EGM _____________________________________________________________________ Overview: gas mass calculation in normal operation Air mass Air mass g/stroke Mass ratio Gas mass Fault in lambda control (uncorrected) [g/stroke] Limitation Basic Basic adjustment factor Warm-up Warm-up correction factor Basic adjustment MIN limitation (lambda) Basic adjustment MAX limitation (lambda) Basic adjustment if fault in lambda control Lambda-... -
Page 37: Lambda Control
2.5.3 Lambda control The M 447 hLAG is a lean engine with lambda control. The lambda controller integrated in the EGM is responsible for compliance with the pre-programmed target lambda in all engine operating points. During idling the target lambda is equivalent to approx. 1.2, however is changed by the EGM in dependence on the control deviation by up to ±... -
Page 38: Lambda Control Diagnosis
2.5.5 Overrun fuel cut-off (SAS) The overrun fuel cut-off (SAS) of the M 447 hLAG is realised in the EGM. The overrun fuel cut-off is a function of the target engine torque (FR), engine speed and vehicle speed. The overrun fuel cut-off process is divided into the sub-processes SAS_soft (soft overrun fuel cut-off) and SAS_hard (hard overrun fuel cut-off). -
Page 39: Release Of Gas Injection And Actuation Of Gas Cut-Off Valve
Functional Description of EGM _____________________________________________________________________ Release of gas injection and actuation of gas cut-off valve Status September 2003 (EvoBus-Service / AFT) Page: 39 of 83... -
Page 40: Ignition
Functional Description of EGM _____________________________________________________________________ Ignition The ignition is carried out as cylinder-selective ignition. The ignition is triggered as soon as the system is synchronised. The procedure for calculating the ignition angle differs considerably from the engine state. There is a special calculating specification for determining the firing angle in the engine state: Starting, a different one in the idling mode and another in the partial and full-load operating modes. -
Page 41: Function Overview Of Firing Angle Calculation
Functional Description of EGM _____________________________________________________________________ Function overview of firing angle calculation Status September 2003 (EvoBus-Service / AFT) Page: 41 of 83... -
Page 42: Electrical Description Of Egm
Electrical Description of EGM 3 Electrical Description of EGM System interface overview 3.1.1 Block diagram Block diagram for electrical description: Motorstecker (55-polig) Service switch Start/Stop Hand-held + monitor and printer tester Sensors COM 1 ignition Level converter Throttle valve Proportional valves Gas injectors wire Crankshaft/camshaft sensors... -
Page 43: Connector Assignment Of Egm And Ignition Modules
Electrical Description of EGM 3.1.2 Connector assignment of EGM and ignition modules Control unit: Male connector, 55-pin ( engine connector ) Pin No. Assignment or Designation On/Off Lambda lean probe IP TDC Cylinder 1 sensor ( - ) Crank-angle position sensor ( - ) Injector F Injector E Injector D... - Page 44 Electrical Description of EGM Control unit: Male connector, 55-pin ( engine connector ) Pin No. Assignment or Designation On/Off Proportional valve 1 (low-side) Proportional valve 2 (low-side) Ignition 4 Ignition 6 Proportional valve 3 * (low-side) Throttle valve (-) * : Signal also on vehicle connector Control unit: male connector, 16-pin ( vehicle connector ) Pin No.
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Page 45: Power Supply Of Egm
Electrical Description of EGM 3.1.3 Power supply of EGM 1. Supply voltage Nominal voltage: 22 V < U < 30 V Undervoltage: 8 V < U < 22 V limited operating range Overvoltage switch-off: U > 32 V 2. Reverse voltage protection, overvoltage protection Reverse voltage protection: continuous polarity reversal... -
Page 46: Power Supply Of Ignition Module
Electrical Description of EGM 3.1.4 Power supply of ignition module 1. Supply voltage Nominal voltage: 9 V < U < 30 V 2. Reverse voltage protection (with connector coding) Ignition electronics Continuous polarity reversal of supply connections without damage. Ignition transformer In case of polarity reversal of supply connections, short-circuit current flows through ignition transformer. -
Page 47: Sensor Technology
In modern throttle devices the actuator, throttle valve and throttle valve sensor are integrated in one housing. In the throttle device of the M 447 hLAG a potentiometer is used as a throttle valve sensor. This is supplied by the internal electronics of the throttle device. -
Page 48: Passive Sensors
Electrical Description of EGM 3.2.3 Passive sensors Requirement: Temperature sensors based on NTC resistors are used as passive sensors. The voltage drop at the sensor resistor, which is supplied with current by a pull-up resistor, is used for evaluation. These inputs are short- circuit-proof and diagnosable like the active inputs. -
Page 49: Digital Inputs
Electrical Description of EGM 3.2.3.2 Camshaft/crankshaft position (inductive) To detect and evaluate the current crank angle and speed of the engine, one inductive sensor (e.g. VDO) each is used to generate the camshaft and crankshaft signals. Inductive sensor data: R in Ω L in mH ±15 % 1000..1385... -
Page 50: Actuator Technology
Electrical Description of EGM Hardware description: The contact current when a button is pressed is approx. 10 mA. In addition, the inputs to the buttons are short-circuit-proof to earth and insensitive to dirt resistances parallel to the buttons. The dirt resistances can have values down to 10 KΩ. -
Page 51: Actuation Phases And Current Curve Of Gas Injectors
Electrical Description of EGM 3.4.2.1 Principle of gas injector actuation Actuation takes place according to the peak and hold principle with subsequent rapid current switch-off. The actuation phases and the valve current curve are shown in the following illustration. Actuation phases and current curve of gas injectors Actuation phases of gas injectors PWM 5kHz U(t) -
Page 52: Proportional Valve Actuation
EGM-C1 sample. The valve current is controlled by means of PWM with intelligent low-side drivers with a diagnostic function, however without current measurement. On the M 447 hLAG only the output Prop 1 boost pressure control is currently used. Data for Prop 1: Valve current:... -
Page 53: Principle Of Ignition Actuation
Electrical Description of EGM The ignition transformer is energised on the primary side when the level changes from low to high on the input of the ignition output stage. The duration of the high phase (closing angle) is map-controlled and determines the peak value of the primary current. -
Page 54: Diagnosis
Diagnose 4 Diagnosis Reading measured values The following table contains the measured values available for Customer Service via Star diagnosis and via the on-board diagnosis. Process Variable Resolution Unit Target engine torque (FR) 1.00 Maximum current engine torque 1.00 Actual engine torque (MR) 1.00 Gas injection angle (Cylinder 1) 0.10... -
Page 55: Target Engine Torque (Fr)
Diagnose 4.1.1 Target engine torque (FR) The vehicle control (FR) interprets the accelerator pedal position and derives the target engine torque (FR). The FR sends this request to the EGM via the CAN bus. The EGM accepts the target torque specification of the FR when the communication between the FR and the EGM functions properly. -
Page 56: Current Target Control Speed
Diagnose 4.1.6 Current target control speed Equivalent to the target idling speed or the target operating speed. When the M 447 hLAG is used in buses, no operating speed controllers are required. 4.1.7 Current final limit speed Final limit speeds are stored in the data record of the MR EGM. The FR can reduce the final limit speed programmed in the MR with a specification via CAN "Current final limit speed", but CANNOT increase it. -
Page 57: Exhaust-Gas Temperature
Diagnose 4.1.11 Exhaust-gas temperature The exhaust-gas temperature is calculated every 40 ms. The calculated exhaust-gas temperature is a filtered variable (low-pass filter). If the voltage of the exhaust-gas temperature sensor is above 2.7 V or below 0.3 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 6715 or 6716 is entered. -
Page 58: Coolant Temperature
Diagnose 4.1.13 Coolant temperature The coolant temperature is calculated every 40 ms. The calculated coolant temperature is a filtered variable (low-pass filter). If the voltage of the coolant temperature sensor is above 4.97 V or below 0.35 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 1515 or 1516 is entered. -
Page 59: Gas Temperature
Diagnose 4.1.14 Gas temperature The gas temperature is calculated every 40 ms. The calculated temperature is smoothed with a low-pass filter. The characteristic curve of the gas temperature sensor is stored in the engine data record. If the voltage of the gas temperature sensor is above 4.95 V or below 0.35 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below"... -
Page 60: Calculation Of Gas Pressure
Diagnose 4.1.15 Calculation of gas pressure The gas pressure is calculated every 10 ms. The calculated pressure is smoothed with a low-pass filter. The characteristic curve of the gas pressure sensor integrated in the engine control unit is stored in the control unit software. -
Page 61: Calculation Of Engine Oil Level
4.1.16 Calculation of engine oil level Oil level sensing is currently NOT offered on the M 447 hLAG gas engine and is deactivated. The oil level, top-up quantity and oil level warnings are set to "Signal not available" (s.n.a. = 102 % or -12.8 l) with the sensing function switched off. -
Page 62: Charge-Air Temperature
Diagnose 4.1.18 Charge-air temperature The charge-air temperature is calculated every 40 ms. The calculated temperature is smoothed with a low-pass filter. The characteristic curve of the charge-air temperature sensor is stored in the engine data record. If the voltage of the charge-air temperature sensor is above 4.95 V or below 0.20 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below"... -
Page 63: Boost Pressure
Diagnose 4.1.19 Boost pressure The boost pressure signal is read out and standardised in the 1 ms time slice. The calculated pressure is then filtered every 10 ms time synchronised. The characteristic curve of the boost pressure sensor is stored in the engine data record. If the voltage of the boost pressure sensor is above 4.90 V or below 0.24 V for more than 2 seconds, then the event "Measuring range exceeded or dropped below"... -
Page 64: Atmospheric Air Pressure
Diagnose 4.1.20 Atmospheric air pressure The atmospheric air pressure is calculated every 40 ms. The calculated pressure is smoothed with a low- pass filter. The characteristic curve of the atmospheric pressure sensor integrated in the engine control unit is stored in the control unit software. If the voltage of the atmospheric pressure sensor is above 4.75 V or below 2.30 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below"... -
Page 65: Oil Pressure
Diagnose 4.1.21 Oil pressure The oil pressure is calculated every 10 ms. The calculated pressure is smoothed with a low-pass filter. The characteristic curve of the oil pressure sensor integrated in the engine control unit is stored in the control unit software. If the voltage of the oil pressure sensor is above 4.92 V or below 0.25 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below"... -
Page 66: Throttle-Valve Target Position
Diagnose 4.1.22 Throttle-valve target position The throttle-valve target position is a function variable calculated by the EGM in dependence on the target torque specification and the engine speed, and is transferred to the throttle valve actuator as the target specification in the form of a PWM signal ( see Throttle valve control). -
Page 67: Lambda Correction Factor
Diagnose • The MR EGM detects the event "Measuring range implausible“ (fault code 8417) when the "Lambda- probe heating current" is less than 0.8 A or greater than 1.80 A for at least 5 seconds following the heat-up phase. In case of a fault, the Engine protection: lambda lean-controller probe becomes active. 4.1.27 Lambda correction factor The lambda correction factor is a function variable calculated by the EGM. -
Page 68: Reading Binary Values
10 = n.d. 11 = s.n.a. 00 = not active Partial load 01 = active 10 = n.d. 11 = s.n.a. the M 447 hLAG is NEVER in full-load engine state 00 = not active Full-load (ONLY idling and partial load) 01 = active 10 = n.d. - Page 69 Diagnose Information Coding Remarks (dec.) Start button on engine 00 = not actuated 01 = actuated 10 = n.d. 11 = s.n.a. 00 = not actuated Stop button on engine 01 = actuated 10 = n.d. 11 = s.n.a. 00 = not active EGM starter actuation 01 = active 10 = n.d.
- Page 70 Diagnose Information Coding Remarks (dec.) Cut-off valve state 00 = CLOSED 01 = OPEN 10 = n.d. 11 = s.n.a. n.d. = not defined s.n.a. = signal not available n.f. = still free Status September 2003 (EvoBus-Service / AFT) Page: 70 of 83...
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Page 71: Egm-Specific Customer Service Routines
Temporarily switch off LMR The M 447 hLAG is a lean engine. The lambda probe is a lean probe from Bosch with a measuring range between 0.7 and 1.9. Normally, the lambda controller works in fired operation. A very significant output variable of the lambda controller is the Lambda correction factor . -
Page 72: Switch-Off Of Gas Injectors
Diagnose 4.3.2 Switch-off of gas injectors The Customer Service routine: "Switch-off of gas injectors" enables any desired pair of gas injectors to be switched off briefly in order, for example, to investigate the suspicion of incorrectly operating gas injectors. Experience shows that the lambda correction factor changes by approx. 0.15 – when an intact pair of gas injectors is switched off. -
Page 73: Temporarily Switch Off Engine Run-On
Temporarily switch off engine run-on The M 447 hLAG is switched off with the so-called "Engine run-on" . This means that when Ter. 15 is switched off, the high and low-pressure cut-off valve are switched off (gas supply switched off), however the gas injection and ignition continue to run so that the engine continues running until the gas in the low- pressure line is consumed (to protect the catalyst) and the engine dies due to a shortage of gas. -
Page 74: Checking Egm
Checking EGM _____________________________________________________________________ 5 Checking EGM Troubleshooting The internal fault diagnosis is generally an important aid for troubleshooting so that the fault memory content should always be checked at the start of troubleshooting. 5.1.1 Engine fails to start Possible causes: 5.1.2 Engine cannot be switched off Possible causes:... -
Page 75: Reduced Engine Output
Checking EGM _____________________________________________________________________ 5.1.4 Reduced engine output Possible causes: 5.1.5 Rough engine running, traction interruption Possible causes: Status September 2003 (EvoBus-Service / AFT) Page: 75 of 83... -
Page 76: Special Tools
Spark-plug spanner (w/f 16) • Stroboscopic lamp • Socket box for 55-pin engine connector • Current probe • Oscilloscope (with at least two channels) Circuit diagram of M 447 hLAG Status September 2003 (EvoBus-Service / AFT) Page: 76 of 83... - Page 77 Checking EGM _____________________________________________________________________ Remove page in hand-out and replace with a copy of the wiring harness diagram!!! Status September 2003 (EvoBus-Service / AFT) Page: 77 of 83...
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Page 78: Engine Performance Data
Power [kW] 1000 1200 1400 1600 1800 2000 2200 Speed [rpm] Performance graph for M 447 hLAG, 185 kW M447hLAG - 185 kW at 2000 rpm / 1050 Nm at 1300 rpm 1200 1000 Torque [Nm] Power [kW] 1000 1200 1400... -
Page 79: Safety Precautions When Working On Egm
Checking EGM _____________________________________________________________________ Safety precautions when working on EGM The following safety precautions must always be observed to prevent damage to the engine components or wiring harness and to avoid endangering persons! • Never start the engine without the battery being firmly connected (battery terminals firmly connected). -
Page 80: Appendix
Appendix _____________________________________________________________________ 6 Appendix Pulse width modulated signal Many actuators around the EGM are actuated with a PWM signal. The PWM signal is characterised by the frequency f and the pulse duty factor TV. An example of such actuators are: Gas injectors Proportional valves (EPW for actuating the ATL) etc. -
Page 81: Overview Of Bus Systems (Evobus)
Appendix _____________________________________________________________________ Overview of bus systems (EvoBus) Great importance is rightly ascribed to the MR EGM, however it is only one of a large number of control units in the interconnected system of the natural-gas CITARO (the interconnected system of the natural- gas CITARO is identical to and completely compatible with the series-production model, for example as on the diesel CITARO). -
Page 82: Index
Index _____________________________________________________________________ 7 Index 1215 62 1216 62 1315 64 Air mass 67 1316 64 Atmospheric air pressure 64 1415 18, 63 1416 18, 63 1417 63 1515 58 Battery voltage 67 1516 58 Boost pressure 63 1615 65 1616 65 1617 65 1715 60 Circuit diagram 76... - Page 83 Index _____________________________________________________________________ 8115 66 Overview of bus systems (EvoBus) 81 8116 66 8374 30 8415 66 Performance data 55, 78 8416 66 185 KW 78 8417 21, 67 240 KW 55, 78 Firing angle (Cylinder 1) 67 PWM signal 80 Gas mass 67 Safety precautions 79 Special tools 76...