Vehicle Engine Management Systems

Unit 52:

Level:  3

Guided learning: 60 hrs

 

Unit introduction

Modern motor vehicles continue to make use of the rapid advances in electronics technology in a wide range of vehicle applications. This unit considers how electronics are used in engine management systems (EMS) and, in particular, the use of engine control units (ECU) that control different aspects of an engine’s operation.

As a minimum, a simple ECU may just control the quantity of fuel injected into each cylinder during each engine cycle. However, advanced ECUs also control the ignition timing, variable valve timing, the level of boost maintained by a turbocharger and may also control a range of other engine system peripherals. Increasingly, the EMS also plays an important part in maintaining environmental controls, fuel economy and safety and in ensuring compliance with the various legislative requirements placed on modern engines.

This unit will enable learners to gain an understanding of the systems and operating principles of an EMS. Learners will consider the interaction between the EMS and the functions and performance of a modern motor vehicle engine. They will also carry out a series of EMS tests and will select and use equipment to carry out a diagnostic test to determine EMS faults.

Note that the use of ‘e.g.’ in the content is to give an indication and illustration of the breadth and depth of the area or topic. As such, not all content that follows an ‘e.g.’ needs to be taught or assessed.

 

Learning outcomes

On completion of this unit a learner should:

  • Understand the operating principles and characteristics of an engine management system
  • Understand the operating principles of engine management system sensors and actuators
  • Understand the interrelationships and interaction of engine management systems and components
  • Be able to carry out tests on an engine management system to locate a system

 

Unit content

 

  • Understand the operating principles and characteristics of an engine management system

Operating principles and characteristics: systems modelling, e.g. diagrammatic representation of system input/process/output, characteristics of open- and closed-loop system control strategies used in engine management systems; control systems, e.g. analogue, digital, programmable, non-programmable; main elements of a digital processing system, e.g. central processing unit (CPU), memory devices (such as volatile, non-volatile), buses, input/output ports; principal functions of a digital processing system, e.g. multiplexing, controller area network (CAN) systems; characteristics, e.g. purpose and applications of the system, operating conditions (conditions in which the system is operative or inoperative, ‘fail-safe’ features), system features (benefits, cost, performance, safety, convenience, efficiency)

Engine management systems: integration developments, e.g. fuel, mechanical to full electronic; interaction between other vehicle systems, e.g. sport mode on gearbox selection; fuel management (spark and combustion ignition) systems; ignition control and combined fuel/ignition control; emission control, e.g. active to reactive such as use of lambda system and knock sensor control; vehicle performance monitoring, e.g. throttle position, driver selection

 

  • Understand the operating principles of engine management system sensors and actuators

Operating principles of sensors: types, e.g. electromagnetic, Hall effect, photo-electric, resistive, inductive, piezo-electric element effect, capacitive; factors affecting performance and application, e.g. sensitivity, accuracy, linearity and stability; influence of environmental, factors e.g. heat, vibration, moisture, contaminants

Operating principles of actuators: e.g. ignition components such as coils, high tension (HT) components (individual coils, spark generators), fuel components (idle control valves, cold start devices, electronic injectors), variable valve timing control

 

  • Understand the interrelationships and interaction of engine management systems and components

Interfacing and signal processing: compatibility between components and systems, e.g. temperature and speed sensors, throttle position/drive by wire actuators; characteristics of devices which give rise to the need for signal processing (inductive pick-ups, analogue to digital (A/D) and digital to analogue (D/A) conversion); control of output devices e.g. energy transfer, power output stages, buffer circuits

Functional interrelationships: location, e.g. units and components in the vehicle, position/location of components relative to others in the system; functional relationships between the elements of the system, e.g. data input from sensors and electronic control unit (ECU) process to affect actuation; impact of a component’s failure on other components in the system, the operation of the system and on external systems, e.g. the effect of speed sensor failure, Lambda sensor fault

System interactions: e.g. integration fuel and emission control and/or vehicle performance control, achieved by common data sources and actuator responses

 

  • Be able to carry out tests on an engine management system to locate a system fault

Test components/circuits for satisfactory operation: test equipment,

e.g. onboard diagnostics, test instruments, voltage drop tester, ECU tester, spark advance and retard tester; safe working practice, e.g. common rail fuel pressures, working with ECU, HT voltage; components and circuits, e.g. fuses, wiring, connectors, injector, coil, ECU, pulse generator, sensors/transducers (such as crankshaft, camshaft, knock), actuators, pressure check (fuel pump), break out box; checking for faults, e.g. moisture, dirt, corrosion, fault code reading, gap, data link connection, output and resistance, condition, ignition timing, sensor output, sensor operation

Course Details