General information
The electronic engine management system regulates the amount of fuel supplied to the cylinders and controls the ignition process. Gasoline engines use various control systems (see The operating principle of fuel injection systems).
The electronic engine management system provides the following capabilities:
- Precise fuel dosing in any operating mode, which ensures low fuel consumption with high power.
- Reduction of the content of harmful substances in exhaust gases thanks to precise fuel dosing and the use of a catalytic converter.
- Self-diagnosis of the engine management system provides the ability to quickly find a fault. One of the most important elements of the engine management system is the self-diagnosis subsystem. If during operation a failure of any of the system elements is detected, the corresponding fault code is entered into the ECM processor memory. Reading and identification of codes stored in memory (see Chapter Engine electrical equipment) allows you to quickly identify and eliminate the cause of the failure.
The engine control unit (ECM) acts as the brain center and is equipped with a high-speed microprocessor. Based on the analysis of data continuously received from information sensors, the ECM determines the optimal injection moment and the required volume of fuel to be injected. Information processed by the transmission control modules and the engine immobilizer is also taken into account.
The engine management system elements maintain high performance for a long time and require virtually no maintenance. Only such system elements as the air filter and spark plugs require regular replacement during vehicle maintenance. Serious adjustment and repair work requires the use of complex diagnostic devices, which is why their implementation should be entrusted to service station specialists.
Adjustment of idle speed and carbon monoxide (CO) concentration is not required as part of maintenance.
Safety precautions when working with the gasoline engine control system
Remember that the fuel inside the fuel system tract is under pressure when the engine is running and the ignition is on. Residual excess pressure continues to be retained in the system for some time after the ignition is turned off and must be released before disconnecting components/disconnecting nipple connectors!
Do not touch or disconnect the ignition system high voltage wiring while the engine/starter is running.
Persons with an implanted pacemaker must under no circumstances be allowed to service ignition system components! Connecting and disconnecting measuring instruments must also be done with the ignition switched off.
Disconnection of fuel lines must be carried out with the ignition off.
When checking the compression pressure in the cylinders, the fuel and ignition systems must be disconnected (see the corresponding Section of the Chapter Engine)
See also the list of safety measures - see. Power supply system.
Notes on Engine Management System Tests
When searching for the causes of failures, first of all, it is necessary to remove diagnostic codes from the processor memory, and also check the tightness of the vacuum line connections.
For reliable operation of all electrical elements of the system, a voltage of at least 11.5 V is required.
If after completing the search and elimination of the causes of failures the engine immediately stalls after starting, the cause of this phenomenon may be the blocking of the anti-theft system - query the processor memory, if necessary, adjust the corresponding control unit.
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