Omega B
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Function
The new X 20 XEV engine is equipped with the modern engine management system Simtec 56.1. The functioning of the Simtec 56.1 essentially corresponds to that of the Simtec 56 of the C 18 XE engine on the Astra - F, which has already been described in the "Product Description, Model Year 1993 1 / 2" brochure.
In contrast to the C 18 XE engine, the X 20 XEV is also fitted with an EGR system and secondary air injection to conform to the exhaust emission limits set down in the new European exhaust legislation.
The familiar fuel pump relay which supplied the fuel pump and the injectors with voltage is no longer used. Its function is taken over by two relays, the fuel pump relay and the reverse battery protection relay. These relays are similar in appearance but have different constructions, and are therefore not interchangeable. They are located in the engine compartment relay frame.
The oxygen sensor operates on resistance (TiO2), not voltage (Zr O2).
The EGR system returns a specific amount of exhaust gas to the combustion process via a regulated EGR valve. This reduces the formation of nitrogen oxides (NOx).
In the secondary air injection system, an electrically driven secondary air pump is switched on via a relay in the partial load range. It injects air into the oxidation catalytic converter, reducing the amount of CO and HC emissions.
When the ignition is switched off, data (such as calculated values / learned values, MT or AT transmission, trouble codes, version codes) is now stored in an EEPROM and not in a battery - buffered RAM,
Advantages:
Guaranteed storage of data, even when battery voltage is disconnected. Previous MT / AT and version coding plugs are not required.
Codes can be deleted (on replacement of the control unit) by reinitialising the EEPROM with TECH 1.
The following parameters can be modified when performing version coding with TECH 1:
- Idle speed can be increased in three steps of 50 rpm each.
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