Engine management system - Td5 (Operation): Description and operation (page 2 of 3)

With the ECM in a 'Secure' state, it will not function unless an alarm system is fitted to the vehicle. A 'Secure' ECM cannot be configured into a 'No Code' ECM.

With the ECM in a 'No Code' state, it does not require an alarm system to be fitted to allow the engine to operate. If the ECM senses that an alarm system is fitted it will not start. A 'No Code' ECM can be configured to a 'Secure' ECM using TestBook. A 'Secure' ECM can not be configured to a 'No Code' state.

Setting up of the ECM immobilisation configurations can only be performed using TestBook.

If a vehicle stalls immediately after starting it is possible that it has been immobilised. This means either: l The ECM was configured as 'No Code' but the ECM is receiving a code at its alarm input pin. l The ECM received an incorrect code. l The ECM was expecting a security code but did not receive one at its alarm input pin.

Fuel delivery/injection control The fuel delivery/injection control delivers a precise amount of finely atomised fuel to mix with the air in the combustion chamber to create a controlled explosion.

To precisely control fuel delivery and control fuel injection, the following input conditions must be met: l CKP information. l Injection timing map information. l FT information. l ECT information.

The ECM monitors the conditions required for optimum combustion of fuel in the cylinder from the various sensors around the engine and then compares it against stored information. From this calculation the ECM can adjust the quantity and timing of the fuel being delivered to the cylinder.

The ECM uses CKP information as follows: l To calculate engine speed. l To determine engine crankshaft position.

Engine speed and crankshaft position allows the ECM to determine fuel injection timing.

The ECM also uses ECT information and FT sensor information to allow optimum fuel delivery and injection control for all engine coolant and fuel temperatures.

Turbocharger control Turbocharger control is vital to ensure the turbocharger does not over boost the engine. Within the turbocharger is a wastegate, which when operated by the turbocharger wastegate modulator will open and close a bypass valve regulating boost pressure.

The turbocharger wastegate modulator, via the ECM, controls boost pressure under the following conditions: l Acceleration. l Wide open throttle. l Idle. l Overrun.

The turbocharger wastegate modulator receives a battery voltage supply from the main relay. The ECM supplies the earth path in the form of a pulse width modulation (PWM) signal. This signal allows the turbocharger wastegate modulator to open and close the wastegate. A proportion of the exhaust gas can bypass the turbocharger through the wastegate, regulating boost pressure.