Engine management system - siemens (all except NAS) (Description): Description and operation

Description

General

The KV6 engine is fitted with a Siemens Engine Management System (EMS). The Siemens EMS is an adaptive system that maintains engine performance at the optimum level throughout the life of the engine.

The EMS consists of an Engine Control Module (ECM) that uses inputs from engine sensors and from other vehicle systems to continuously monitor driver demand and the current status of the engine. From the inputs the ECM calculates the Air Fuel Ratio (AFR) and ignition timing required to match engine operation with driver demand, then outputs the necessary control signals to the fuel injectors and ignition coils. The ECM also outputs control signals to operate the: l Idle Air Control (IAC) valve. l Air Conditioning (A/C) compressor. AIR CONDITIONING, DESCRIPTION AND OPERATION, Description. l Cooling fans. l Evaporative emissions (EVAP) canister purge valve. EMISSION CONTROL - K SERIES KV6, DESCRIPTION AND OPERATION, Description. l Fuel pump. FUEL DELIVERY SYSTEM - K SERIES KV6, DESCRIPTION AND OPERATION, Description. l Variable Intake System (VIS). MANIFOLD AND EXHAUST SYSTEM - K SERIES KV6, DESCRIPTION AND OPERATION, Description.

The EMS interfaces with the: l Immobilisation ECU, for re-mobilisation of the engine fuel supply. SECURITY, DESCRIPTION AND OPERATION, Description. l Cruise control interface ECU, to enable the system. ENGINE MANAGEMENT SYSTEM - SIEMENS (ALL EXCEPT NAS), DESCRIPTION AND OPERATION, Description. l Electronic Automatic Transmission (EAT) ECU, to assist with control of the gearbox. AUTOMATIC GEARBOX - JATCO, DESCRIPTION AND OPERATION, Description.

Sensor inputs and engine performance are monitored by the ECM, which illuminates a Malfunction Indicator Lamp (MIL) if a fault is detected.

As part of the security system's immobilisation function, a vehicle specific security code is programmed into the ECM and immobilisation ECU during production. The ECM cannot function unless it is connected to an immobilisation ECU with the same code. In service, replacement ECM are supplied uncoded and must be programmed using TestBook to learn the vehicle security code from the immobilisation ECU.

A 'flash' Electronic Erasable Programmable Read Only Memory (EEPROM) allows the ECM to be externally configured, using TestBook, with market specific or new information.

The ECM memorises the position of the crankshaft and the camshaft when the engine stops, which allows immediate sequential fuel injection and ignition timing during cranking on the subsequent start. The position data is lost if the battery is disconnected or the battery voltage is too low. After battery reconnection or recharging, during the subsequent start sequence fuelling and ignition is delayed slightly until the ECM has determined the position of the crankshaft and the camshaft from the CKP and CMP sensor inputs.

To achieve optimum performance the ECM is able to 'learn' the individual characteristics of an engine and adjust the fuelling calculations to suit. This capability is known as adaptive fuelling. Adaptive fuelling also allows the ECM to compensate for wear in engine components and to compensate for the tolerance variations of the engine sensors.

If the ECM suffers an internal failure, such as a breakdown of the processor or driver circuits, there is no back up system or limp home capability. If a sensor circuit fails to supply an input, where possible the ECM adopts a substitute or default value, which enables the engine to function, but with reduced performance.