Range Rover P38
LAND ROVER V8
1
DESCRIPTION AND OPERATION
ENGINE MANAGEMENT SYSTEM - up to 99MY
Description
The V8 engine for models prior to 99MY is controlled
by a Sagem GEMS engine management system. The
ECM uses sensors to determine ambient conditions
and operating data and uses this data and the
information stored in an internal memory map to
control the electronic ignition and fuel injection. The
system features idle speed control, fault monitoring,
security immobilisation and engine load management
functions. GEMS can be interrogated via the
diagnostic socket to access fault codes and other
diagnostic information using Testbook.
The engine management system (EMS) maintains
optimum engine performance over the entire
operating range. The correct amount of fuel is
metered into each cylinder inlet tract and the ignition
timing is adjusted at each spark plug.
The system is controlled by the engine control module
(ECM) which receives data from sensors located on
and around the engine. From this information it
provides the correct fuel requirements and ignition
timing at all engine loads and speeds.
The fuel injection system uses a hot wire mass air
flow (MAF) sensor to calculate the quantity of air
flowing into the engine.
The ignition system does not use a distributor. It is a
direct ignition system (DIS), using four double ended
coils. The circuit to each coil is completed by
switching inside the ECM.
The on-board diagnostic system detects any faults
which may occur within the EMS. Fault diagnosis
includes failure of any EMS sensors and actuators,
emissions related items, fuel supply and exhaust
systems.
The system incorporates certain default strategies to
enable the vehicle to be driven in case of sensor
failure. This may mean that a fault is not detected by
the driver. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.
A further feature of the system is ’robust
immobilisation’, fitted to European specification
vehicles. Upon arming the alarm, the EMS ECM
disables the injectors and the Body electrical Control
Module (BeCM) inhibits the crank relay (the vehicle
cannot be started until the alarm is disarmed).
CAUTION: System sensor connectors can
be contaminated by oil or coolant when
disconnected during repair or testing. Use
a suitable cap to prevent dirt or fluid ingress.
