landrover Workshop Repair Guides

Land Rover Workshop Service and Repair Manuals

Operation - engine management|Page 415 > < Operation - engine management|Page 413
Page 351
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ENGINE MANAGEMENT SYSTEM - V8

18-2-52 DESCRIPTION AND OPERATION

Evaporative emission control
Due to increasing legislation, all new vehicles must be able to limit evaporative emissions (fuel vapour) from the fuel 
tank. 

The ECM controls the emission control system using the following components:

l

EVAP canister.

l

Purge valve.

l

Canister vent solenoid (CVS) valve – (NAS vehicles with vacuum type EVAP system leak detection capability 
only)

l

Fuel tank pressure sensor – (NAS vehicles with vacuum type EVAP system leak detection capability only)

l

Fuel leak detection pump – (NAS vehicles with positive pressure type EVAP system leak detection capability 
only)

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Interconnecting pipe work.

Refer to Emissions section for operating conditions of evaporative emission systems. 
 

 + 

 EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Evaporative Emission Control 

Operation.

On-Board Diagnostics (OBD) - North American Specification vehicles only
The ECM monitors performance of the engine for misfires, catalyst efficiency, exhaust leaks and evaporative control 
loss. If a fault occurs, the ECM stores the relevant fault code and warns the driver of component failure by illuminating 
the Malfunction Indicator Light in the instrument pack.

 On vehicles fitted with automatic gearbox, the ECM combines with the Electronic Automatic Transmission (EAT) ECU 
to provide the OBD strategy.

Conditions
If the OBD function of the ECM flags a fault during its operation, it falls into one of the following categories:

l

min = minimum value of the signal exceeded.

l

max = maximum value of the signal exceeded.

l

signal   = signal not present.

l

plaus = an implausible condition has been diagnosed.

Function
All of the ECM's internal diagnostic fault paths are monitored by the OBD system. Specific faults have their own 
numeric code relating to certain sensors or actuators etc. These specific faults fall into two types, error codes (E xxx) 
or cycle codes (Z xxx). E codes represent instantaneous faults and Z codes relate to codes generated after completion 
of a drive cycle.

If an emission relevant fault occurs on a drive cycle, the ECM stores a temporary fault code, if the fault does not occur 
on subsequent drive cycles the fault code stays as a temporary fault code. If the fault recurs on subsequent drive 
cycles the ECM stores the fault code as a permanent code, and depending on which component has failed the ECM 
will illuminate the MIL. 

Immobilisation system
The ECM and the body control unit (BCU) security system comprise the immobilisation system.

The ECM and the BCU combine to prevent the engine from running unless the appropriate security criteria are met. 
The ECM and the BCU are a matched pair, if either one is replaced for any reason, the system will not operate unless 
the replaced unit is correctly matched to its original specification. TestBook must be used to reconfigure the 
immobilisation system.

Conditions
The ECM operates immobilisation in three states:

l

'New'.

l

'Secure'.

l

'No Code'.

Operation - engine management|Page 415 > < Operation - engine management|Page 413