LR3/Disco 3
The ECM alters the PWM signal to the purge valve to control the rate of purging of the canister. The purging of the
canister is done in a controlled manner in order to maintain the correct stichometric air/fuel mixture for the engine. It also
ensures the canister itself is purged frequently enough to prevent fuel saturation of the charcoal leading to an excessive
build up of fuel vapour (and hence vapour pressure) in the system which could increase the likelihood of vapour leaks.
For additional information, refer to
Evaporative Emissions
(303-13A Evaporative Emissions - 4.0L)
