Range Rover V8 Emissions: Secondary Air Injection Operation
ENGINE MANAGEMENT SYSTEM – V8
18-2-56 DESCRIPTION AND OPERATION
Secondary Air Injection
The ECM controls the secondary air injection which is used to quickly heat the catalytic converters for emission
legislation compliance.
1 Non return valve
2 Vacuum vent valve
3 Vacuum reservoir
4 SAI pump
The ECM controls the vacuum vent valve and the air injection pump relay. The air pump operates at a start
temperature of between –9
°
C and 50
°
C. The pump continues to operate for a maximum of 2 minutes, when the engine
speed drops to idle.
Note that the secondary air valve is always open when the air pump is operating.
The secondary air injection system is used to limit the emission of carbon monoxide (CO) and hydrocarbons (HC) that
are prevalent in the exhaust during cold starting of a spark ignition engine. The concentration of hydrocarbons
experienced during cold starting at low temperatures are particularly high until the engine and catalytic converter
reach normal operating temperature. The lower the cold start temperature, the greater the prevalence of
hydrocarbons emitted from the engine.
3
2
M19 3550
1
4
