Closed - loop emission control

Closed - loop emission control

The M.E.M.S. S.P.i. system operates a closed loop emission system to ensure the most efficient level of exhaust gas conversion.

An oxygen sensor (36) fitted in the exhaust down pipe monitors the exhaust gases. It then supplies a small voltage proportional to exhaust oxygen content to the engine management E.C.U. (1). As the air/fuel mixture weakens, the exhaust oxygen content increases and so the voltage to the E.C.U. increases. If the mixture becomes richer so the oxygen content decreases and with it the voltage.

The E.C.U. uses this signal voltage to determine the air/fuel mixture being delivered to the engine, and adjusts the injector duration to maintain the ratio necessary for efficient gas conversion by the catalyst.

The oxygen sensor has an integral heating element to ensure an efficient operating temperature is quickly reached from cold. The electrical supply for the heater element is controlled by the oxygen sensor relay(39).

Non - evaporative loss equipment

Charcoal canister

A charcoal canister (37) is used for the temporary storage of fuel vapour from the fuel tank until the vapour can be purged from the canister into the engine and burned.

The charcoal canister is purged when the purge control valve is open, fresh air is drawn through the purge air hose, through the charcoal canister and into a port in the throttle housing.

Vapour purge control valve

A purge control valve (38) is operated by the Engine Management E.C.U. The valve remains closed when the engine is cold and at idling speed to protect engine tune and catalyst performance. When the engine is above 70°C, the purge valve solenoid will be modulated ON and OFF whenever the engine speed is above 1500 rev/min and the manifold absolute pressure is below 30 kpa. When the purge valve is opened, fuel vapour from the charcoal canister is drawn into the throttle housing for combustion.