Exhaust Gas Recirculation (AGR) (Opel Vectra B)

At high combustion temperatures in the engine, the proportion of nitrogen oxides in the exhaust gases inevitably increases. The possibility of reducing the temperature in the combustion chambers is ensured by introducing exhaust gases into them. From the flow of gases exhausted by the engine, a part is separated by a system regulated by a valve. Its amount is dosed depending on the engine load and returned to the intake manifold. Since the exhaust gases contain almost no particles capable of combustion, they cannot burn again. But they reduce the flow of fresh fuel-air mixture and, thus, affect the reduction of the temperature in the combustion chamber and, consequently, the reduction of the proportion of nitrogen oxides. Since recirculation of exhaust gases is necessary only at partial load, the ignition/injection control unit has a special program for recirculation of exhaust gases. The following design units are involved in this process, some of which are described in detail in the chapters devoted to injection:





Idle switch contact in throttle potentiometer; it ensures that exhaust gases are not recirculated at idle and in forced idle mode.



Coolant temperature sensor: When the engine is cold, recirculation is not needed. During the warm-up phase, a reduced amount of exhaust gases are recirculated.

Pulse sensor for signaling the speed of rotation to disable exhaust gas recirculation at speeds above 3000 rpm.

The EGR valve with pulse sensor opens the path for recirculated exhaust gases into the intake manifold, while the current valve position is signaled to the ignition/injection control unit.

The ignition/injection control unit, depending on the need, sends an activation signal to the EGR valve via two electromagnetic valves (taking into account the mentioned information at the entrance).

Advice: Malfunctions in the exhaust gas recirculation system are hardly noticeable by engine malfunctions. Preventive monitoring is not provided. In case of doubt, contact an Opel workshop with its control devices.

(Article posted on a web portal: OpelBook.ru)