Variable Induction System: Description and Operation

Secondary Air Control System:

The secondary air control system allows for reduced intake air at idle to improve idle quality and then opens above about 3500 rpm to improve engine performance and increase power.

The system consists of the secondary port valves mounted in the lower intake manifold and a vacuum operated diaphragm which moves the secondary valve linkage. An ECM controlled vacuum switching valve is utilized to control operation of the diaphragm and thus the secondary valves.

If secondary valves are open at idle, idle quality will be affected. If valves do not open, engine performance will be reduced.