Mike's Workshop Manuals: Service manuals for every vehicle
Home >> GMC >> 1993 >> Forward Control 7.4 N >> Repair and Diagnosis >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Emission Systems (Gasoline) >> Air Injection System >> Notes

Air Injection System: Notes

Air Injection Reaction (AIR) system is used to reduce carbon monoxide (CO) and hydrocarbon (HC) emissions. The AIR system provides additional oxygen to continue combustion process after exhaust gases leave combustion chamber. This added air also brings catalytic converter up to operating temperature more quickly when engine is cold. The AIR system diverts air either to the exhaust manifold ports or to the air cleaner.

System consists of an air pump, an Electric Air Control (EAC) valve (2.8L engine) or an electric air control valve with relief tube (4.3L and V8 engines), solenoid, check valve(s) and plumbing. See Figure or Figure .

NOTE: On EAC valve, divert and signal tube locations are reversed from previous model year.