DESCRIPTION
The pulse air injection system is used to inject fresh air into the exhaust system. When fresh air is injected into the hot exhaust gasses, combustion takes place. This reduces the amount of unburned fuel that escapes to the atmosphere.
The system consists of check valves, control valves, control valve solenoids, a vacuum reservoir, vacuum lines and air lines. The pulse air system is capable of injecting air at both the catalytic converter (downstream) or the front exhaust pipe.
OPERATION
The pulse air system uses the alternating positive and negative pressure pulsations in the exhaust system to draw in fresh air through the air cleaner. Check valves are used to allow fresh air into the exhaust, but prevent exhaust from flowing back into the intake system.
Air is switched between upstream and downstream injection by 2 vacuum operated control valves. Each control valve is switched by an electrically operated vacuum solenoid.
The vacuum solenoids are switched on and off by the MCU according to engine operating conditions. A vacuum storage tank maintains the vacuum supply to the switching solenoids.
DIAGNOSIS & TESTING
- Check condition of all hoses and lines in system. Reroute any kinked or restricted hoses. Repair or replace any cracked or broken hoses. To check system operation, feel for suction in injection hoses at air cleaner.
- If a problem exists, check to see if vacuum is being supplied to the valve. If vacuum is not present at the valve(s) perform appropriate test(s). See appropriate article in Computerized Engine Control section.
