Air Injection

RESONANCE FLAP CONTROL CIRCUIT DIAGRAM:

B. AIR INJECTION

The DME Control Unit (7) will ground pin 23 for a maximum duration of 125 sec. based on three parameters and when the following conditions are met:

- start signal (the engine is being started);

- engine speed (below 4,600 RPM);

- engine temperature (taken from the coolant temperature sensor, front right side of engine, temp. below 86~F/30~C).

If one of the above conditions is not met, pin 23 will not be grounded. What happens if pin 23 is grounded? Relay (8) will energize (in parallel circuit) both the magnetic clutch of the belt-driven air pump (9) and the changeover valve (10). The air pump will send pressurized air via the vacuum controlled valve (11) and the check valve (12) to be injected into the exhaust manifold.

Changeover valve (10), when energized, will send vacuum to vacuum controlled valve (11). Vacuum is used as a medium to open valve (11), that is, to direct pressurized air from the air pump to the exhaust.

The purpose of vacuum controlled valve (11) is twofold:

- it will open the pressure line between pump and exhaust manifold. If changeover valve (10) is not energized, the hose between air pump (9) and vacuum controlled valve
(11) will be open to the atmosphere. This is the case under most operating conditions of the vehicle.

- it will prevent air from being sucked into the exhaust during normal operating conditions. This might happen because of exhaust gas resonances.

Check valve (12) prevents exhaust gas from reaching vacuum controlled valve (11).

Pressure control valve (13) is a spring-loaded check valve that will prevent an overpressure in the line; it will release excessive air pressure to the atmosphere.
Component Location:

(7) DME Control Unit: E-Box.

(8) Relay: E-Box as one of the three relays; it replaces the oxygen sensor relay, (9) Air pump: V-belt driven, front side of engine.

(10) Changeover valve: adjacent to the idle control valve underneath the # 1 and # 2 intake runners.

(11) Vacuum controlled valve: right front side of engine block.

(12) Check valve: right front side of engine block.

(13) Pressure control valve: right front side of engine block; bolted to block.