Electronically Controlled System

1985-87 MODELS W/HEAVY DUTY EMISSIONS

DESCRIPTION
The air injection system used on vehicles with heavy duty emissions utilize increased air flow over other models to reduce CO and HC emission levels. The AIR system provides additional oxygen to continue combustion after the exhaust gases leave the combustion chamber. This system diverts air from the exhaust manifold at increased engine speed or when a malfunction is detected in the system.
The AIR system used on vehicles equipped with a 6-292 engine consists of an air pump, air filter, air control valve, check valve,silencer, control module and injection nozzles.
The AIR system used on vehicles equipped with V8-350 or V8-454 engines consists of two air pumps, air filter, two air control valves,a control module and injection nozzles.

Electric Air Control (EAC) Valve:

SYSTEM COMPONENTS

Air Control Valve
This valve is a high flow electric air control valve that is equipped with an electric solenoid to combine electronic control with normal diverter valve function, Fig. 11.
With ignition ``On'', the solenoid is energized through the control module and the air control valve operates like a diverter valve directing air to the exhaust manifold. During engine deceleration, when there is a rise in manifold vacuum, air is directed to the air cleaner or silencer even though the solenoid is energized. The solenoid is de-energized when there is a malfunction of the electrical circuit or high engine RPM over a prolonged period.

Deceleration Valve (DEC-V) Operation:

Deceleration Valve
The deceleration valve is used with the AIR system to help prevent backfiring during high vacuum conditions, Fig. 17. Vacuum draws the mixture valve diaphragm down and opens the valve allowing air from the air cleaner to flow into the intake manifold.

Air Pumps(s)
Refer to ``Air Pump, Except Electronically Controlled System''.

DIAGNOSIS & TESTING
Refer to ``Except Electronically Controlled System Diagnosis & Testing'' for service procedures not covered in this section.

Fig. 18 Control module test. 1985-87 models w/ heavy duty emissions:

Control Module Test

1. Turn ignition to ``On'' position.
2. Disconnect each solenoid connector, then using a suitable test light, check for voltage between solenoid connector pink/black wire and ground , Fig. 18.
3. If voltage does not exist, check for an open in circuit 39. If voltage does exist proceed to step 4.
4. Check solenoid terminals for voltage. If voltage exists, check solenoid resistance. If resistance is less than 20 ohms, replace solenoid and valve. If voltage does not exists, check for open in circuit 436 or for a faulty control module.
5. Connect solenoid connectors, then disconnect connector at control module. Check for voltage between terminals ``A'' and ``B'', Fig. 18. If voltage exists, replace module. If voltage does not exists, check for an open circuit to the control module.

SYSTEM SERVICE
Refer to ``Except Electronically Controlled System System Service'' for service procedures not covered in this section.

Filter, Replace

1. Loosen clamp securing filter, then remove filter from clamp.
2. Disconnect hose from air intake and pump.
3. Reverse procedure to install.

Silencer, Replace

1. Disconnect hose from silencer.
2. Remove bolt securing silencer, then silencer.
3. Reverse procedure to install.

CABALLERO & EL CAMINO

DESCRIPTION
Air Management Injection Reaction systems are used to provide filtered fresh air, under pressure, to the engine exhaust stream. The exhaust gasses react with oxygen in the air, continuing the combustion process after gasses leave the combustion chamber. Continued combustion helps reduce HC and CO levels in the exhaust and aids in maintaining ideal catalytic converter operating temperatures. Regulation of the injected air on Air Management Systems is controlled by the Electronic Control Module (ECM).

Fig. 19 Typical Air Management System.:

SYSTEM COMPONENTS
This system consists of a belt driven pump, Fig.19, internal passages in the cylinder heads or manifolds, piping and hoses, ECM controlled valves and check valves. The dual bed catalytic converter, if equipped, is also considered part of this system. The air pump operates whenever engine is running, drawing air in through an integral filter, and delivering the air to ECM controlled valves for distribution. Excess air is discharged through a pressure relief valve, located either on the pump or in the ECM controlled valve assembly.
When engine is cold, air is routed to the exhaust port area of the cylinder head or manifold, Fig. 19. Unburned exhaust gasses combine with oxygen in the air, reducing HC and CO levels and speeding warm-up of the catalyst and oxygen sensor. During normal operation, air is either routed to the dual bed catalyst to provide additional oxygen for the oxidizing catalyst, or diverted to the air cleaner or atmosphere. During deceleration or wide open throttle on most models, air is diverted from the system to the air cleaner or atmosphere. Check valves prevent exhaust gasses from flowing back through the air distribution system.

Fig. 20 Electric Air Control/Electric Air Switching (EAC/EAS) valve. Integral type:

Fig. 21 Electric air control valve operation:

Fig. 22 Electric air switching valve operation:

Electric Air Control & Electric Air Switching (EAC/ES)
Models with this system have 2 valves which provide air control and air switching. The system can be identified by the separate mounting of the 2 valves or by the vacuum divert hose position on the integral type EAC/ES valve, Fig. 20. The first valve (EAC) directs air pump output into the system, or diverts it to the air cleaner. The second valve (ES) directs EAC valve output to either the exhaust ports or catalytic converter. Vacuum signals, controlled by an Electronic Control Module (ECM), operate on both valves.
During normal operation, the EAC valve solenoid is energized by the ECM, Fig. 21. Air pump output is directed to the air switching valve unless there is a sudden rise in intake manifold vacuum, such as during deceleration. A sudden vacuum rise closes the valve, diverting air pump output to the air cleaner until the vacuum has equalized in the decel timing assembly.
Under certain operating conditions, the ECM de-energizes the EAC solenoid to provide electric divert. When the solenoid is de-energized pressurized air enters the decel timing chamber and closes the valve, causing air pump output to divert to the air cleaner. Excess air pump output is also exhausted to the air cleaner through relief valve in the EAC assembly, Fig. 20. The Electric Air Switching (ES) valve directs EAC valve output depending upon engine operating mode. When engine is in ``Open Loop'' mode the ECM energized the ES valve solenoid, Fig. 22, and vacuum opens the air passage to the exhaust ports. When engine is in ``Closed Loop'' mode the solenoid is de-energized, the vacuum signal is blocked, and spring tension opens the air passage to the catalytic converter.

Fig. 23 Electric Divert/Electric Air Switching (ED/ES) valve:

Fig. 24 ED/ES valve normal operation. ``Open Loop'' mode:

Fig. 25 ED/ES valve electric divert:

Electric Diverter/Electric Air Switching (ED/ES)
Electric divert air control and electric air switching are combined into one valve assembly, which can be identified by the vacuum signal hose position, Fig. 23. The valve is operated by vacuum signals which are solenoid-controlled through an Electronic Control Module (ECM).
During normal operation the ECM energizes the air control (lower) solenoid, Fig. 24. Manifold vacuum holds the valve open and air is directed to the air switching valve. If engine is operating in ``Open Loop'' mode, the ECM energizes the air switching (upper) solenoid, Fig. 24, and manifold vacuum opens the air passage to the exhaust ports. If engine is operating in ``Closed Loop'' mode, the air switching solenoid is de-energized, and spring tension opens the air passage to the catalytic converter.
When the ECM determines that air should be diverted from the system, the solenoids are de-energized, spring tension closes the valves, and air pump output is diverted to the air cleaner, Fig. 25. Under low manifold vacuum conditions, as in wide open throttle operation, vacuum in the air control chamber drops, spring tension closes the air control valve, and air is diverted to the air cleaner, Fig. 26. Excess air pump output is also exhausted through a pressure relief valve.

Pressure Operated Electric Diverter/Electric Switching (PEDES)
This system is ECM operated similarly to the ED/ES type, but uses air pump pressure rather than intake manifold vacuum to operate control valves. Air pump pressure builds up against a control valve which is operated by the ECM through 2 solenoids.
When engine is cold (``Open Loop''), the port solenoid is energized and air pump pressure opens the passage to the exhaust ports. During normal operation (``Closed Loop''), the port solenoid is de-energize, the converter solenoid is energized, and air pump pressure opens the passage to the catalytic converter. When the ECM determines that air divert is necessary, both solenoids are de-energized and air pump output is diverted to the air cleaner through a divert/relief valve. The divert/relief valve limits system pressure.

Electric Diverter (ED)
This system is used on models that do not require air injection into the catalytic converter, and is controlled by an Electronic Control Module (ECM). When engine is operating in ``Open Loop'' mode, the valve is energized and air pump output is directed to the exhaust ports. However, a sudden rise in manifold vacuum will close the valve, momentarily diverting air to the air cleaner. When engine is operating in ``Closed Loop'' mode, the valve is not energized and the vacuum signal is blocked. Air pump pressure closes the valve and air is diverted to the air cleaner.

Fig. 27 Computer operated vacuum switching valve:

Vacuum Switching Valve
The VSV is used on models with Closed Loop Fuel Control (CLFC) to control operation of an AIR Switching Valve (ASV). The VSV applies either pressure or vacuum signals to the ASV control diaphragm, depending upon voltage signals from the CLFC computer, and the ASV controls air flow in the AIR system.
The VSV, Fig. 27, receives pressurized air from the air pump through a tap in the ASV and operating vacuum from the intake manifold. When the VSV is energized by the computer, operating vacuum is directed to the ASV control diaphragm. When the VSV is de-energized, air pump pressure is directed to the ASV control diaphragm.
The ASV directs air pump output into the injection manifold or diverts the air to atmosphere. In addition, an internal bleed allows a small portion of the air pump output to be directed to the VSV to act as a control signal. When vacuum is applied to the ASV control valve diaphragm, the control valve opens the passage to the injection manifold and air is injected into the exhaust stream. When pressure is applied to the control valve diaphragm, the control valve closes the port to the injection manifold and opens the air divert port, diverting air pump output to the air cleaner.

Deceleration Valves
Some engines are equipped with Deceleration Valves (DEC-V), or Mixture Control Valves (DEC-MCV), in order to prevent back firing on deceleration due to rich air/fuel mixtures. For description and operating characteristics of these valves, refer to ``Except Electronically Controlled System'' section.

SERVICE
Air Management System control valves and solenoids are not serviceable. If a component is found defective during testing, it must be replaced. Refer to ``Except Electronically Controlled System'' section for air pump, check valve and injection manifold replacement procedures.
System operation should be checked and components inspected every 24 months or 30,000 miles. The air pump drive belt should be inspected every 6 months or 6,000 miles, and adjusted or replaced as needed.