Air Injection System Ford Econoline E150

DESCRIPTION

Different systems are used on Ford Motor Co. models although the principle operation is identical. The system is used to inject fresh air into the exhaust gases to promote further oxidation of both hydrocarbons (HC) and carbon monoxide (CO), thereby reducing concentration and converting some into harmless carbon dioxide and water.

Managed air thermactor system is utilized in several electronic and non-electronic control systems to divert fresh air upstream to exhaust manifold or downstream to rear section check valve and dual bed catalyst. This system will also dump fresh air into atmosphere during some operating modes. An air control valve is used to direct air either upstream or downstream. An air by-pass valve is used to dump air into atmosphere. These valves may be separate or combined in one valve.

A dual air pump system is used on V8 heavy duty trucks. Two air pumps and 2 air by-pass valves direct air simultaneously to cylinder head check valve and to left and right exhaust manifold check valves. The system will dump air to air cleaner during decel modes and at high speed high back pressure modes.

Pulse air system or thermactor II system does not use an air pump. This system uses natural pulses, present in exhaust system, to pull air into exhaust manifold and/or catalyst through pulse air valves. Pulse air valves are connected to exhaust manifold and/or catalyst with a long tube and to air cleaner or silencer with hose.

AIR PUMP

Air pumps are belt driven and available in several different sizes, depending on application. Different pulley diameters are also available. Do not interchange any pump or pulley. Air pump supplies air to the air injection system (except on pulse air system).

AIR SILENCER

Not used on all systems, the air silencer is a combination muffler and filter for air supply pumps. Air silencer is attached to air supply pump or pulse air valve with flexible hose.

Normally Closed Valve

Valve may be mounted on air pump or in-line. A normally closed valve supplies air to exhaust system with medium and high applied vacuum signals during normal engine operating temperature, short idles and some accelerations. With low or no vacuum applied, fresh air is dumped through silencer ports of valve or through dump port. (Scheme 21)

Scheme 21

Normally Open Valve (With Vacuum Vent)

Normally open valve with vacuum vent provide a timed air dump during decelerations and also dump when a vacuum pressure difference is maintained between signal port and vent port. Signal port must have 3 in. Hg (10 kPa) more vacuum than vent port to hold the dump. This mode protects catalyst from overheating. (Scheme 22)or (Scheme 23).

Scheme 22

Scheme 23

Normally Open Valve (Without Vacuum Vent)

A normally open valve without vacuum vent provides a timed dump of air for 1.1 or 2.8 seconds (2 seconds nominal on heavy trucks) when a sudden high vacuum of about 20 in. Hg (68 kPa) is applied to signal port. This prevents backfire during deceleration.

AIR CHECK VALVE/PULSE AIR VALVE

Both valves are a one-way valve preventing backflow of the exhaust gases. Although they are similar in looks and operation, they must not be interchanged.

AIR CONTROL VALVE (SWITCH/RELIEF)

Air control valve or switch/relief valve directs air pump output to exhaust manifold or downstream to catalyst depending on engine operation. Air control valve may be used as a thermactor by-pass valve, directing air to catalyst/exhaust system or to a remote air dump location. Pressure relief valve also provides air pump protection in event of excessive exhaust back pressure or system blockage. (Scheme 24)

Scheme 24

COMBINATION AIR BY-PASS/AIR CONTROL VALVE

This valve combines the operational function of air by-pass valve and air control valve into a single unit. There are 2 normally closed type valves. One type is a non-bleed type and one is a bleed type. (Scheme 25) The bleed type have the bleed percentage molded into plastic case and are available with different percentages.

Scheme 25

DUAL THERMACTOR AIR CONTROL SOLENOID VALVE

This solenoid valve assembly consists of 2 normally closed solenoid vacuum valves which are electronically controlled. A Thermactor Air By-Pass (TAB) valve and a Thermactor Air Diverter (TAD) valve. Both valves are vented when de-energized by ECA (Electronic Control Assembly).

THERMACTOR IDLE VACUUM (TIV) VALVE

TIV valve vents vacuum signal to atmosphere when preset manifold vacuum or pressure is exceeded. It is used to divert air supply during extended idle conditions to limit exhaust temperature.

DIAGNOSIS

Note. Due to the complexity of the electronic controls, for more testing of components, see appropriate article in the COMPUTERIZED ENGINE CONTROLS section.

Disconnect outlet hose at air pump. Start engine and check for air at outlet. Pump is operating properly if air flow from outlet increases with engine speed. If defective, seized or abnormally noisy, replace pump as an assembly.

Visually check silencer for leaks or plugging. If any signs are noticed, replace air silencer assembly.

1. Ensure air pump is operating properly. Disconnect air supply hose at valve outlet. Remove vacuum line and check for vacuum signal at vacuum nipple. (Scheme 21) Remove or by-pass any restrictors or delay valves in vacuum line. Vacuum must be present before proceeding.
2. Reconnect line to valve nipple and raise engine speed to 1500 RPM. Air should be heard and felt at valve outlet. With engine at 1500 RPM, disconnect vacuum line from valve nipple. Outlet of air should be significantly decreased or shut off. Air should exit from silencer or dump port.
3. If valve does not successfully complete previous testing and air pump is operating properly, replace valve assembly.

1. Ensure air pump is operating properly. Disconnect air pump supply line at outlet. Disconnect all vacuum lines from vacuum vent and vacuum nipple. (Scheme 22)or (Scheme 23). Raise engine speed to 1500 RPM. Air supply should be heard and felt at outlet.
2. Connect a non-restricted piece of vacuum hose to valve nipple and vacuum fitting on intake manifold. Leave vacuum vent disconnected and raise engine speed to 1500 RPM. No air should be felt at valve outlet. All air should be by-passed through silencer ports.
3. Leave non-restricted piece of vacuum hose connected to nipple and plug vacuum vent with a rubber cap. Accelerate engine to 2000 RPM and suddenly release throttle. A momentary interruption of air pump supply air should be felt at valve outlet.
4. If valve does not successfully complete previous testing and air pump is operating properly, replace valve assembly.

1. Disconnect air supply line at valve outlet. Disconnect vacuum line from vacuum nipple. (Scheme 22)or (Scheme 23). Raise engine speed to 1500 RPM. Air should be felt at valve outlet.
2. Connect a non-restricted vacuum line to intake manifold vacuum fitting and valve vacuum nipple. With engine at 1500 RPM, air at outlet should be momentarily decreased or shut off. Air should be heard or felt at Air By-pass/Relief port.
3. If valve does not successfully complete previous testing and air pump is operating properly, replace valve assembly.

Check all hoses, tubes and valves for leaks due to backflow of exhaust gases. Remove valve. Blow air through valve in direction away from air pump. Air should pass through valve. Blow air through valve in direction of air pump. Air should not pass through valve. Replace valve as necessary.

AIR CONTROL VALVE (SWITCH-RELIEF)

1. Disconnect air supply hose at valve inlet. (Scheme 24) Raise engine speed to 1500 RPM and check for air supply at valve inlet. Reconnect air supply hose to valve inlet.
2. Disconnect air supply hoses from valve outlets. (Scheme 24) Remove vacuum line at vacuum nipple. Raise engine speed to 1500 RPM. Air supply should be heard and felt at valve outlet "B" with little or no air at outlet "A". (Scheme 24)
3. Connect a non-restricted vacuum line to intake manifold vacuum fitting and valve vacuum nipple. Raise engine speed to 1500 RPM. Air supply should be heard and felt at outlet "A" with little or no air at outlet "B". (Scheme 24)
4. If valve does not successfully complete previous testing and air pump is operating properly, replace valve assembly.

1. Disconnect air supply hoses from outlets "A" and "B". (Scheme 25) Disconnect and plug vacuum line to vacuum port "D". Raise engine speed to 1500 RPM. Air supply should exit out by-pass vents.
2. Reconnect vacuum line to vacuum port "D". Disconnect and plug vacuum line at port "S". With engine at idle, ensure vacuum is present in vacuum hose to port "D". Raise engine speed to 1500 RPM. Air supply should exit outlet "B" and no air should be detected at outlet "A". (Scheme 25)
3. Apply 8-10 in. Hg (27-34 kPa) vacuum to valve port "S". Raise engine speed to 1500 RPM. Air supply should exit outlet "A". If valve does not successfully complete previous testing and air pump is operating properly, replace valve assembly.

Note. If valve is of the bleed-type, function and testing is the same. However, a small amount of air will flow from outlet "A" or "B" during tests but main discharge will be switched as stated.

A functional test of each valve can be determined by externally energizing terminals. Vacuum should pass through valves when energized. Resistance of each solenoid, when checked at terminals, must be between 51-108 ohms. If not within specifications, replace solenoid valve.

Code "ASH" & "RED"

1. Connect manifold vacuum to TIV valve small nipple. With engine at idle, transmission in neutral, place fingers over the 4 TIV vent holes in base. If vacuum is NOT present, replace TIV valve.
2. Using vacuum pump, apply vacuum to TIV valve large nipple. See «TIV VALVE TEST SPECIFICATION»(/ford/econoline-e150/1987-1991/remont/testing-diagnostics/#air-injection-system) . Vacuum should no longer be present at vent holes. If vacuum IS present, replace TIV valve. Reconnect valve to original hoses.

Code "TUR"

1. Connect manifold vacuum to TIV valve small nipple. With engine at idle, transmission in neutral, place fingers over the 4 TIV vent holes in base. If vacuum IS present replace TIV valve.
2. Using vacuum pump, apply vacuum to TIV valve large nipple. See «TIV VALVE TEST SPECIFICATION»(/ford/econoline-e150/1987-1991/remont/testing-diagnostics/#air-injection-system) . Vacuum should be present at vent holes. If vacuum is NOT present, replace TIV valve. Reconnect valve to original hoses.

TIV VALVE TEST SPECIFICATIONS

See also:
• TIV VALVE TEST SPECIFICATION