EGR System Ford Club Wagon E350

DESCRIPTION

Exhaust Gas Recirculation (EGR) system is used to reduce NOx emissions. This is accomplished by recycling exhaust gases back into the intake manifold, resulting in cooler combustion temperatures and controlled NOx emissions.

PORTED & INTEGRAL BACKPRESSURE SYSTEMS

Both systems are controlled by an EGR valve. When valve is open, exhaust gas enters manifold passages. When closed, no exhaust gas is allowed to enter intake manifold. Vacuum signals control opening and closing of EGR valve.

Some light duty emission systems use a backpressure transducer to aid in controlling exhaust gas recirculation. This unit senses exhaust gas backpressure and modulates vacuum signal to EGR valve in response to amount of backpressure. Backpressure is used to provide information on engine operation modes. Backpressure transducer is integral with EGR valve.

Cutaway View of EGR Valve Without Backpressure Transducer When testing, apply 8 in. Hg vacuum to EGR valve and hold it for at least 30 seconds. Scheme 61

ELECTRONIC EGR VALVE

The Electronic EGR Valve System is controlled by the Electronic Control Assembly (ECA). An (EVP) sensor mounted on top of the EGR valve sends an electrical signal of the EGR valve position to the Electronic Control Assembly (ECA). The Electronic Control Assembly (ECA) sends an electrical signal to the Electronic Vacuum Regulator (EVR) to control vacuum to the EGR valve.

Electronic EGR Valve System used with EEC equipped vehicles. Scheme 62

PRESSURE FEEDBACK ELECTRONIC

On the Pressure Feedback Electronic system an Electronic Pressure Sensor uses exhaust backpressure from the EGR valve to send a electrical signal to the Electronic Control Assembly (ECA). The Electronic Control Assembly (ECA) uses this signal to send a signal to a Electronic Vacuum Regulator (EVR). This electrical signal is converted to a vacuum signal to control the EGR valve flow.

Electronic Vacuum Regulator & Pressure Sensor Used on all EEC equipped vehicles. Scheme 63

EGR VALVE WITHOUT BACKPRESSURE TRANSDUCER

1. Check that all vacuum lines are properly routed, all connections are secure, and that vacuum hoses are not cracked, crimped or broken. When engine is cold there should be no vacuum to operate the valve. If there is vacuum, check PVS function. Replace if necessary. There should be no vacuum to valve at warm curb idle.
2. Vacuum should be available at or above part throttle with engine at operating temperature. If vacuum is not available, check PVS and replace as necessary.
3. With engine at idle, apply 8 in. Hg vacuum to EGR valve. Valve stem should move to open valve and produce a rough idle. If valve stem moves but idle does not change, remove valve and clean inlet and outlet ports with wire brush.
4. With engine at idle, trap 4 in. Hg vacuum in EGR valve and hold. Vacuum should not drop more than 1 in. Hg in 30 seconds. If vacuum drops, replace valve.

Integral Backpressure Transducer & EGR Valve Valve cannot be opened by vacuum until bleed hole is closed by exhaust backpressure. Scheme 64

EGR VALVE WITH INTEGRAL BACKPRESSURE TRANSDUCER

1. Clamp drive socket wrench into tailpipe. Socket outside diameter should be about 1/16" less than tailpipe inside diameter. Socket drive hole should be covered and socket should be inserted into tailpipe with open end facing out to ensure proper backpressure.
2. Do not block tailpipe fully or run engine faster than idle for prolonged periods of time. Be sure to remove socket from tailpipe at end of test.
3. Idle engine and apply vacuum to EGR valve gradually. EGR valve diaphragm should move smoothly and rough idle should occur. Trap 6 in. Hg vacuum in EGR valve and hold. Vacuum should drop more than 1 in. Hg in 30 seconds.
4. If vacuum does not drop or diaphragm does not move, replace valve. If diaphragm moves but idle does not change, remove valve and check for plugged inlet and outlet ports. Clean inlet and outlet ports with wire brush and install valve and retest.

Note. Electronic EGR Valve system is controlled the EEC system. This article covers testing of EGR valve only. Refer to appropriate article in the COMPUTERIZED ENGINE CONTROL section for testing of EVP sensor and Electronic Vacuum Regulator.

1. Check vacuum lines for correct routing. Disconnect vacuum hose at valve and connect vacuum gauge to hose. Disconnect connector at EVP on top of EGR valve.
2. Start engine and apply 8 in. Hg of vacuum with engine idling. Engine idle should become rough or stall. If idle did not drop, remove valve and check for plugged inlet or outlet ports. Clean ports if they are plugged. Replace valve if inlet or outlet ports are not plugged.

Note. Refer to appropriate article in COMPUTERIZED ENGINE CONTROL section for diagnosis of Pressure Feedback Electronic EGR system.

PVS with 2 Connections

1. Detach both vacuum hoses from PVS, and connect vacuum gauge to top port on PVS. Connect other PVS nipple to manifold vacuum or external vacuum supply of at least 10 in. Hg. (Scheme 65)
2. Start engine and warm until engine operating temperature is reached. If no vacuum reading is noted, PVS should be replaced. If vacuum is present, PVS is okay.

PVS with 3 Connections

1. Disconnect EGR vacuum hose from PVS and connect manifold vacuum or external vacuum source to lowest port on PVS. (Scheme 66)
2. Detach distributor supply hose from center port, and attach vacuum gauge to center port. Start engine and warm up until engine operating temperature is reached. If no vacuum is present, replace PVS. If present, PVS is okay.

Cutaway View of 2-Port PVS PVS will open when engine reaches operating temperature. Scheme 65

Scheme 66

1. Disconnect vacuum hoses at PVS valve. Connect vacuum gauge to top port of PVS. Connect external vacuum source to second port. (Scheme 66)
2. Start engine and warm up until engine operating temperature is reached. If there is no vacuum, this portion of PVS is damaged and valve should be replaced. If vacuum is present, proceed to next step. (Scheme 66): Cutaway View of 3-Port PVS Warm engine should indicate vacuum at center PVS port.
3. Connect gauge to third port and vacuum supply to bottom port. If vacuum is noted, PVS is okay. If no vacuum, replace PVS.

Cutaway View of 4-Port PVS Connect vacuum gauge to 1st and 3rd port to check PVS. Scheme 67

VENTURI VACUUM AMPLIFIER

Note. Amplifiers have built-in calibrations, and no external adjustments are required. If amplifier bias test reveals malfunction, replace amplifier. Always check venturi vacuum amplifier last, after checking all other basic EGR components.

1. With engine at normal operating temperature, curb idle set and adequate manifold vacuum supplied to system, connect vacuum gauge to hose at amplifier port "O". Gauge may read as much as 2 in. Hg at idle.
2. Disconnect venturi hose (amplifier port "V") at carburetor and increase engine speed to 2000-3000 RPM. Vacuum should not change.
3. While maintaining high engine speed, connect venturi hose. Vacuum should increase to 4 in. Hg. Return to idle. Gauge should return to initial reading. If amplifier does not perform as specified, replace amplifier.

Testing Ford Venturi Vacuum Amplifier Amplifiers do not require external adjustments. Scheme 68

VACUUM AMPLIFIER RESERVOIR

When charged with 15-20 in. Hg vacuum, vacuum loss should not exceed .5 in. Hg in 60 seconds. If it does, replace reservoir.

REMINDER LIGHT RESET PROCEDURE

1. Turn ignition off. Insert Phillips screwdriver into hole in timer unit. While pressing screwdriver in, turn ignition switch to "RUN" position.
2. Light should be on. Hold screwdriver in for 5 seconds. Remove screwdriver. Light should go out in 2-10 seconds. If not repeat steps 1) and 2).
3. Turn ignition off. Turn ignition switch to "RUN" position. Light should come on for 2-10 seconds. This checks proper reset of light module.