Engine Controls - System/component Tests - 1.9l Ford Escort V

INTRODUCTION

Prior to testing separate components or systems, it is recommended that all procedures listed in the BASIC TESTING article be performed. Since many computer controlled and monitored components will set a service code if they malfunction, check EEC-IV system and retrieve service codes. See Quick Test procedure in the appropriate TESTS W/CODES article in this section. If service codes are present see appropriate CIRCUIT TEST in the appropriate TESTS W/CODES article in this section.

Note. Testing individual components does not isolate shorts or opens. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) that has a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

Note. For wiring diagrams not shown in testing procedures, see WIRING DIAGRAMS .

Ground Circuits

1. Using a DVOM, check for continuity to ground on ECA terminals No. 40 and 60. Resistance should be zero ohms. If not, repair open to ground.
2. Using a voltmeter, touch negative lead of voltmeter to a good ground. Touch positive lead of voltmeter to each ground terminal. With vehicle running, the voltmeter should indicate less than one volt. If voltmeter reading is greater than one volt, check for open, corrosion or loose connection on ground lead.

Power Circuits

Using a voltmeter, check for battery voltage between ECA terminal No. 1 (KAPWR) and ground. Check for battery voltage at terminals No. 37 and 57 (VPWR). If battery voltage is not present, power is not being supplied from EEC power relay. See CIRCUIT TEST B in the appropriate TESTS W/CODES article.

ENGINE SENSORS & SWITCHES (ECA INPUTS)

Note. For additional sensor testing specifications, see SENSOR RANGE CHARTS article in this section.

AIR CHARGE TEMPERATURE (ACT) SENSOR

Sensor is located in throttle body or air cleaner. Sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, sensor may be checked by measuring resistance between sensor terminals. For specifications, see the SENSOR RANGE CHARTS article. For additional testing information and circuit testing of sensor, see CIRCUIT TEST DA in the TESTS W/CODES article.

BAROMETRIC PRESSURE SENSOR (BP)

Faults in barometric pressure sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DF in the appropriate TESTS W/CODES article for sensor specifications.

CYLINDER IDENTIFICATION SENSOR (CID) & CRANKSHAFT SENSORS

CID sensor is mounted at camshaft. Disconnect sensor connector and measure resistance across sensor terminals. Resistance should be 300-750 ohms. For additional information and circuit testing information on this sensor, see CIRCUIT TEST DR in the appropriate TESTS W/CODES article.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

Sensor is located in intake manifold cooling passage at front of most engines. Sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, sensor may be checked by measuring resistance between sensor terminals. For specifications, see SENSOR RANGE CHARTS article. For additional testing information and circuit testing of sensor, see CIRCUIT TEST DA in the appropriate TESTS W/CODES article.

EGR VALVE POSITION (EVP) SENSOR/EGR VACUUM REGULATOR (EVR) SOLENOID

Faults in sensor or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DN also in the appropriate TESTS W/CODES article for sensor specifications and circuit testing procedure.

EGR PRESSURE FEEDBACK (PFE) SENSOR/DELTA PFE/EGR VACUUM REGULATOR (EVR) SOLENOID

These sensors are used to monitor EGR system operation. Sensors are located in the EGR system or are connected to EGR system by a vacuum/pressure tube. Faults in sensor or circuit should set a service code. See Quick Test procedure in TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DL in the appropriate TESTS W/CODES article for sensor specifications and circuit testing procedure.

HEATED GAS OXYGEN (HEGO) SENSOR

Vehicle may be equipped with one or two HEGO sensors. They are located in the exhaust pipe upstream of the catalytic converters. Faults in sensor or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST H in the appropriate TESTS W/CODES article for additional sensor specifications and circuit testing procedures. Ensure that none of the following conditions exist

1. Moisture inside sensor/harness connector.
2. HEGO sensor coated with contaminants.
3. Sensor circuit open or shorted to ground.

INERTIA SWITCH

Ensure key is off. Locate inertia switch in rear of vehicle. Push down on reset button to ensure switch is closed. Measure resistance between terminals on 2-wire switches. On 3-wire switch used on 1.9L Escort, measure resistance between GND and FP terminals. (Scheme 115) If resistance is 5 ohms or less, switch is okay. For additional circuit testing information refer to CIRCUIT TEST J in the appropriate TESTS W/CODES article. If resistance is greater than 5 ohms, replace switch.

Note. In closed position, reset button can be depressed an additional 1/16" against spring. This is normal and does not affect switch operation.

Scheme 115

KNOCK SENSOR (KS)

The KS is located on cylinder block. Faults in sensor or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DG in the appropriate TESTS W/CODES article for additional sensor specifications and circuit testing procedures. Sensor is tested by substitution or by manually generating a knock to ensure sensor will set a service code.

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR

Sensor is located on engine or firewall and is connected to intake manifold by a vacuum supply hose. Remove vacuum supply hose to sensor. Install vacuum pump to sensor and apply 18 in. Hg vacuum. Sensor should hold vacuum. If sensor does not hold vacuum, replace sensor. Faults in MAP sensor or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DF in the appropriate TESTS W/CODES article for additional sensor testing and specifications.

MASS AIRFLOW (MA) SENSOR

Faults in MA sensor or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DC in the appropriate TESTS W/CODES article for sensor and circuit testing and specifications.

NEUTRAL DRIVE SWITCH (NDS) A/C INPUT

With ignition switch in off position, set DVOM to 200-ohm scale. Locate NDS switch (on transmission) and clutch switch (on clutch pedal linkage). Disconnect harness at both switches. Measure resistance across NDS terminals with transmission in NEUTRAL and across clutch switch terminals with clutch pedal fully depressed. If each resistance is greater than 5 ohms, switches are open. Replace switches. Faults in switches or switch circuits should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST TA in the appropriate TESTS W/CODES article for additional switch testing and specifications.

POWER STEERING PRESSURE SWITCH (PSPS)

1. Disconnect PSPS connector at steering gearbox. Set DVOM to 200-ohm scale and connect test leads to switch. Turn ignition switch to ON position. With steering wheel centered, resistance should be 10 ohms or less. Start engine and turn steering wheel one-half turn and then return it to centered position.
2. Resistance should change from less than 10 ohms to infinity and return to less than 10 ohms when steering wheel is returned to centered position. Faulty PSPS or circuit should set a service code. See Quick Test procedure in the TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST FF in the appropriate TESTS W/CODES article for additional switch testing and specifications.

THROTTLE POSITION SENSOR (TP OR TPS)

Faults in TP sensor or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DH in the appropriate TESTS W/CODES article for additional sensor testing and specifications. Ensure none of the following conditions exist

1. Binding throttle linkage.
2. TP sensor loose or not seated properly.
3. Throttle plate not fully closed.

VEHICLE SPEED SENSOR (VSS)

Disconnect VSS electrical connector. Using DVOM measure resistance across sensor terminals. Resistance should be 190-250 ohms. Replace sensor if not within specification. Faults in VSS sensor or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DP in the appropriate TESTS W/CODES article for additional sensor testing and specifications.

FUEL PUMP RELAY

Remove relay from vehicle. Connect battery voltage to terminal "C". Ground terminal "D". (Scheme 116) Measure resistance between terminals "A" and "B". Resistance should be less than one ohm with power applied and greater than 10 k/ohms with power removed.

Scheme 116

CANISTER PURGE SOLENOID (CANP)

1. Disconnect CANP solenoid harness connector. Set DVOM to 200-ohm scale. Measure resistance across CANP solenoid terminals. Resistance should be 40-90 ohms. If resistance is not as specified, replace CANP solenoid.
2. Disconnect vacuum hose at CANP solenoid on manifold vacuum side. Apply 16 in. Hg vacuum to manifold vacuum side of solenoid. CANP solenoid should hold vacuum for 20 seconds.
3. Faults in CANP solenoid or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST KD in the appropriate TESTS W/CODES article for additional solenoid and circuit testing.

EXHAUST GAS RECIRCULATION (EGR) SOLENOID

See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS .

IDLE SPEED CONTROL (ISC) SOLENOID

1. Solenoid is by-pass air type solenoid. Ensure ignition is off. Disconnect ISC solenoid harness connector. Set DVOM to 200-ohm scale. Measure resistance between ISC solenoid terminals. (Scheme 117) There is a diode in solenoid, connect DVOM (+) test lead to VPWR terminal and DVOM (-) lead to ISC terminal.
2. Resistance should be 7-13 ohms. If resistance is not within specification, replace solenoid. Faults in ISC solenoid or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article in this section. If no service code has been set, see CIRCUIT TEST KE in the appropriate TESTS W/CODES article for additional solenoid testing and specifications.

Scheme 117

FUEL SYSTEM TESTING

Note. In testing procedures, references to KOEO refer to Key On Engine Off. References to KOER are Key On Engine Running.

FUEL SYSTEM PRESSURE RELEASE

1. Remove fuel tank cap. Using Fuel Pressure Gauge (T80L-9974-B), release pressure from system at pressure relief valve (Schrader valve), located on fuel injection manifold rail.
2. If fuel pressure gauge is not available, disconnect electrical connector to inertia switch located on left side of luggage compartment. Remove fuel cap to release fuel tank pressure. Crank engine for 15 seconds to reduce system pressure.

FUEL DELIVERY

Note. For fuel system pressure testing and fuel pressure specifications, see the BASIC TESTING article.

Remove relay from vehicle. Connect battery voltage to terminal "C". Ground terminal "D". (Scheme 116) Measure resistance between terminals "A" and "B". Resistance should be less than one ohm with power applied and greater than 10 k/ohms with power removed.

FUEL PUMP TESTING

Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

Scheme 118

1. Visually inspect entire fuel delivery system for leaks, damaged or kinked lines and hoses. Ensure battery is fully charged and fuses are okay. Ensure adequate fuel is available in fuel tank. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE. Install fuel pressure gauge. With Key On Engine Off (KOEO) to activate pump, check and record fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(/ford/escort/v-1990-1992/remont/specifications/#fuel-pressure-specifications) article. Proceed to the appropriate step, as indicated: If fuel pressure is within specification, go to step 2. If fuel pressure is zero, go to step 5 If fuel pressure is low, go to step 11 If fuel pressure is high, go to step 12
2. Check fuel injectors. See FUEL INJECTORS. Crank or run vehicle. Using a mechanic's stethoscope, listen for regularly spaced operating sounds at each injector. If sound is present, check fuel injectors for flow and leakage. Clean or replace injectors as necessary.
3. If injector operating sound is not present, check fuel injector resistance. See FUEL INJECTORS. If injectors are not within specification, replace as necessary. If injectors are within specification, check injector electrical connections for continuity to ECA. If no continuity exists in circuit, check for 12 volts at each injector lead.
4. If voltage is not present at injectors, see Quick Test procedure in the appropriate TESTS W/CODES article. Faults in injector circuit should set a service code. If no service code has been set, see CIRCUIT TEST H, in the appropriate TESTS W/CODES article.
5. If fuel pressure is zero, ensure battery is fully charged and key is off. Ground fuel pump lead at SELF-TEST connector. Using a jumper lead, ground FP terminal. (Scheme 118) Ensure connection is okay at pump/sender unit. Turn key on, leaving engine off. Listen for sound of fuel pump. If pump is running, go to next step. If it is not running, go to step 7.
6. Check condition of high-pressure fuel filter. If filter is free of contamination check fuel pressure regulator, go to step 12. If filter is contaminated, replace filter and recheck system pressure as in step 1 procedure.
7. Turn key off and disconnect fuel pump/sender connector. Set DVOM on 200-ohm scale. Measure resistance between pump ground at connector and chassis ground. If resistance is greater than one ohm, repair open circuit to ground. If resistance is not greater than one ohm, go to next step.
8. Ensure key is off and battery is fully charged. Disconnect harness connector from pump/sender unit. Ground FP terminal at SELF-TEST connector. With KOEO and DVOM on 20-volt scale, measure voltage at Pump Power terminal of pump/sender connector. If voltage is greater than 10.5 volts, replace pump/sender assembly. If voltage is not as specified, go to next step.
9. With KOEO, check voltage at fuel pump inertia switch. If voltage is greater than 10.5 volts at both inertia switch terminals, repair wire between inertia switch and pump. If voltage is not as specified, reset or replace inertia switch as necessary and go to next step.
10. Ensure key is off and battery is fully charged. Ground FP terminal at SELF-TEST connector. With KOEO and DVOM on 20-volt scale, measure voltage at fuel pump relay (Brown wire). If voltage is greater than 10.5 volts at relay, repair Brown wire between fuel pump relay and inertia switch. If voltage is not as specified, check voltage supply to fuel pump relay and to terminal No. 1 at ECA. For additional circuit testing information see CIRCUIT TEST J in the TESTS W/CODES article.
11. Ground FP terminal at SELF-TEST connector. Using a DVOM, check voltage at fuel pump terminal (Pink/Black wire). If voltage at fuel pump is within.5 volt of battery voltage, go to step 6. If voltage is not as specified, go to step 5.
12. Check engine compartment for leaks and ensure engine produces normal engine vacuum. See FUEL PRESSURE REGULATOR test procedure.

Scheme 119

1. Ensure key is off. Connect fuel pressure gauge to Schrader valve on fuel rail. Ensure manifold vacuum supply tube is connected to fuel pressure regulator. Start and run engine for 10 seconds. Stop engine and wait 10 seconds. Start and operate engine for 10 seconds. Stop engine and remove pressure regulator vacuum hose. (Scheme 119) Check vacuum port for fuel.
2. If fuel is present, replace fuel pressure regulator and repeat test. If fuel is not present, start and run engine for 30 seconds. Stop engine and check fuel pressure gauge. If fuel pressure does not drop, go to step 4. If fuel pressure drops more than 5 psi (.4 kg/cm 2 ) in 60 seconds, disconnect and plug fuel return line at engine. Cycle ignition key on and off until normal fuel pressure is obtained.
3. Turn key off and check fuel pressure gauge. If gauge drops more than 5 psi (.4 kg/cm 2 ) in 30 seconds, replace high pressure fuel pump (dual pump system) or fuel sender/pump assembly (single pump type). If gauge does not drop more than 5 psi (.4 kg/cm 2 ) in 30 seconds, replace fuel pressure regulator.
4. Ensure key is off. Relieve fuel pressure. Remove fuel pressure regulator. Check "O" ring, gasket and mounting surfaces for cracks, cuts or other damage. Connect vacuum pump to fuel return tube and apply 20 in. Hg. If maximum vacuum loss exceeds 10 in. Hg in 10 seconds, replace regulator. If maximum vacuum loss does not exceed 10 in. Hg in 10 seconds, recheck entire fuel delivery system for cause of fuel pressure loss.

FUEL INJECTORS

1. Connect tachometer to engine. Run engine at idle. Disconnect and reconnect injectors individually. If each injector causes a momentary drop in engine speed of at least 100 RPM, injectors are giving proper fuel delivery. RPM drop should only be momentary as ISC will attempt to re-establish correct idle RPM.
2. Replace any injectors that do not cause sufficient drop in engine speed. When test is complete and all injectors cause equal drop in speed, shut off engine. In order to check curb idle, refer to emission control specifications on decal in engine compartment.

INJECTOR CIRCUIT

1. Disconnect all injector harness connectors. Using digital ohmmeter, check resistance across terminals of each injector. See appropriate injector resistance table.
2. On models without Sequential Electronic Fuel Injection (SEFI), disconnect injector bank harness connector, check resistance of injector bank. See INJECTOR BANK RESISTANCE table. Injectors on SEFI models have each individual injector wired to the ECA. Repair wiring or replace any injector circuit not within specification.

INDIVIDUAL INJECTOR RESISTANCE

IDLE CONTROL SYSTEM

Note. See Idle Air Control Valve (IAC) and Idle Speed Control Solenoid (ISC) test procedures under SOLENOIDS. Curb idle and fast idle speed is controlled by the ECA, and is not adjustable. Some throttle bodies have a sludge-tolerant design with a special coated throttle bore. A Yellow/Black warning decal on these units warns against backing off throttle plate adjustment screw to avoid throttle plate sticking in bore. Faults in idle control system components or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article.

IGNITION SYSTEMS

Note. For additional information and descriptions see IGNITION SYSTEMS in the THEORY & OPERATION article. Perform the Spark Output Check as outlined in the BASIC TESTING article before entering these tests. Some ignition systems require that Quick Test procedure be performed prior to testing. This will retrieve trouble codes from the EEC-IV system. See the TESTS W/CODES article in this section.

IGNITION SYSTEM ACRONYMS

IGNITION SYSTEM IDENTIFICATION

EDIS SYSTEM

Note. Start all diagnostics with the charts in TESTS W/O CODES article. Perform Quick Test procedure in TESTS W/CODES article before entering this test. These tests are dependent on results of the Quick Test procedure.

Note. The EDIS Diagnostic Cable (Rotunda 007-00059) should be used to diagnose this system. This cable is equipped with additional circuits and components used to enhance and modify signals for testing purposes. If an aftermarket test cable is used, or diagnosis is being performed using only a DVOM, ensure technician is familiar with system wiring diagram and system operation.

PRELIMINARY CHECK

Visually inspect the engine compartment to ensure all vacuum hoses and spark plug wires are properly and securely connected. Examine all wiring harnesses and connectors for damaged insulation, burned, overheated, damaged pins, loose or broken conditions. Check sensor shield connector. Ensure EDIS module mounting screw is tight. Ensure battery is fully charged and all accessories are off during diagnosis.

TEST EQUIPMENT

The following equipment should be used in these test procedures

1. EDIS Diagnostic Cable (Rotunda 007-00059)
2. Spark Tester (Neon Bulb Type)
3. Volt-Ohmmeter (Rotunda 007-00001)
4. Remote Starter Switch
5. 2 Breakout Boxes (BOB), for DIS (DIS BOB) and ECA (ECA BOB)
6. Spark Tester (D81P-6666-A or equivalent)
7. Inductive Timing Light
8. Test Light (LED type) or Logic Probe (LED type)

DIAGNOSTIC AIDS

When making measurements on a wiring harness, both a visual inspection and a continuity test should be performed. Inspect terminal connector pins for damage and corrosion, when directed to remove a connector.

1. Spark timing adjustments are not possible. Timing is controlled by the EDIS module with input from the ECA.
2. When checking voltage drop to GROUND, circuit must have a voltage drop of less than one volt.
3. Battery voltage (VBAT) is any voltage reading within 2 volts of actual battery voltage.
4. Spark timing will vary at idle due to feedback spark strategy used to control idle speed.
5. DO NOT connect positive lead of EDIS diagnostic cable to battery or connect cable to VR sensor until directed to.
6. SAW and IDM signal detectors in EDIS diagnostic cable will not work unless diagnostic cable battery leads are connected to battery.
7. When using DVOM to measure DC voltage always connect positive lead to BOB terminal A (+) and negative lead to A (-).

Note. A 12-volt incandescent (high voltage) test light SHOULD NOT be used to test circuit signals. It will load the circuit and may cause incorrect measurements or faulty EDIS/ECA operations (engine stall).

1.9L EDIS PINPOINT TEST INDEX

Note. (Scheme 120)- (Scheme 122) and the 1.9L EDIS SYSTEM PIN VOLTAGE SPECIFICATIONS for reference when using PINPOINT TEST procedures for the 1.9L EDIS system.

Scheme 120

Scheme 121

Scheme 122

1.9L EDIS SYSTEM PIN VOLTAGE SPECIFICATIONS

PINPOINT TEST A

PINPOINT TEST B

PINPOINT TEST C

PINPOINT TEST G

Note. The following test is written for DIS engines. The information is also applicable to EDIS engines.

Viewing Ignition System Secondary Display

Connect engine analyzer to view parade display of ignition system secondary. While slowly increasing engine speed from idle to 2000 RPM, compare engine analyzer display to illustrations. (Scheme 123) Illustrations shown are for a 4-cylinder engine but are typical.

1. An engine analyzer is used to diagnose problems in the secondary side of the ignition system.
2. Visually inspect the engine compartment to ensure all vacuum hoses and spark plug wires are properly routed and securely connected.
3. Examine all wiring harnesses and connectors for insulation damage, burned, overheated, loose or broken conditions.
4. Ensure battery is fully charged and all accessories are turned off during testing.
5. An engine analyzer or lab scope and DIS Adapter (Rotunda 007-00044) should be used in these testing procedures.

Note. If this portion of the diagnostic procedure is to provide accurate results, it is essential that the calibration of your engine analyzer be maintained. Refer to your equipment manual. If this is not available, an estimate of the calibration can be made by connecting the spark tester (D81P-6666-A or equivalent) to a properly operating ignition system and measuring the firing voltage of the spark tester only. Do not include the firing voltage of the rotor-to-cap gap. The spark tester firing voltage should be approximately 28 k/volts.

Scheme 123

PINPOINT TEST H

Note. Pin No. 7 (IGN GND OR IGND) is connected internally to the bottom 2 mounting holes at the base plate. This is the ignition ground circuit.

Air Supply Pump

Check belt tension and adjust to proper tension, if necessary. Disconnect air supply hose from by-pass control valve. Start engine. Pump is operating satisfactorily if airflow is felt at pump outlet and airflow increases as engine speed is increased. If this condition is not met, replace pump.

Air Silencer/Filter (Air Pump & Pulse Air Inlet)

Inspect hoses and air silencer for leaks. Disconnect hose from air silencer outlet. Remove silencer from vehicle and visually inspect for plugging. If no plugging or leaks are found, silencer is okay. If any plugging or leaks are found, repair or replace as required.

Scheme 124

1. Disconnect air supply hose at valve outlet. (Scheme 124) Remove vacuum line from vacuum nipple and check for presence of vacuum at nipple. There must be vacuum present at nipple before proceeding.
2. Reconnect vacuum line to vacuum nipple. With engine at 1500 RPM, air pump supply air should be heard and felt at air by-pass valve outlet.
3. With engine still at 1500 RPM, disconnect vacuum line. Air at outlet should decrease significantly or shut off. Air pump supply air should now be heard or felt at the silencer ports, or at the dump port.
4. If the normally closed air by-pass valve does not perform as described in steps 2 and 3, check the air pump for faults. If air pump is operating satisfactorily, replace air by-pass valve.

Air Check Valve

1. Visually inspect thermactor hoses, tubes, control valve(s) and check valve(s) for leaks that may be due to backflow of exhaust gases. If holes are found and/or traces of exhaust gas products are evident, check valve may be suspect.
2. Valve should allow free flow of air in direction of arrow only. (Scheme 125) The valve(s) should check (or block) the free flow of exhaust gas air in the opposite direction.
3. If air does not flow as indicated or if exhaust gas backflows opposite of direction of arrow in illustration, replace check valve.

Scheme 125

Scheme 126

1. Disconnect air supply hose at inlet. Accelerate engine to 1500 RPM and verify presence of airflow in hose. Reconnect air supply hose to valve inlet.
2. Disconnect air supply hoses at outlets "A" and "B". (Scheme 126) Remove vacuum line at vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "B" with little or no airflow at outlet "A".
3. Connect a vacuum line from manifold vacuum fitting to air supply control valve vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "A" with little or no airflow at outlet "B".
4. If valve does not meet above conditions, replace valve. If airflow operates as described in steps 1, 2 and 3, valve is okay. Reinstall hoses and clamps.

Scheme 127

1. Disconnect air supply hose at inlet. Accelerate engine to 1500 RPM and verify presence of airflow in hose. Reconnect air supply hose to valve inlet.
2. Carefully disconnect the air supply hoses at outlets "A" and "B". (Scheme 127) Carefully remove vacuum line at vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "B" with little or no airflow at outlet "A".
3. Connect a vacuum line from manifold vacuum fitting to air control valve vacuum nipple. Accelerate engine to 1500 RPM. Airflow should be heard and felt at outlet "A" with little or no airflow at outlet "B".
4. If the conditions in steps 2 and 3 are not met, replace the air control valve. If the valve operates satisfactorily, restore all hose and vacuum connections.

Air Pump Resonator

Visually inspect for holes. Remove hoses and check for restricted ports. Replace resonator if holes or ports are restricted. Reconnect hoses and install clamps.

Scheme 128

1. Disconnect hoses from outlets "A" and "B". (Scheme 128) Disconnect and plug vacuum line to port "D". With engine operating at 1500 RPM, airflow should be noted coming out of by-pass vents.
2. Reconnect vacuum line to port "D". Disconnect and plug vacuum line to port "S". Ensure vacuum is present in line to vacuum port "D". Accelerate engine to 1500 RPM. Airflow should be noted coming out of outlet "B". No airflow should be detected at outlet "A".
3. Apply 8-10 in. Hg vacuum to port "S". With engine operating at 1500 RPM, airflow should be noted coming out of outlet "A". If valve is bleed type, less air will flow from outlet "A" or "B", and the main discharge will change when vacuum is applied to port "S".
4. If the conditions in the above steps are not met, replace valve. If above conditions are met, valve is okay. Reconnect hoses and vacuum lines.

Dual Thermactor Air Control Solenoid Valve

The function of each valve can be determined by externally energizing the valve with vacuum lines attached. Check the resistance of each solenoid. Resistance should be 51-108 ohms when checked at the coil terminals. If the resistance is not 51-108 ohms, solenoid should be replaced.

Thermactor Idle Vacuum (TIV) Valve

1. With engine at idle and transmission in NEUTRAL, apply vacuum to small nipple and place fingers over the TIV valve atmospheric vent holes. (Scheme 129) If no vacuum is sensed, the TIV is damaged and must be replaced. If vacuum is sensed, go to next step.
2. With engine still at idle, apply vacuum to TIV valve large nipple from using a vacuum pump. See «TIV VALVE (LARGE NIPPLE) VACUUM SPECIFICATIONS»(/ford/escort/v-1990-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-19l). If vacuum is not held, the TIV is damaged and must be replaced. If no vacuum is sensed, replace valve.

Scheme 129

TIV VALVE (LARGE NIPPLE) VACUUM SPECS

Scheme 130

1. A 2-port valve may be in open or closed position when engine is cold, but should reverse when engine is warmed to operating temperature.
2. For 3-port valves, with a cold engine, passage "A" to "B" should be closed and passage "A" to "C" should be open. (Scheme 130) With engine at normal operating temperature, the VCV should be open between "A" and "B" and closed between "A" and "C".
3. For the 4-port valve, check "A1" to "B1" and "A2" to "B2" separately. (Scheme 131) A 4-port valve may be in open or closed position when engine is cold, but should reverse when engine is warmed to operating temperature. If these conditions are not met, replace the valve.

Scheme 131

1. Electrical vacuum control valve may be either open or closed at room temperature, but should reverse the position when engine is at full operating temperature. While engine is cold, measure continuity across switch terminals. (Scheme 131) Note if switch is open or closed.
2. Warm engine to normal operating temperature. Measure continuity across switch terminals again. Continuity should be opposite of cold condition. If switch continuity does not switch, replace valve. Check vacuum function of valve as described in VACUUM CONTROL VALVE above.

Vacuum Check Valve

Apply 16 in. Hg vacuum to check side of valve and trap. If vacuum remains greater than 15 in. Hg for 10 seconds, valve operation is normal. If vacuum drops faster, replace valve.

Vacuum Reservoir

When charged with 15-20 in. Hg vacuum, vacuum loss should not exceed 0.5 in. Hg in 60 seconds. If vacuum loss is faster, replace reservoir.

Pulse Air Valve

With engine at normal operating temperature and at curb idle, remove inlet hose from valve. A suction should be felt at valve inlet. If suction is not felt, replace valve.

Electronic EGR Valve (EEGR) & Pressure Feedback Electronic (PFE)

Note. EVR solenoid has a constant internal leak. You will notice a small vacuum signal of less than 1 in. Hg vacuum at idle.

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is less than 1 in. Hg vacuum to EGR valve at idle with engine at normal operating temperature.
2. Install tachometer. Disconnect Idle Air By-Pass Valve electrical connector (if equipped). Remove and plug vacuum hose at EGR valve. Start engine and idle in neutral. Note idle speed. Using hand vacuum pump, slowly apply 5-10 in. Hg vacuum to EGR valve. When vacuum is fully applied to EGR valve, engine should do one or more of the following: Engine should stall Idle speed should drop more than 100 RPM Idle speed should return to normal when vacuum is released
3. Repair or replace EGR valve if none of the above occurs. Reconnect idle air by-pass valve electrical connector. Unplug and reconnect vacuum hose at EGR valve.

EGR Vacuum Regulator (EVR)

Faults in EVR or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DN in TESTS W/CODES article for diagnostic procedures.

EGR Solenoid

Remove EGR solenoid harness connector. Measure resistance across solenoid terminals. Resistance should be 65-110 ohms. Set DVOM to 200-k/ohm scale. Measure resistance between each solenoid terminal and ground or side of solenoid. Resistance should be greater than 10 k/ohms. If resistance is not as specified in either test, replace solenoid.

Differential Pressure Feedback Electronic (DPFE) Transducer

Faults in DPFE transducer or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DL in the TESTS W/CODES article for diagnostic procedures.

Pressure Feedback Electronic (PFE) Transducer

Faults in PFE transducer or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST DL in the appropriate TESTS W/CODES article for diagnostic procedures.

Apply 16 in. Hg vacuum to check side of valve and trap. If vacuum remains greater than 15 in. Hg for 10 seconds, valve operation is normal. If not, replace valve.

When charged with 15-20 in. Hg vacuum, vacuum loss should not exceed 0.5 in. Hg in 60 seconds. If it does, replace reservoir.

Canister Purge Regulator (CPR) Valve

With CPR valve de-energized, apply 5 in. Hg vacuum to source port. Valve should not pass air. Apply 9-14 volts to one electrical terminal and ground the other. Valve should open and pass air. If valve does not operate as described, replace valve.

Canister Purge (CANP) Solenoid

Faults in CANP solenoid or circuit should set a service code. See Quick Test procedure in the appropriate TESTS W/CODES article. If no service code has been set, see CIRCUIT TEST KD in the appropriate TESTS W/CODES article for diagnostic procedures.

EVAP Canister

There are no moving parts in canister. Check for loose, missing, cracked or broken connections or parts. Repair or replace as necessary. There should be no liquid in canister.

PCV Valve

1. Remove PCV valve from rocker cover grommet. Shake valve. Valve should rattle when shaken. If valve does not rattle, replace valve.
2. Start engine and warm to normal operating temperature.
3. Disconnect hose from remote air cleaner or outlet tube. Place stiff piece of paper over hose end and wait 60 seconds. Vacuum should hold paper in place. If vacuum does not hold paper in place, replace valve.

Air Cleaner Temperature Sensor

Bring temperature of sensor below 75°F and apply 8 in. Hg vacuum to source port. Duct door should close. If door does not close, replace sensor. Sensor will bleed off vacuum to allow duct door to open and let in fresh air at specific temperatures. See AIR CLEANER TEMPERATURE SENSOR OPENING .

AIR CLEANER TEMPERATURE SENSOR OPENING

Air Control Door

When a vacuum of 8 in. Hg or more is applied to vacuum motor, door should stay in proper position for as long as vacuum is applied. If vacuum bleeds off and door returns to rest position, replace vacuum motor.

Wiring Diagram (1.9L PFI Escort & Tracer EEC-IV). Scheme 132

See also:
• FUEL PRESSURE SPECIFICATIONS
• WIRING DIAGRAMS