Engine Controls - System/component Tests - Eec-Iv Mercury Topaz II

INTRODUCTION

Prior to testing separate components or systems, it is highly recommended that all of the procedures listed in the F - BASIS TESTING article be performed. Since many computer controlled and monitored components will set a trouble code if they malfunction, it is also recommended that self-diagnosis be performed. See TESTS W/CODES article in this section.

Note. Testing of individual components does not isolate possible shorts or opens in the vehicle harness of electronically controlled systems. Use an ohmmeter to isolate shorts or opens in harness. All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated different in testing procedures.

SUPERCHARGER CHECK

Note. The supercharger cannot be rebuilt or overhauled. If supercharger malfunctions, it will be necessary to replace entire supercharger assembly.

BOOST PRESSURE CHECK

1. With engine cool, disconnect air hose from turbo boost control solenoid valve on turbocharger. Connect vacuum/pressure gauge to control solenoid.
2. Start engine and allow it to warm-up to normal operating temperature. Increase engine speed to 4000 RPM. If gauge reads any positive pressure above zero, perform OVERBOOST WARNING CHIME CHECK. If gauge does not read any positive pressure above zero, perform TURBO BOOST CONTROL SOLENOID VALVE CHECK.

OVERBOOST WARNING CHIME CHECK

1. Start the engine and run at 2000 RPM. Remove the air filter upper housing. Push measuring plate of vane airflow meter to fully open position.
2. Ensure warning buzzer sounds and engine speed drops or engine stalls. If not, see appropriate TESTS W/CODES article in this section. Turn off engine and replace air filter upper housing.

COMPRESSOR BY-PASS VALVE FUNCTION CHECK

With compressor by-pass valve removed from the vehicle, apply a vacuum of 9.8-15.7 in. Hg to small port of the valve. Blow through large port to verify air flows. If air does not flow, replace compressor by-pass valve.

TURBO BOOST CONTROL SOLENOID VALVE CHECK

1. Remove small air tube from turbocharger inlet air hose. Disconnect turbo boost control solenoid valve electrical connector.
2. Blow through small air tube and ensure air will not flow. Apply 12 volts to one terminal of the electrical connector and ground the other terminal.
3. Blow through the air tube and ensure that air flows through the tube. If solenoid valve does not pass test, replace solenoid valve.

INTAKE AIR VALVE DIAPHRAGMS

With engine off, disconnect vacuum lines from both intake air valves. Apply 10 in. Hg vacuum to each intake air valves. Replace air valves if they will not hold vacuum.

IAC SOLENOID

With engine off, wait 10 seconds and disconnect Intake Air Control (IAC) solenoid. Solenoid is mounted on center of firewall. Using an ohmmeter on 200 ohm scale, check resistance between IAC solenoid terminals. Resistance should be between 50-100 ohms. If resistance is not as specified, replace solenoid.

GROUND CIRCUITS

1. Using an ohmmeter, check for continuity to ground on ECU terminals 40 and 60 on all models except Probe 2.2L. On Probe 2.2L models check ECA terminals 3A, 3B and 3C (2A, 2B and 2C with non-turbo, manual transmission). Resistance should be zero ohms. If not, repair open to ground.
2. Using a DVOM, touch negative lead of voltmeter to a good ground. Touch positive lead of voltmeter to each ground terminal. With vehicle running, voltmeter should indicate less than 1 volt. If voltmeter reading is greater than 1 volt, check for open, corrosion or loose connection on ground lead.

POWER CIRCUITS

Using a voltmeter, check for battery voltage between ECU terminal 1 and ground on all models except Probe 2.2L. On Probe with 2.2L, check for battery voltage at ECA terminal 1B. If battery voltage is not present, check Blue fusible link. If fusible link is okay, check for an open in wire to terminal No. 1 on control unit.

AIR CHARGE TEMPERATURE (ACT) SENSOR TEST

Disconnect suspect temperature sensor. Set DVOM to 200 k/ohm scale. Measure resistance between sensor terminals. Refer to TEMPERATURE SENSOR VOLTAGE & RESISTANCE table under VAT Sensor in this article for resistance specifications.

BAROMETRIC PRESSURE SENSOR TEST (2.2L PROBE)

Faults in barometric pressure sensor circuit should set a trouble code. If a code 14 exists, refer to Code 14 in the TESTS W/CODES article in this section.

CRANKSHAFT POSITION SENSOR (CPS) TEST

Disconnect distributor connector. Measure resistance across CPS sensor terminals. Resistance readings should be 210-250 ohms. If resistance values are not within specifications, replace CPS.

CYLINDER ID SENSORS TEST (2.2L PROBE TURBO ONLY)

Disconnect distributor connector. Measure resistance between distributor connector terminals CID1 and CID REF. (Scheme 100) Resistance readings should be between 210-260 ohms. If sensor values are not within specifications, replace sensor(s).

Scheme 100

ENGINE COOLANT TEMPERATURE (ECT) SENSOR TEST

Disconnect suspect temperature sensor. Set DVOM to 200 k/ohm scale. Measure resistance between sensor terminals. Refer to ECT & ACT TEMPERATURE SENSORS VOLTAGE & RESISTANCE SPECIFICATIONS (EXCEPT PROBE 2.2L) table for voltage and resistance specifications for all models except Probe with 2.2L. Refer to ECT & VAT TEMPERATURE SENSORS VOLTAGE & RESISTANCE SPECIFICATIONS (PROBE 2.2L) table for voltage and resistance specifications for Probe models with 2.2L. (Scheme 101)

ECT & ACT TEMP SENSORS VOLTAGE & RESISTANCE SPECS (EXCEPT PROBE 2.2L)

ECT & VAT TEMP SENSORS VOLTAGE & RESISTANCE SPECS (PROBE 2.2L)

Scheme 101

EGR VALVE POSITION (EVP) SENSOR (2.2L PROBE CALIF. ONLY)

Connect vacuum pump to EGR valve vacuum port. Backprobe EVP sensor VREF (Light Green/Red) and SIGRTN (Light Green/Yellow) wires. Turn ignition switch to RUN position. Compare readings. See EVP SENSOR VOLTAGE table. (Scheme 102)

Scheme 102

EVP SENSOR VOLTAGE

HEATED GAS OXYGEN (HEGO) SENSOR TEST

Disconnect oxygen sensor connector. Measure voltage between oxygen sensor wire and ground. At idle voltage reading should be 0.2-0.8 volts. Increasing engine speed increases oxygen sensor voltage and decreasing engine speed decreases oxygen sensor voltage. Replace if out of specification.

INERTIA SWITCH TEST

Push down on reset button to make sure switch is closed. With fuel pump running, use DVOM to measure voltage across both terminals of inertia switch. If voltage is greater than 0.3 volts, replace inertia switch.

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

On Crown Victoria and Grand Marquis station wagon models, switch is located in left rear side storage compartment. On Mustang, it is located near left taillight. On Taurus and Sable station wagon models, switch is located behind access door in right rear cargo area. On all other vehicles, inertia switch is located in trunk, on left hinge support or behind trim panel.

KNOCK SENSOR TEST (EXCEPT 2.2L PROBE TURBO)

Locate sensor and remove harness connector. Set DVOM to 200 ohm scale. Measure resistance across sensor terminals. Resistance should be greater than 10 k/ohms. If resistance is less than 10 k/ohms, replace sensor.

KNOCK SENSOR TEST (2.2L PROBE TURBO)

Disconnect knock control sensor connector. Knock sensor is located on right side of engine, next to oil filter. Using DVOM with scale set to AC volts, measure AC voltage between KS wire on sensor and ground. Using a 4 oz. hammer tap on engine lifting eye lightly. Voltage reading should be approximately .03 volts. If below specification, replace knock sensor.

MAP/BP SENSOR TEST

Remove vacuum supply hose. Install vacuum pump to sensor and apply 18 in. Hg vacuum. Sensor should hold vacuum. If sensor does not hold vacuum, replace sensor. For more testing information refer to TESTS W/CODES article in this section.

MASS AIRFLOW (MA) SENSOR TEST

See TESTS W/CODES article in this section.

NEUTRAL DRIVE SWITCH (NDS) A/C INPUT TEST

Key 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 the clutch pedal down. If each resistance value is more than 5 ohms, switches are open. Replace switches.

POWER STEERING PRESSURE SWITCH (PSPS) TEST

1. Disconnect PSPS connector at steering gear box. Set DVOM to 200-ohm scale. Turn ignition switch to ON position. Measure resistance across PSPS terminals. Ohmmeter should indicate less than 10 ohms resistance between key on engine off and engine running.
2. With engine running, turn steering wheel at least one-half turn then return. Resistance should change from less than 10 ohms to infinity (indicating PSPS opening), then returning to 10 ohms or less when steering wheel is returned to center position.

THROTTLE POSITION SENSOR TEST (2.2L PROBE)

For throttle position switch specifications and adjustment procedures, see the ADJUSTMENTS article in this section.

TRANSMISSION TORQUE CONVERTER SPEED (TCS) SENSOR (2.2L PROBE)

Disconnect transmission torque converter sensor connector. Connector has Yellow/Green and Yellow/Blue wires. Measure resistance across TCS sensor terminals. Resistance reading should be 210-260 ohms. If resistance value is not within specification, replace TCS sensor.

VANE AIR FLOW TEMPERATURE (VAT) SENSOR (2.2L PROBE)

When testing VAT sensor, ensure ambient temperature is greater than 50° F. Disconnect suspect temperature sensor. Set DVOM to 20 k/ohm scale. Measure resistance between sensor terminals. Refer to VAT SENSOR VOLTAGE & RESISTANCE SPECS (PROBE 2.2L) table for voltage and resistance specifications. see scheme 4

VAT SENSORS VOLTAGE & RESISTANCE SPECS (PROBE 2.2L)

VANE AIR FLOW METER TEST (2.2L PROBE)

Ensure air passages are clean and free of oil film buildup. DO NOT spray cleaner inside Vane Air Flow Meter. For trouble shooting, see TESTS W/CODES article in this section.

VEHICLE SPEED SENSOR (VSS) TEST

Disconnect speed sensor electrical connector. Using DVOM check resistance across sensor terminals. Resistance should be 200-300 ohms. Raise vehicle on hoist. Set DVOM to AC volts and connect across sensor terminals. Operate vehicle on hoist, or road test at approximately 20 MPH and observe DVOM. Voltage should be 1.5-6.5 volts AC.

COLD START RELAY

See FUEL CONTROL under FUEL SYSTEM TESTS in this article.

FUEL PUMP RELAY

Remove relay from vehicle. Connect battery voltage to terminal "C". Ground terminal "D". (Scheme 103) 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 103

HOT START PULSE RELAY

See FUEL DELIVERY under FUEL SYSTEM TESTS in this article.

EFE RELAY

See appropriate EMISSIONS/SUB-SYSTEMS in this article.

AIR INJECTION CONTROL SOLENOID

See appropriate EMISSIONS/SUB-SYSTEMS in this article.

AIR MANAGEMENT SOLENOIDS (AM1/AM2)

Disconnect solenoid harness connectors and measure resistance across terminals. Resistance should be 50-100 ohms. If resistance is not as specified, replace solenoid.

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 of vacuum to manifold vacuum side of solenoid. CANP solenoid should hold vacuum for 20 seconds.

EGR SOLENOID

See appropriate EMISSIONS/SUB-SYSTEMS in this article.

Ensure ignition is off. Disconnect solenoid harness connector. Set DVOM to 200 ohm scale. Measure resistance between solenoid terminals. Resistance should be 50-100 ohms. Set DVOM to 20 k/ohm scale. Measure resistance between each IAC solenoid terminal and solenoid case. Resistance should be greater than 100 k/ohms. If resistance in either test is not as specified, replace solenoid.

ISC SOLENOID

1. Ensure ignition is off. Disconnect ISC solenoid harness connector. Set DVOM to 200-ohm scale. Measure resistance between ISC solenoid terminals. Due to diode in solenoid, resistance should be higher in one direction than other. If resistance is 7-13 ohms in one direction and higher in other direction, solenoid is okay.
2. Set DVOM to 20 k/ohm scale. Measure resistance from either ISC solenoid terminal to ISC solenoid housing. If resistance is greater than 10 k/ohms, ISC solenoid is okay.

TURBO BOOST CONTROL SOLENOID

See TURBO BOOST CONTROL SOLENOID VALVE CHECK under TURBOCHARGER CHECKS in this article.

TFI-IV MODULE

1. Remove distributor from engine and remove TFI module from distributor. Measure resistance between TFI-IV module terminals. See «TFI-IV MODULE RESISTANCE»(/mercury/topaz/ii-1987-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-eec-iv) table. (Scheme 104)
2. If resistance measurements agree with table, replace stator. If resistance measurements are NOT as specified, replace TFI-IV module.

TFI-IV MODULE RESISTANCE

Scheme 104

TFI-IV CLOSED BOWL STATOR CHECK

1. Separate wiring harness connector from distributor. Measure resistance between stator connector terminals No. 1 and 5. Resistance between terminals No. 1 and 5 should be less than 5 ohms. (Scheme 105)
2. Measure resistance between stator connector terminal No. 2 and ground. Measure resistance between stator connector terminal No. 6 and ground. Resistance should be less than one ohm in both cases.

Scheme 105

2.2L & 2.2L Turbo

Relieve fuel line pressure by starting engine and disconnecting fuel pump relay. After engine stalls turn ignition off. Reconnect fuel pump relay.

All Other Models

Remove fuel tank cap. Using Fuel Pressure Gauge (T80L-9974-B), release pressure from system at pressure relief valve (Schrader valve) on fuel injection manifold rail.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC TESTING article in this section.

FUEL PRESSURE REGULATOR

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

1. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEM TESTS in this article. Connect fuel pressure gauge at Schrader valve. Start and operate engine for 10 seconds. Stop engine for 10 seconds. Start and operate engine for 10 seconds. Stop engine and remove pressure regulator vacuum hose. Check vacuum port for fuel.
2. If fuel is present, replace fuel pressure regulator. If not, start and operate engine for 30 seconds. Stop engine and check fuel pressure gauge. If gauge drops more than 5 psi in 60 seconds, disconnect and plug fuel return line at engine. Start and operate engine until normal fuel pressure is obtained.
3. Stop engine and check fuel pressure gauge. If gauge drops more than 5 psi 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 in 30 seconds, replace fuel pressure regulator.

Remove relay from vehicle. Connect battery voltage to terminal "C". Ground terminal "D". see scheme 8 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 INJECTORS (PFI)

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 PFI models, disconnect injector bank harness connector, check resistance of injector bank. See «PFI INJECTOR BANK RESISTANCE»(/mercury/topaz/ii-1987-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-eec-iv) table. Repair wiring or replace any injector circuit not within specification.

PFI INDIVIDUAL INJECTOR RESISTANCE

PFI INJECTOR BANK RESISTANCE

SINGLE INJECTOR RESISTANCE

Note. For further component testing and information, see appropriate TESTS W/CODES article in this section.

IDLE CONTROL SYSTEM TESTS

Note. If idle RPM is not correct after performing these procedures, see appropriate TESTS W/CODES article in this section.

FBCA MOTOR (5.8L V8 MCU)

1. Remove FBCA motor from carburetor. Connect wiring harness to FBCA motor. Turn ignition on. Motor shaft should extend.
2. Turn ignition off. If shaft does not extend, replace motor. Push FBCA motor shaft back in by hand. If shaft will not push in, replace FBCA motor.

ISC MOTOR (CFI)

1. Turn key off and wait 10 seconds. Disconnect harness from DC motor. Using jumper wires, connect ISC positive (+) circuit of DC motor to battery positive (+) terminal. Connect ISC negative (-) circuit of DC motor to battery negative terminal for 4 seconds.
2. Motor shaft should extend more than 2" (51 mm). Connect ISC (+) circuit of DC motor to battery negative terminal and ISC (-) circuit of DC motor to battery positive terminal for 4 seconds. Motor shaft should retract to less than 1 3/4" (44 mm). If motor shaft does not move in and out as indicated, replace DC motor.

ISC MOTOR (MPI)

1. Turn key off and wait 10 seconds. Disconnect harness from ISC motor. Using ohmmeter, put positive lead on ISC connector VPWR terminal and negative lead on ISC terminal. Resistance should be 7-13 ohms. If not, replace ISC motor.
2. If resistance is 7-13 ohms, measure resistance between either ISC connector terminal and ISC housing. Resistance should be greater than 10 k/ohms. If not, replace ISC motor. If resistance is greater than 10 k/ohms, go to step 3).
3. Turn ignition on. Using a voltmeter, measure voltage between ISC connector terminals. If voltage is less than 10.5 volts, repair open circuit and repeat test. If voltage is greater than 10.5 volts, turn ignition off. With ISC connector disengaged, connect Breakout Box (014-00322) and leave processor disconnected.
4. Measure resistance between breakout box test pin No. 21 and ISC terminal on ISC connector. If resistance is greater than 5 ohms, repair open circuit and repeat test. If resistance is less than 5 ohms, measure resistance between breakout box test pin No. 21 and the following test pins: 40, 46, and 60. If resistance is less than 10 k/ohms, repair short circuit and repeat test.

CHOKE CAP CONTINUITY

1. With ignition off, connect a test light between battery positive terminal and choke cap terminal. Test light should light, indicating continuity. If test light is on, perform appropriate CIRCUIT CONTINUITY test.
2. If test light is not on, connect a jumper wire between choke cap clamp shroud and battery negative terminal. Connect test light between battery positive terminal and choke cap terminal. If test light is on, replace choke cap.
3. If test light is not on, connect a jumper wire directly to choke cap ground. If test light is on, correct poor contact between choke cap clamp shroud and choke cap ground.

CIRCUIT CONTINUITY (ALTERNATOR-POWERED CHOKE)

Connect test light between choke cap ground and battery negative terminal. Start engine. Test light should be on. If test light is not on, locate and repair open circuit between choke cap and alternator stator terminal. If no open in circuit is found, check alternator output.

CIRCUIT CONTINUITY (BATTERY-POWERED CHOKE)

1. With engine and ignition off, disconnect oil pressure switch from harness. Using a jumper wire in place of switch, complete choke circuit. Connect test light between battery negative terminal and choke cap terminal.
2. Turn ignition on, but do not start engine. Test light should be on, indicating continuity. If test light is not on, locate and repair open circuit. Turn ignition off. Check fuse, fusible link, wiring and connectors in choke circuit.
3. Remove jumper wire and connect harness to oil pressure switch. Turn ignition on, but do not start engine. Test light should be off. If test light is on, replace oil pressure switch. Start engine. Test light should be on. If test light is not on, replace oil pressure switch.

IGNITION SYSTEM CHECKS

Note. For basic ignition checks, see BASIC TESTING article in this section.

TIMING CONTROL SYSTEMS TESTS

For timing specifications, see BASIC TESTING article in this section. For timing adjustment procedure, see ADJUSTMENTS article in this section. For timing control system test procedures, see TESTS W/CODES article in this section.

AIR SUPPLY PUMP

Check belt tension and adjust to proper tension, if necessary. Disconnect air supply hose from bypass 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 AND 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.

AIR BYPASS VALVE (NORMALLY CLOSED)

1. Disconnect air supply hose at valve outlet. (Scheme 106) 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 bypass valve.

Scheme 106

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 107) 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 107

AIR SUPPLY CONTROL VALVE

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 108) 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 108

AIR CONTROL VALVE (SWITCH-RELIEF)

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 109) 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.

Scheme 109

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.

COMBINATION AIR BY-PASS/AIR CONTROL VALVE

1. Disconnect hoses from outlets "A" and "B". (Scheme 110) 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.

Scheme 110

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 between 51-108 ohms when checked at the coil terminals. If the resistance is not within these values, solenoid should be replaced.

SOLENOID VACUUM VALVE ASSEMBLY

The ports should flow air when the solenoid is energized. The solenoid resistance at the terminals should be between 51-108 ohms. If the solenoid resistance is not within this range, replace the solenoid.

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 111) 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 SPECIFICATION»(/mercury/topaz/ii-1987-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-eec-iv) table. If vacuum is not held, the TIV is damaged and must be replaced. If no vacuum is sensed, replace valve.

Scheme 111

TIV VALVE (LARGE NIPPLE) VACUUM SPECS

VACUUM CONTROL VALVE (VCV)

1. 2-port valves may be in open or closed position when engine is cold. 2-port valves 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 112) 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 112) 4-port valves may be in open or closed position when engine is cold. 4-port valves should reverse when engine is warmed to operating temperature. If these conditions are not met, replace the valve.

Scheme 112

ELECTRICAL VACUUM CONTROL VALVE

1. Electrical vacuum control valve may be either opened or closed at room temperature. It should be reversed (opened to closed or closed to opened) with engine at full operating temperature. While engine is cold, measure continuity across switch terminals. (Scheme 113) 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.

Scheme 113

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 not, replace valve.

VACUUM RESERVOIR

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

PULSE AIR VALVE

With engine at normal operating temperature and at curb idle, a suction should be felt at valve inlet. If not, replace valve.

BACKPRESSURE VARIABLE TRANSDUCER (BVT) SYSTEM

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is no vacuum to EGR valve at idle. Install tachometer. Disconnect idle air bypass valve electrical connector (if equipped). Remove and plug vacuum hose from EGR valve.
2. Start engine and idle in neutral. Note idle speed. Using hand vacuum pump, slowly apply 5-10 in. Hg of vacuum to EGR valve. When vacuum is fully applied to EGR valve: If idle speed drops more than 100 RPM or if engine stalls, perform next step. If idle speed does not drop, replace EGR valve. If EGR passages are blocked, clean EGR valve. Remove vacuum from EGR valve. If idle speed does not return to normal, check for contamination, clean valve. If symptom still exists, replace EGR valve
3. Reconnect idle air by-pass valve electrical connector. Unplug and reconnect EGR vacuum hose. Disconnect vacuum hose at BVT. Gently blow into hose to port "C" until relief valve closes and at same time apply 5-10 in. Hg of vacuum to port E. (Scheme 114) Port "E" should hold vacuum as long as pressure is applied to port "C".
4. Apply 5-10 in. Hg of vacuum to ports "B" and "C". Both ports should hold vacuum. Replace BVT if any port fails to hold vacuum.

Scheme 114

ELECTRONIC EGR VALVE (EEGR)

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is less than 2.5 in. Hg of vacuum to EGR valve at idle with engine at normal operating temperature. NOTE: EVR solenoid has a constant internal leak. You will notice a small vacuum signal of less than 1.0 in. Hg of vacuum at idle.
2. Install tachometer. Disconnect idle air by-pass valve electrical connector (1.9L CFI engines only). 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 of 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.

Remove EGR solenoid harness connector. Measure resistance across solenoid terminals. Resistance should be 65-110 ohms. Set DVOM to 200k-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.

INTEGRAL BACKPRESSURE (IBP) TRANSDUCER EGR VALVE

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is no vacuum to EGR valve at idle. Install tachometer. Plug tailpipe(s), leaving 1/2" diameter opening to allow exhaust to escape. Remove and plug vacuum supply hose from EGR valve.
2. Start engine and idle in neutral. Note idle speed. Using hand vacuum pump, slowly apply 5-10 in. Hg of vacuum 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. 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 VALVE (PORTED)

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is no vacuum to EGR valve at idle. Install tachometer. Disconnect idle air by-pass valve electrical connector (EFI only). Remove and plug vacuum hose from EGR valve.
2. Start engine and idle in neutral. Note idle speed. Using hand vacuum pump, slowly apply 5-10 in. Hg of vacuum to EGR valve. When vacuum is fully applied to EGR valve: If idle speed drops more than 100 RPM or if engine stalls, perform next step. If idle speed does not drop, replace EGR valve. If EGR passages are blocked, clean EGR valve. Remove vacuum from EGR valve. If idle speed does not return to normal, check for contamination, clean valve. Ensure no contamination or debris is left in valve or pick-up tube. Replace valve if necessary.
3. Unplug reconnect EGR vacuum hose. Reconnect idle air bypass electrical connector.

CANISTER PURGE REGULATOR (CPR) VALVE

With CPR valve de-energized, apply 5 in. Hg of 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.

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.

FUEL BOWL THERMAL VENT VALVE

Fill container with water. Monitor water temperature with thermometer. Submerse valve in water for one to two minutes and try to pull air through valve with hand vacuum pump. At 90°F (32°C) and below, valve should be fully closed. At 120°F (49°C) and above, valve should be fully open. At temperatures between 90-120°F (32-49°C), valve may be open or closed.

FUEL BOWL VENT SOLENOID VALVE

Apply 9-14 volts to one solenoid electrical connector and ground other. Valve should close. If valve does not close, or if valve leaks, when voltage and one in. Hg of vacuum is applied to carburetor port, replace valve.

VACUUM BOWL VENT VALVE

Valve should flow air between carburetor port and canister port when no vacuum is applied to signal port and should not flow air with vacuum applied to signal port.

VACUUM/THERMOSTATIC BOWL VENT VALVE

At temperature of 120°F (49°C) or more, valve should flow air between carburetor port and canister port when no vacuum is applied to vacuum signal port. It should not flow air with vacuum applied to signal port. At temperature of 90°F (32°C) or less, valve should not flow air or be very restrictive to air flow.

PCV VALVE (ALL EXCEPT 1.9L CFI)

1. Remove PCV valve from rocker cover grommet. Shake valve. Valve should rattle when shaken. Start engine to normal operating temperature. On models with 2.3L HSC and 2.5L, remove corrugated hose from oil separator nipple. Place stiff piece of paper over nipple end and wait one minute.
2. On all other models, disconnect hose from remote air cleaner. Place stiff piece of paper over hose end and wait one minute. Vacuum should hold paper in place. If not replace valve.

PCV VALVE (1.9L CFI)

1. Remove vacuum control hose at dual orifice valve (located at throttle body port). Apply manifold vacuum to port. There should be a significant change in engine RPM. If no RPM change, replace dual orifice valve assembly.
2. Remove crankcase vent connector from side of air cleaner. Place stiff piece of paper over crankcase vent connector nipple. Vacuum should hold paper in place for one minute.
3. Remove vacuum hose (small port) at crankcase vent connector. Place stiff piece of paper over vacuum hose. Vacuum should hold paper in place for one minute. If not, replace crankcase vent connector.
4. Remove dual orifice valve assembly from system. Inspect for blockage through valve. If blocked, replace valve.

AIR CLEANER TEMPERATURE SENSOR

Bring temperature of sensor to below 75°F and apply 8 in. Hg of vacuum to source port. Duct door should close. If not, 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 table.

AIR CLEANER TEMPERATURE SENSOR OPENING

COLD WEATHER MODULATOR

Hold modulator in closed palm of hand for about 15 minutes. Apply 16 in. Hg of vacuum to supply port of modulator. Compare with COLD WEATHER MODULATOR chart. Place modulator in container of ice water for 30-40 minutes. Apply 16 in. Hg of vacuum to supply port of modulator. See COLD WEATHER MODULATOR SPECIFICATIONS table.

COLD WEATHER MODULATOR SPECIFICATIONS

AIR CONTROL DOOR

When a vacuum of 8 in. Hg or more is applied to vacuum motor, door should stay up as long as vacuum is applied.

Apply 16 in. Hg of vacuum to CHECK side of valve and trap. If vacuum remains above 15 in. Hg for 10 seconds, valve is good.

VACUUM DELAY VALVE (VDV)

Connect hand vacuum pump to VDV. Valves with one side BLACK or WHITE and other side colored are good if vacuum can be built-up in one direction, but not the other direction and if built-up vacuum slowly decreases. Valves with both sides the same color are good if vacuum can be built-up in both directions before visibly decreasing.

VACUUM RESTRICTOR

Orifice type flow restrictor is used in emission calibrations to control flow rate and/or timing inactions. Restrictor can be found in EGR valve system (opening and closing), part throttle spark advance, purge system and thermactor system. Flow rate through restrictor is same in both directions. If blocked, replace restrictor.

VACUUM RESTRICTOR IDENTIFICATION

See also:
• FUEL PRESSURE SPECIFICATIONS
• ECT & ACT TEMPERATURE SENSORS VOLTAGE & RESISTANCE SPECIFICATIONS (EXCEPT PROBE 2.2L)