Engine Controls - System/component Tests 4.6l Lincoln Mark VIII I

INTRODUCTION

Before testing separate components or systems, perform procedures in the BASIC TESTING - 4.6L article. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in the appropriate TESTS W/CODES - EEC-IV article.

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

Note. For wiring diagrams not shown in testing procedures, see appropriate wiring diagram in the WIRING DIAGRAMS article in the ENGINE PERFORMANCE section.

Note. In following tests, circuit diagrams and illustrations are courtesy of Ford Motor Co.

Intake Manifold Runner Control Valve

With engine off, disconnect vacuum lines from both intake air valves. Apply 10 in. Hg vacuum to each air valve. Replace air valves if linkage does not respond and/or vacuum is not held.

Intake Air Control Solenoid

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

Ground Circuits

1. Using a DVOM, check resistance to ground on PCM terminals No. 40 and 60. (Scheme 1) Resistance should be zero ohms. If resistance is not zero ohms, 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, voltmeter should indicate less than 0.5 volt. If voltmeter reading is greater than 0.5 volt, check for open circuit, corrosion and loose connection on ground lead.

Power Circuits

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

PCM Connector Terminal Identification. Scheme 1

ENGINE SENSORS & SWITCHES

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

A/C CUTOUT

Faults in system or circuits should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, See CIRCUIT TEST KM in the same article for testing.

BAROMETRIC PRESSURE (BARO) SENSOR

Faults in barometric pressure sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the appropriate TESTS W/CODES - EEC-IV article. If code has not been set, see CIRCUIT TEST DF in same article for sensor specifications.

CYLINDER IDENTIFICATION (CID)

CID is integral with Camshaft Position (CMP) sensor or Crankshaft Position (CKP) sensor. Disconnect sensor connector. See CID SENSOR LOCATION table. Check connector for wear or corrosion. For additional circuit testing information, see CIRCUIT TEST DR in the TESTS W/CODES - EEC-IV article and also in the PIN VOLTAGE CHARTS article.

CID SENSOR LOCATION (1)

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

ECT sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, check resistance between sensor terminals. For specifications, see the SENSOR RANGE CHARTS article. For additional sensor circuit testing, see CIRCUIT TEST DA in the TESTS W/CODES - EEC-IV article.

EGR ATMOSPHERIC (EGRA) SOLENOID

Faults in sensor or circuit should set a diagnostic trouble code. If diagnostic trouble code has not been set, disconnect sensor. Measure resistance between sensor terminals. Replace sensor if resistance is not 30-70 ohms.

EGR POSITION (EGRP) SENSOR

Faults in sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST DD in the same article for testing.

EGR VACUUM REGULATOR (EVR) SOLENOID

Faults in sensor or circuit should set a diagnostic trouble code. If diagnostic trouble code has not been set, disconnect sensor. Measure resistance between sensor terminals. Replace sensor if resistance is not 20-70 ohms.

EGR VACUUM (EGRV) SOLENOID

Faults in sensor or circuit should set a diagnostic trouble code. If diagnostic trouble code has not been set, disconnect sensor. Measure resistance between sensor terminals. Replace sensor if resistance is not 30-70 ohms.

EGR VALVE POSITION (EVP) SENSOR

Faults in sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST DN in the same article for testing.

HEATED GAS OXYGEN SENSOR (HO2S)

Vehicle may be equipped with one or 2 HO2S sensors. They are located in exhaust pipe, upstream of catalytic converters. Faults in sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, ensure none of these conditions exist

1. Moisture inside sensor/harness connector.
2. HO2S sensor coated with contaminants.
3. Sensor circuit open or shorted to ground.

If necessary, see CIRCUIT TEST H in the appropriate TESTS W/CODES - EEC-IV article for additional specifications and circuit testing procedures.

INERTIA FUEL SHUTOFF (IFS) SWITCH

1. Turn ignition off. Locate IFS switch in rear of vehicle. Ensure IFS switch reset button is not in upper (tripped) position. Using a jumper lead, ground FP terminal at Data Link Connector (DLC). (Scheme 2)
2. Turn ignition on. Leaving inertia switch connector attached, check voltage at IFS switch connector. If 10.5 volts is not present, repair circuit. If 10.5 volts is present at one terminal only, replace IFS switch.
3. If 10.5 volts is present at both terminals, turn ignition off. Disconnect IFS switch connector. Ensure IFS switch reset button is in down position. Measure resistance between IFS switch terminals.
4. Resistance should be 5 ohms or less. If resistance is more than 5 ohms, replace switch. For additional circuit testing information, refer to CIRCUIT TEST J in the appropriate «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article.

INTAKE AIR TEMPERATURE (IAT) SENSOR

IAT sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, check resistance between sensor terminals. For specifications, see the SENSOR RANGE CHARTS article. For additional testing information, see CIRCUIT TEST DA in the TESTS W/CODES - EEC-IV article.

KNOCK SENSOR (KS)

KS is located on cylinder block. Sensor is tested by substitution or by manually generating a knock to ensure sensor will set a diagnostic trouble code. Faults in sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the appropriate TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST DG in the same article for additional sensor circuit testing procedures.

MASS AIRFLOW (MAF) SENSOR

1. Faults in MAF sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article. If diagnostic trouble code has not been set, install Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Start engine, and allow it to idle.
2. Measure voltage between test pin No. 50 and negative battery terminal. If voltage is not .36-1.50 volts, replace MAF sensor. If voltage is .36-1.50 volts, MAF sensor is okay. See CIRCUIT TEST DC in the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article for circuit testing.

POWER STEERING PRESSURE SWITCH (PSPS)

Faulty PSPS or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST FF in the same article for testing.

PRESSURE FEEDBACK (PFE) EGR SENSOR & DIFFERENTIAL PFE (DPFE)

SENSOR

Faults in sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST DL in the same article for testing.

THROTTLE POSITION (TP) SENSOR

Faults in TP sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see THROTTLE POSITION (TP) SENSOR in the ADJUSTMENTS article for adjusting procedures. For testing procedures, see CIRCUIT TEST DH in the TESTS W/CODES - EEC-IV article.

VEHICLE SPEED SENSOR (VSS)

1. Faults in VSS or circuit should set diagnostic trouble code. See QUICK TEST in the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article. Disconnect VSS electrical connector if diagnostic trouble code has not been set.
2. Using DVOM, measure resistance between sensor terminals. Replace sensor if resistance is not 190-250 ohms. If sensor is 190-250 ohms, see CIRCUIT TEST DP in the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article for additional circuit testing.

Constant Control Relay Module (CCRM)

Faults in CCRM or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST X in the same article for CCRM testing.

Variable Control Relay Module (VCRM)

Faults in VCRM or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST XB in the same article for testing.

Secondary Air Injection By-Pass/Diverter (AIRB/AIRD)

Solenoids

1. Faults in secondary air injection solenoids or circuits should set a diagnostic trouble code. See QUICK TEST in the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article. If diagnostic trouble code has not been set, disconnect solenoid to be tested.
2. Measure resistance between sensor terminals. If resistance is not 50-100 ohms, replace solenoid. If resistance is 50-100 ohms, solenoid is okay. See CIRCUIT TEST KC in «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article for additional circuit testing.

Canister Purge (CANP) Solenoid

1. Faults in CANP solenoid or circuit should set a diagnostic trouble code. See QUICK TEST in the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article. If diagnostic trouble code has not been set, disconnect CANP solenoid harness connector.
2. Measure resistance across CANP solenoid terminals. If resistance is not 30-90 ohms, replace CANP solenoid. If resistance is 30-90 ohms, disconnect vacuum hose at CANP solenoid on manifold vacuum side.
3. Apply 16 in. Hg vacuum to manifold vacuum side of solenoid. CANP solenoid should hold vacuum for 20 seconds. If CANP solenoid does not hold vacuum for 20 seconds, replace CANP solenoid. If CANP solenoid holds vacuum for 20 seconds, solenoid is okay. If additional testing is required, see CIRCUIT TEST KD in the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article for circuit testing.

EGR Solenoid

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

Idle Air Control Solenoid

Faults in idle air control solenoid or circuits should set a diagnostic trouble code. See QUICK TEST in the appropriate TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST KE in the same article for testing.

FUEL SYSTEMS

Note. In following test procedures, KOEO refers to Key On Engine Off and KOER refers to Key On Engine Running.

FUEL SYSTEM PRESSURE RELEASE

1. Remove fuel cap to release fuel tank pressure. Remove relief valve cap. Relief valve is located on fuel supply manifold. Using Fuel Pressure Gauge (T80L-9974-B), release fuel pressure from relief valve (Schrader valve).
2. If fuel pressure gauge is not available, disconnect electrical connector to IFS switch. For IFS switch location, see INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION table. Crank engine for 15 seconds to reduce system pressure.

INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION

FUEL DELIVERY

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

Fuel Pump Relay

See RELAYS under MODULES, RELAYS & SOLENOIDS.

See CIRCUIT TEST X in the TESTS W/CODES - EEC-IV article.

See CIRCUIT TEST XB in TESTS W/CODES - EEC-IV article.

Scheme 2

1. System Integrity Check Perform QUICK TEST to verify pass code. See the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article. Service any fuel related codes prior to continuing with this test. On all models, perform the following checks: Ensure Inertia Fuel Shutoff (IFS) switch reset button is not in upper (tripped) position. See INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION table. Ensure battery is fully charged and fuel-related fuses are okay. Check fuel tank contents and fuel gauge accuracy. If any fault is detected, repair as necessary. If system checks are okay, go to next step.
2. Check Fuel Pressure Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE. Install fuel pressure gauge. Connect a jumper wire between ground and fuel pump test terminal at Data Link Connector (DLC). (Scheme 2)Turn ignition on to activate pump. Check and record fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(/lincoln/mark-viii/i-1992-1998/remont/specifications/#fuel-pressure-specifications) article. Proceed to appropriate step: If fuel pressure is within specification, go to next step. If fuel pressure is low, go to step 11). If fuel pressure is high, go to step 12). (Scheme 2): Identifying Data Link Connector Terminals
3. Check For Fuel Pressure Leak-Down Operate fuel pump as in step 2) for a minimum of 30 seconds. Turn ignition off, and disconnect jumper wire from DLC. Wait one minute then check fuel pressure gauge. If fuel pressure remains within 5 psi of specification, go to step 5). If fuel pressure does not remain within 5 psi of specification, go to next step.
4. Check Fuel Pressure Regulator Diaphragm Turn ignition off. Ensure vacuum hose is connected to fuel pressure regulator. Start and run engine for 10 seconds. Stop engine, and wait 10 seconds. Start and run engine for 10 seconds. Stop engine. Remove vacuum hose from pressure regulator. If fuel is present in vacuum port, replace fuel pressure regulator, and repeat step 2). If fuel is not present, either fuel injectors are leaking down or check valve in fuel pump defective. Repair as necessary and repeat step 2).
5. Check Fuel Pressure With Engine Load Ensure vacuum hose is still disconnected from pressure regulator. Observe pressure gauge while driving vehicle with heavy accelerations. If fuel pressure remains within 3 psi during test, reconnect vacuum hose to pressure regulator and go to next step. If fuel pressure does not remain within 3 psi, go to step 8).
6. Check Fuel Pressure Regulator Install vacuum gauge to intake manifold. Start engine. Observe vacuum and fuel pressure gauge while accelerating and decelerating engine. When engine is accelerating, vacuum reading should decrease and fuel system pressure should increase. When engine is decelerating, vacuum reading should increase and fuel system pressure should decrease. If readings are as specified, fuel system is okay and test is compete. If gauge readings are not as specified, go to next step
7. Check Vacuum Supply Disconnect and plug fuel pressure regulator hose. Attach vacuum pump to fuel pressure regulator. Start engine. Apply vacuum to pressure regulator while observing fuel pressure gauge. If fuel pressure changes as vacuum changes, repair restriction in vacuum supply hose. If fuel pressure does not change as vacuum changes, replace fuel pressure regulator.
8. Check Fuel Filter Check for plugged fuel filter. Replace filter as necessary, and repeat step 2). If filter is okay, go to next step.
9. Check Voltage At Both Pump Speeds Turn ignition off. Connect DVOM between ground and either terminal at Inertia Fuel Shutoff (IFS) switch. IFS switch is located in left side of trunk. Start engine. Voltage reading should be about 9 volts at idle and 13 volts at 3500 RPM. If voltage is not as specified, go to next step. If voltage is as specified, check for faulty fuel pump ground connection. Repair as necessary. If ground is okay, replace fuel pump.
10. Check Variable Control Relay Module (VCRM) See CIRCUIT TEST XB in the «TESTS W/CODES - EEC-IV»(/lincoln/mark-viii/i-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec-iv) article.
11. Check For Low Pressure Causes Turn ignition off. Release fuel system pressure. See FUEL SYSTEM PRESSURE RELEASE. Disconnect fuel return hose from pressure regulator. Using a separate piece of fuel hose, connect one end of hose to fuel return port at pressure regulator and place other end of hose into a suitable container. With jumper wire still connected to DLC as in step 2), turn ignition on (engine off). If fuel pressure is still low and fuel is being returned to container, replace pressure regulator. If fuel pressure is still low and fuel is not being returned to container, replace fuel pump and repeat step 2).
12. Check For High Pressure Causes Turn ignition off. Release fuel system pressure. See FUEL SYSTEM PRESSURE RELEASE. Disconnect fuel return hose from pressure regulator. Using a separate piece of fuel hose, connect one end of hose to fuel return port at pressure regulator and place other end of hose into a suitable container. With jumper wire still connected to DLC as in step 2), turn ignition on (engine off). If fuel pressure is within specification, replace pressure regulator and repeat step 2). For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(/lincoln/mark-viii/i-1992-1998/remont/specifications/#fuel-pressure-specifications) article. If fuel pressure is not within specification, go to next step.
13. Check Fuel Return System Turn ignition off. Fuel return hose should still be disconnected at pressure regulator. Disconnect fuel return hose near fuel tank. Apply 3-5 psi of regulated air to return line port at pressure regulator. If air flows freely through return line, replace fuel pump and repeat step 2). If air does not flow freely, check fuel return system for restrictions. Repair as necessary, repeat step 2).

Fuel Injector Check

1. Connect tachometer to engine. Run engine at idle. Observe tachometer, and disconnect and reconnect injectors individually. When disconnected, each injector should cause a momentary drop in engine speed of at least 100 RPM. Engine RPM drop should only be momentary, as PCM will attempt to re-establish correct idle RPM.
2. Replace any injectors which do not cause sufficient drop in engine speed. When test is complete, check idle speed. Refer to emission control specifications on decal in engine compartment, or see IDLE SPEED in «ADJUSTMENTS»(ref-23158) article.

Fuel Injector Circuit

Disconnect injector harness connectors. Using digital ohmmeter, measure resistance between each injector terminal. Individual injector resistance should be 13-19 ohms on all models.

IDLE CONTROL SYSTEM

Faults in idle control system or circuit should set a diagnostic trouble code. See QUICK TEST in the appropriate TESTS W/CODES - EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST KE in the same article for testing.

IGNITION SYSTEM

Note. For additional information and descriptions, see IGNITION SYSTEM in the THEORY/OPERATION article.

IGNITION SYSTEM ACRONYMS

IGNITION SYSTEM IDENTIFICATION

EI SYSTEM (HIGH DATA RATE)

Note. Start all diagnostics with QUICK TEST. See TESTS W/CODES - EEC-IV article. Following tests are dependent on results and service codes received during QUICK TEST.

Note. Use EI Diagnostic Cable (Rotunda 007-00059) to diagnose system. 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, become familiar with system wiring diagram and system operation.

Note. (Scheme 3)-7 when using pinpoint test procedures.

Preliminary Check

Visually inspect engine compartment to ensure all vacuum hoses and spark plug wires are properly connected. Examine all wiring harnesses and connectors for damaged insulation, burned, overheated or damaged pins, and loose or broken conditions. Check sensor shield connector. Ensure Ignition Control Module (ICM) mounting screws are tight and battery is fully charged. All accessories should be off during diagnosis.

Test Equipment

Following equipment should be used in these test procedures.

1. EI 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 (T83L-50-EEC-IV)
6. Spark Tester (D81P-6666-A)
7. Inductive Timing Light
8. Test Light (LED Type) Or Logic Probe (LED Type)

Diagnostic Aids

Circuits are identified in all capital letters (acronyms). For example, Profile Ignition Pickup is identified as PIP.

Manufacturer's breakout box overlay test terminals are identified by a "J" prefix. For example, J31 (PIP). The J31 indicates that the measurement is to be taken at terminal No. 31 at the breakout box. The (PIP) indicates that the Profile Ignition Pickup circuit is being checked.

When the letter "I" follows the circuit identification, it implies that the measurement is being taken at the ICM. For example, J31 (PIP I). The (PIP I) implies that the measurement is of the PIP circuit at the ICM.

When the letter "S" follows the circuit identification, it implies that the measurement is being taken at the CKP sensor. For example, J32 (CKP+ S). The (CKP+ S) implies that the measurement is of the CKP sensor positive circuit at the CKP sensor.

When the letter "C" follows the circuit identification, it implies that the measurement is being taken at the coil. For example, J10 (LC3C). The (LC3C) implies that the measurement is of the C3 circuit at the left coil pack.

The following information should also be noted during testing

1. When checking a wiring harness, perform both a visual inspection and a continuity test. Inspect terminal connector pins for damage, bending, spreading and corrosion when directed to remove a connector.
2. Spark timing adjustments are not possible. Timing is controlled by ICM with input from PCM.
3. When checking voltage drop to ground, circuit must have a voltage drop of less than one volt.
4. Battery voltage (VBAT) is any voltage reading within 2 volts of actual battery voltage.
5. EEC-IV Breakout Box (T83L-50-EEC-IV) connected to EI diagnostic cable is referred to as breakout box or EI breakout box. If a second breakout box is connected to PCM wiring harness connector, it will be referred to as second or PCM breakout box. This setup allows testing of EI components and wiring harness circuits.

Note. A 12-volt incandescent (high voltage) test light should not be used to test circuit signals. It will load circuit and may cause incorrect measurements or faulty EI/PCM operation (engine stall).

EI PINPOINT TEST INDEX

Note. Steps in pinpoint tests are designed to correct one ignition failure at a time. When a component is replaced or service is completed, remove all test equipment. Reconnect all components, and perform QUICK TEST. See TESTS W/CODES - EEC-IV article.

EI Diagnostic Cable Diagram. Scheme 3

EI Wiring Diagram. Scheme 4

EI System Pin Voltage Chart. Scheme 5

EI Signal Diagram. Scheme 6

EI Block Diagram. Scheme 7

PINPOINT TEST A - NO START

PINPOINT TEST B - CODE 212 OR 226: IDM FAILURE

PINPOINT TEST C - CODE 213 OR LACK OF POWER OR POOR FUEL

ECONOMY

PINPOINT TEST D - CODE 215, 216, 217 OR 238 COIL FAILURE

Air Pump

Check belt tension and adjust if necessary. Disconnect air supply hose from secondary Air Injection By-Pass (AIRB) valve. Start engine. If airflow is felt at pump outlet and increases as engine speed is increased, pump is okay. If airflow is not felt at pump outlet and/or does not increase as engine speed is increased, replace air 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 it for plugging. If no plugging or leaks are found, silencer is okay. If any plugging or leaks are found, repair or replace as necessary.

Secondary Air Injection By-Pass (AIRB) Valve

(Normally Closed)

Scheme 8

1. Disconnect air supply hose at AIRB valve outlet. (Scheme 8) Remove vacuum line from vacuum nipple. Ensure vacuum exists at vacuum line before proceeding. (Scheme 8): Normally Closed Secondary Air Injection By-Pass (AIRB) Valve
2. Reconnect vacuum line to vacuum nipple. With engine speed at 1500 RPM, air pump supply air should be heard and felt at AIRB valve outlet.
3. With engine speed 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 silencer ports or at dump port.
4. If the normally closed AIRB valve does not perform as described in steps 2) and 3), check air pump for faults. If air pump is operating satisfactorily, replace AIRB valve.

Air Check Valve

1. Visually inspect secondary air hoses, tubes, control valves and check valves for leaks which may be due to backflow of exhaust gases. If holes are found and/or traces of exhaust gas products are present, replace check valve.
2. Check valve should allow free flow of air in direction of arrow only. (Scheme 9) Valves should check or block free flow of exhaust gas air in opposite direction.
3. If air does not flow as indicated or if exhaust gas backflows opposite arrow direction in illustration, replace check valve.

Testing Air Check Valve. Scheme 9

Air Injection Diverter (AIRD) Valve

1. Disconnect air supply hose at inlet. Accelerate engine speed 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 10) Remove vacuum line at vacuum nipple. Accelerate engine speed to 1500 RPM. Airflow should be heard and felt at outlet "B" with little or no airflow at outlet "A".
3. Attach a hose from manifold vacuum fitting to air supply control valve vacuum nipple. Accelerate engine speed 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 air flows as described in steps 1)-3), valve is okay. Reinstall hoses and clamps.

Air Injection Diverter (AIRD) Valve. Scheme 10

Air Pump Resonator

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

Scheme 11

1. Disconnect hoses from outlets "A" and "B". (Scheme 11) Disconnect and plug vacuum line to port "D". With engine operating at 1500 RPM, airflow should come out of by-pass vents. (Scheme 11): Identifying Combination AIRB/AIRD Valve
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 speed to 1500 RPM. Airflow should come out of outlet "B". Airflow should not be detected at outlet "A".
3. Apply 8-10 in. Hg vacuum to port "S". With engine operating at 1500 RPM, airflow should come out of outlet "A". If valve is bleed type, less air will flow from outlet "A" or "B" and main discharge will change when vacuum is applied to port "S".
4. If conditions in previous steps are not met, replace valve. If above conditions are met, valve is okay. Reconnect hoses and vacuum lines.

Vacuum Check Valve

Apply 16 in. Hg vacuum to check valve. If vacuum remains greater than 15 in. Hg for 10 seconds, valve operation is normal. If vacuum drops in less than 10 seconds, 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. Suction should be felt at valve inlet. If suction is not felt, replace valve.

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

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure less than one in. Hg vacuum to EGR valve exists at idle with engine at normal operating temperature. NOTE: EVR solenoid has a continuous internal leak which produces a vacuum signal of less than one in. Hg vacuum at idle.
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 it in Neutral. Note idle speed. Using vacuum pump, apply 5-10 in. Hg vacuum to EGR valve. When vacuum is fully applied to EGR valve, one or more of following should occur: 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 engine does not respond as specified. 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 in the TESTS W/CODES - EEC-IV article. If no service code has been set, see CIRCUIT TEST DN in the same article for diagnostic procedures.

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)

EGR Transducer

Faults in DPFE transducer or circuit should set a service code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If service code has not been set, see CIRCUIT TEST DL in the same article for diagnostic procedures.

Pressure Feedback Electronic (PFE) EGR Transducer

Faults in PFE EGR transducer or circuit should set a service code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If no service code has been set, see CIRCUIT TEST DL in the same article for diagnostic procedures.

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

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

Canister Purge Regulator (CPR) Valve

With CPR valve de-energized, apply 17 in. Hg vacuum to source port. Valve should not pass air. Apply 9-14 volts to one electrical terminal, and ground other. Valve should open and pass air. If valve does not operate as described, replace valve.

Faults in CANP solenoid or circuit should set a service code. See QUICK TEST in the TESTS W/CODES - EEC-IV article. If service code has not been set, see CIRCUIT TEST KD in the same article for diagnostic procedures.

EVAP Canister

Canister does not have any moving parts. Check for loose, missing, cracked or broken connections and parts. Repair or replace as necessary. Canister should not contain any liquid.

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 it to normal operating temperature. 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.

See also:
• BASIC TESTING - 4.6L
• TESTS W/CODES - EEC-IV
• WIRING DIAGRAMS
• FUEL PRESSURE SPECIFICATIONS
• TESTS W/O CODES