Engine Controls - System & Component Testing - 5.8L Eec-Iv: Other Ford Pickup F350

Ground Circuits

1. Using a DVOM, check for continuity to ground on PCM terminals No. 20, 40 and 60. (Scheme 396) Resistance should be zero ohms. If resistance is not zero ohms, repair open to ground.
2. Touch negative lead of voltmeter to a good ground. With vehicle running, backprobe positive lead of voltmeter to each ground terminal. Voltmeter should indicate less than one volt. If 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 PCM terminal No. 1 (KAPWR) and ground. Also 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 TESTS W/CODES - 5.8L EEC-IV article.

PCM LOCATION

Identifying PCM 60-Pin Connector Terminals. Scheme 396

ENGINE SENSORS & SWITCHES

Note. For additional sensor testing specifications, see SENSOR RANGE CHARTS - 5.8L article.

Clutch Pedal Position (CPP) Switch

Faults in CPP switch or switch circuits should set diagnostic trouble code. See QUICK TEST in TESTS W/CODES - 5.8L EEC-IV article. If no diagnostic trouble code has been set, see CIRCUIT TEST TA for additional switch testing and specifications.

Engine Coolant Temperature (ECT) Sensor

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 - 5.8L article. For additional testing information and circuit testing of sensor, see CIRCUIT TEST DA in the TESTS W/CODES - 5.8L EEC-IV article.

EGR Valve Position (EVP) Sensor/EGR Vacuum Regulator (EVR)

Solenoid

Faults in sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - 5.8L EEC-IV article. If no diagnostic trouble code has been set, see CIRCUIT TEST DN in the TESTS W/CODES - 5.8L EEC-IV article for sensor specifications and circuit testing procedure.

Heated Oxygen Sensor (HO2S)

Faults in sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - 5.8L EEC-IV article. If no diagnostic trouble code has been set, see CIRCUIT TEST H in the TESTS W/CODES - 5.8L EEC-IV article for additional sensor specifications and circuit testing procedures. Ensure that none of following conditions exist

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

Inertia Fuel Shutoff (IFS) Switch

1. Ensure ignition is off. IFS switch is located behind right kick panel. Push down on reset button to ensure switch is closed. Measure resistance between switch terminals.
2. If resistance is 5 ohms or less, switch is okay. For additional circuit testing information, refer to CIRCUIT TEST J in the «TESTS W/CODES - 5.8L EEC-IV»(ref-23598) article. If resistance is more 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 IFS switch operation.

Intake Air Temperature (IAT) Sensor

1. Sensor requires a 5-volt reference signal during engine operation. With sensor disconnected, sensor may be checked by measuring resistance between sensor terminals.
2. For specifications, see the «SENSOR RANGE CHARTS - 5.8L»(ref-23784) article. For additional testing information and circuit testing of sensor, see CIRCUIT TEST DA in the «TESTS W/CODES - 5.8L EEC-IV»(ref-23598) article.

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 and apply 18 in. Hg vacuum to sensor. Sensor should hold vacuum. If sensor does not hold vacuum, replace sensor. Faults in MAP sensor or circuit should set a diagnostic trouble code. See QUICK TEST in the TESTS W/CODES - 5.8L EEC-IV article. If no diagnostic trouble code has been set, see CIRCUIT TEST DF in the TESTS W/CODES - 5.8L EEC-IV article for additional sensor testing and specifications.

Park/Neutral Position (PNP) Switch

Faults in PNP switch or switch circuits should set diagnostic trouble code. See QUICK TEST in TESTS W/CODES - 5.8L EEC-IV article. If no diagnostic trouble code has been set, see CIRCUIT TEST TA in the TESTS W/CODES - 5.8L EEC-IV article for additional switch testing and specifications.

Throttle Position (TP) Sensor

Faults in TP sensor or circuit should set a diagnostic trouble code. See QUICK TEST in TESTS W/CODES - 5.8L EEC-IV article. If no diagnostic trouble code has been set, see CIRCUIT TEST DH in the TESTS W/CODES - 5.8L EEC-IV article for additional sensor testing and specifications. Ensure none of following conditions exist

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

RELAYS

Note. For more fuel delivery system testing, see CIRCUIT TEST J in TESTS W/CODES - 5.8L EEC-IV article.

Fuel Pump Relay

To check fuel pump relay, see CIRCUIT TEST J, STEP 2) in TESTS W/CODES - 5.8L EEC-IV article.

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

Solenoids

Disconnect solenoid harness connector, and measure resistance across terminals. Resistance should be 50-100 ohms. If resistance is not as specified, replace solenoid. Faults in solenoid or circuit should set a diagnostic trouble code. See QUICK TEST procedures in the TESTS W/CODES - 5.8L EEC-IV article. If no diagnostic trouble code has been set, see CIRCUIT TEST KC in TESTS W/CODES - 5.8L EEC-IV article for additional solenoid and 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 - 5.8L EEC-IV»(ref-23598) 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 procedures under CIRCUIT TEST KD in the «TESTS W/CODES - 5.8L EEC-IV»(ref-23598) article for circuit testing.

EGR Solenoid

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

Idle Air Control (IAC) Solenoid

1. Solenoid is by-pass air type. Ensure ignition is off. Disconnect IAC solenoid harness connector. Set DVOM to 200-ohm scale. Measure resistance between IAC solenoid connector terminals. Solenoid has diode. (Scheme 397) Connect DVOM (+) test lead to terminal VPWR (Red wire) and DVOM (-) lead to terminal IAC (White/Light Blue wire).
2. Resistance should be 6-13 ohms. If not 6-13 ohms, replace solenoid. Faults in IAC solenoid or circuit should set diagnostic trouble code. See QUICK TEST in «TESTS W/CODES - 5.8L EEC-IV»(ref-23598) article. If no diagnostic trouble code has been set, see CIRCUIT TEST KE in the «TESTS W/CODES - 5.8L EEC-IV»(ref-23598) article for additional testing and specifications.

Identifying IAC Solenoid Connector Terminals. Scheme 397

FUEL SYSTEM

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

With Fuel Pressure Gauge

Remove fuel tank cap to release fuel tank pressure. Connect Fuel Pressure Gauge (T80L-9974-B), to pressure relief valve (Schrader valve), located on fuel injection manifold rail. Using a suitable container, release fuel pressure.

Without Fuel Pressure Gauge

If fuel pressure gauge is not available, disconnect Inertia Fuel Shutoff (IFS) switch. IFS switch is located behind right kick panel. Remove fuel cap to release fuel tank pressure. Crank engine for 15 seconds to release system pressure.

See RELAYS under RELAYS & SOLENOIDS.

Note. For 1995 fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. For 1996 fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

Scheme 398

1. System Integrity Check Perform the following checks: Visually inspect fuel system (fuel lines, filter, pump, injectors, pressure regulator, etc.). Ensure Inertia Fuel Shutoff (IFS) switch reset button is not in upper (tripped) position. On all models, IFS switch is located behind right kick panel. Ensure battery is fully charged and fuel-related fuses are okay. Check fuel tank contents and fuel gauge accuracy. On vehicles with 2 fuel tanks, check both tanks. 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»(ref-23711-S10593644992001010300000). Install fuel pressure gauge. Connect a jumper wire between ground and fuel pump test terminal at Data Link Connector (DLC). (Scheme 398) Turn ignition on to activate pump. Check and record fuel pressure. For 1995 fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123321) article. For 1996 fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123322) article. Proceed to appropriate step. If fuel pressure is within specification, go to next step. If fuel pressure is low, go to step 10). If fuel pressure is high, go to step 11). (Scheme 398): 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 (34 kPa) of specification, go to step 5). If fuel pressure does not remain within 5 psi (34 kPa) 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 is 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 vehicle is equipped with 2 fuel tanks, perform test on both tanks. If fuel pressure remains within 3 psi (21 kPa) during test, reconnect vacuum hose to pressure regulator and go to next step. If fuel pressure does not remain within 3 psi (21 kPa), 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. Pressurize fuel system as in step 2), and check fuel pressure.For 1995 fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123321) article. For 1996 fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123322) article. If fuel pressure is as specified, repeat step 3). If fuel pressure is not as specified, go to next step.
9. Check Fuel Pump Voltage Turn ignition on. Disconnect harness connector from pump/sender unit. Ground terminal FP at Data Link Connector (DLC). With DVOM on 20-volt scale, measure voltage to fuel pump. If battery voltage is not present, locate and repair cause of low voltage and repeat step 2). If battery voltage is present, check fuel pump ground connection. Repair as necessary. If ground is okay, replace fuel pump.
10. Check For Low Pressure Causes Turn ignition off. Release fuel system pressure. See procedures under «FUEL SYSTEM PRESSURE RELEASE»(ref-23711-S10593644992001010300000). 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 and repeat step 2). If fuel pressure is still low and fuel is not being returned to container, replace fuel pump and repeat step 2).
11. Check For High Pressure Causes Turn ignition off. Release fuel system pressure. See procedures under «FUEL SYSTEM PRESSURE RELEASE»(ref-23711-S10593644992001010300000). 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 not within specification, replace pressure regulator and repeat step 2). For 1995 fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123321) article. For 1996 fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123322) article. If fuel pressure is within specification, go to next step (models with 2 fuel tanks) or step 13) (models with one fuel tank).
12. Check Fuel Return System (Models With 2 Tanks) Turn ignition off. Check fuel return lines for blockage, kinking and pinching. If only one tank is affected, pay close attention to return line between "Y" in return line and affected tank. If both tanks are affected, check return line between pressure regulator and "Y" in fuel return line. Repair as necessary. If fuel return lines are okay, ensure fuel return hose is still disconnected at pressure regulator. Disconnect fuel return hose near fuel tank. Apply 3-5 psi (21-34 kPa) of regulated air to return line port at pressure regulator. If air flows freely through return line, replace fuel pump assembly and repeat step 2). If air does not flow freely, check fuel return system for restrictions. Repair as necessary and repeat step 2).
13. Check Fuel Return System (Models With One Tank) Turn ignition off. Fuel return hose should still be disconnected at pressure regulator. Disconnect fuel return hose near fuel tank. Apply 3-5 psi (21-34 kPa) 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 and repeat step 2).

FUEL PRESSURE REGULATOR

1. Ensure ignition is off. Connect fuel pressure gauge to Schrader valve on fuel rail. Ensure manifold vacuum supply tube is connected to fuel pressure regulator. Start engine and run for 10 seconds. Stop engine and wait 10 seconds. Start engine and operate for 10 seconds. Stop engine. Remove pressure regulator vacuum hose. Check vacuum port for fuel.
2. If fuel is present, replace fuel pressure regulator and repeat test. If fuel is not present, start engine and run for 30 seconds. Stop engine. Check fuel pressure gauge. If pressure does not drop, go to step 4). If pressure drops more than 5 psi (34 kPa) in 60 seconds, disconnect and plug fuel return line at engine. Cycle ignition on and off until normal fuel pressure is obtained.
3. Turn ignition off. Check fuel pressure gauge. If pressure drops more than 5 psi (34 kPa) in 30 seconds, replace fuel pump assembly. If pressure does not drop more than 5 psi (34 kPa) in 30 seconds, replace fuel pressure regulator.
4. Ensure ignition 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 vacuum. (Scheme 399) 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.

Identifying Fuel Pressure Regulator Components. Scheme 399

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 IAC 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.

Fuel Injector Circuit

Disconnect injector harness connectors. Using digital ohmmeter, measure resistance between each injector terminal. Individual injector resistance should be 11-18 ohms on all models.

IDLE CONTROL SYSTEM

Faults in idle control system/circuit should set diagnostic trouble code. See QUICK TEST in TESTS W/CODES - 5.8L EEC-IV article. If diagnostic trouble code has not been set, see CIRCUIT TEST KE for testing.

IGNITION SYSTEM

Note. For additional information and descriptions, see IGNITION SYSTEMS in THEORY/OPERATION - 5.8L EEC-IV article.

IGNITION SYSTEM ACRONYMS

Preliminary Check

Perform following preliminary checks

1. Visually inspect engine compartment to verify vacuum hoses and spark plug wires are properly routed and securely connected.
2. Examine all wiring harnesses and connectors for damage.
3. Ensure ICM is securely fastened to inner fenderwell.
4. Ensure battery is fully charged.
5. All accessories should be off during diagnosis.

Equipment Hookup

1. Position proper Distributor Ignition (DI) overlay onto tester.
2. Select and install proper program cartridge into tester cartridge slot.
3. Select and connect proper DI harness adapter onto tester.
4. Ensure WIGGLE SWITCH test switch is off.
5. Disconnect Ignition Control Module (ICM) connector and plug connector into male connector of tester. Plug female connector of tester into ICM. Perform Tester Self-Test Turn ignition on. Press tester RESET button. Tester will perform a self-test every time tester is reset or powered-up. All LEDs should light and a beep should be heard. If tester fails to perform self-test and ICM PWR LED is off, go to next step. If tester passes self-test, go to step 3). Self-Test Failure Turn ignition off. Disconnect tester from vehicle. Connect a jumper wire between ICM PWR port of tester and positive battery terminal. Connect another jumper wire between IGN GND port of tester and negative battery terminal. If tester performs self-test, reconnect tester to vehicle and go to PINPOINT TEST N. If any LEDs DO NOT light or tester does not beep, tester is defective. Attempt To Recreate Fault Turn ignition on. If any LEDs turn on, perform appropriate PINPOINT TEST. See DIAGNOSTICS BY CODE OR SYMPTOM table. If no LEDs turn on, crank engine for 5-10 seconds or start engine and attempt to recreate driveability fault. If any LEDs are now on, perform appropriate PINPOINT TEST. If LEDs still do not turn on, problem cannot be duplicated at this time. Perform CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST in «TESTS W/CODES - 5.8L EEC-IV»(ref-23598) article.

DIAGNOSTICS BY CODE OR SYMPTOM

SECONDARY AIR INJECTION

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 pump does not operate as specified, check for plugged air silencer/filter (if equipped) inlet. Clean as necessary and recheck pump operation. If vehicle is not equipped with an air silencer/filter, replace pump.

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

Air silencer is mounted in engine compartment and is connected to air pump by a flexible hose. 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.

Identifying EI Secondary Voltage Scope Patterns. Scheme 400

1. Disconnect air supply hose at valve outlet. see scheme 8 Remove vacuum line from vacuum nipple, and check for presence of vacuum at nipple. Ensure vacuum exists at nipple before proceeding. see scheme 8: Testing Normally Closed Air By-Pass (AIRB) Valve
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 silencer ports or at dump port.
4. If normally closed air by-pass valve does not perform as described in steps 2) and 3), check air pump for faults. If air pump is operating satisfactorily, replace air by-pass valve.

Air Check Valve

1. Visually inspect 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 401) Valve(s) should check (or block) free flow of exhaust gas air in opposite direction. If air does not flow as indicated or if exhaust gas backflows opposite of direction of arrow in illustration, replace check valve.

Testing Air Check Valve. Scheme 401

Air Injection Diverter (AIRD) Valve (Without Vent)

1. With engine cold, vacuum signal should be present at valve. 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 402) 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 exist at outlet "A" with little or no airflow at outlet "B".
4. If valve does not operate as specified in steps 1), 2) and 3), replace valve. If airflow operates as specified, valve is okay. Reinstall hoses and clamps.

Testing Air Injection Diverter (AIRD) Valve (Non-Vented). Scheme 402

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 AIRB/AIRD Valve

1. Disconnect hoses from outlets "A" and "B". (Scheme 403) Disconnect and plug vacuum line to port "D". With engine operating at 1500 RPM, airflow should be flowing from 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 main discharge will change when vacuum is applied to port "S".
4. If conditions in previous steps are not met, replace valve. If conditions are met, valve is okay. Reconnect hoses and vacuum lines.

Testing Combination AIRB/AIRD Valve. Scheme 403

Dual Air Control Solenoid Valves

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

Air Injection Solenoid Valve

1. Vacuum control valve is normally closed when not energized. Valve may come with or without controlled bleed. Unstable idle may result from a leaking AIR solenoid valve. An electrical malfunction with valve should set a Diagnostic Trouble Code (DTC).
2. If unstable idle exists, remove vacuum hose from valve and plug hose. Warm engine to normal operating temperature. If idle becomes smoother, replace valve.

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 is okay. If vacuum drops faster, replace valve.

Vacuum Reservoir

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

EXHAUST GAS RECIRCULATION (EGR)

Note. EVR solenoid has a constant internal leak. A small vacuum signal of less than one in. Hg vacuum is noticeable at idle.

EGR Valve Position (EVP) Sensor

Faults in EVP sensor or circuit should set a Diagnostic Trouble Code (DTC). See QUICK TEST in TESTS W/CODES - 5.8L EEC-IV article. If no DTC has been set, see CIRCUIT TEST DN.

EGR Valve

1. Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is less than one 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. 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, 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 system if engine does not stall or idle speed 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) Solenoid

Faults in EVR or circuit should set a trouble code. See QUICK TEST in the TESTS W/CODES - 5.8L EEC-IV article. If no trouble code has been set, see CIRCUIT TEST DN 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 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 .5 in. Hg in 60 seconds. If vacuum loss is greater than specified, replace reservoir.

1. Disconnect CANP solenoid harness connector. Set DVOM to 200-ohm scale. Measure resistance across CANP solenoid terminals. Resistance should be 30-90 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 trouble code. See QUICK TEST in «TESTS W/CODES - 5.8L EEC-IV»(ref-23598) article. If no trouble code has been set, see CIRCUIT TEST KD for additional solenoid and circuit testing.

EVAP Canister

There are no moving parts in canister. Check for loose, missing, cracked or broken connections and 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. If valve does not rattle when shaken, replace valve. Start engine and warm to normal operating temperature.
2. 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.