Engine Controls - Removal, Installation & Overhaul - 4.3l Chevrolet Chevy Van G2500

INTRODUCTION

This article contains removal, overhaul and installation procedures (when information was available at time of publication). If component removal and installation is primarily an unbolt and bolt-on procedure, only a torque specification may be furnished.

POWERTRAIN CONTROL MODULE (PCM)

Note. Before replacing PCM, carefully inspect all wiring and control components. Failure to test for short circuits may result in repeated PCM failure due to shorts and Quad-Driver failure. To prevent internal damage to PCM, ensure ignition switch is in OFF position when connecting or disconnecting PCM connectors or any electrical components.

Note. When replacing defective PCM, remove knock sensor module from defective PCM. New PCM does not come equipped with knock sensor module. Install knock sensor module into new PCM.

Ensure ignition switch is in OFF position. Disconnect negative battery cable. Unplug electrical connectors from PCM. Remove PCM from vehicle. Remove access cover and remove knock sensor module from PCM.

Install knock sensor module in NEW PCM. Install access cover. Install PCM into vehicle. Connect electrical connectors to PCM. Reconnect negative battery cable.

ELECTRICALLY ERASABLE PROGRAMMABLE READ-ONLY MEMORY (EEPROM)

EEPROM is a permanent memory that is part of PCM. EEPROM cannot be replaced. EEPROM contains program and calibration information that PCM uses to control powertrain. If PCM is replaced, ensure that NEW PCM software/calibration is correct and most recent version for vehicle. EEPROM must be programmed when new PCM is installed. Program EEPROM using latest software for that specific vehicle.

Removal & Installation

1. KS module is located in PCM. Disconnect negative battery cable. Remove PCM from vehicle. See «POWERTRAIN CONTROL MODULE (PCM)»(/chevrolet/chevy-van-g2500/1996-1998/remont/removal-installation/#engine-controls-removal-installation-overhaul-43l__powertrain-control-module-pcm) . Position PCM with access cover up. Remove access cover from PCM.
2. Using thumb and forefinger, squeeze both ends of knock sensor module inward and pull module up from access hole. To install, reverse removal procedure. Ensure module latches into holder in PCM.

Note. If PCM is replaced, KS module must be transferred from original to replacement PCM.

CAMSHAFT POSITION (CMP) SENSOR

CMP sensor is located in the engine block adjacent to cam. (Scheme 1)

Scheme 1

CRANKSHAFT POSITION (CKP) SENSOR

CKP sensor is a magnetic sensor which protrudes into the block within about.050" (1.27 mm) from the crankshaft reluctor. (Scheme 2)

Scheme 2

1. Turn OFF the ignition switch.
2. Remove spark plug wires from the distributor cap.
3. Remove electrical connector from the base of the distributor.
4. Remove 2 screws that hold the distributor cap to the housing.
5. Discard screws.
6. Remove distributor cap from housing.
7. Use a grease pencil in order to note the position of the rotor in relation to the distributor housing. The mark is identified in the illustration as the number "1".
8. Mark distributor housing and intake manifold with a grease pencil.
9. Remove mounting clamp hold down bolt.
10. Remove distributor.
11. As the distributor is being removed from the engine, watch the rotor move in a counterclockwise direction about 42 degrees. This will appear as slightly more than one o'clock position.
12. Note the position of the rotor segment. Place a second mark on the base of the distributor. This will aid in achieving proper rotor alignment during the distributor installation. The second mark on the distributor housing is identified in the graphic as number 2.

Scheme 3

KNOCK SENSOR (KS)

Note. Cooling system may need draining prior to removing knock sensor.

Knock sensor is located on side of engine block. see scheme 5 Disconnect negative battery cable. Disconnect wiring harness connector from knock sensor. Remove knock sensor. To install, reverse removal procedure. Install sealant to sensor threads prior to installation. Tighten knock sensor to 14 ft. lbs. (19 N.m).

Scheme 4

FUEL SYSTEM PRESSURE RELIEF

1. Disconnect negative battery cable. Loosen fuel filler cap to relieve fuel tank pressure. Install Fuel Pressure Gauge (J-34730-1) to fuel pressure connection.
2. Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. Place gauge bleed hose into suitable container. Open bleed valve to bleed fuel pressure.

IN-LINE FUEL FILTER REPLACEMENT (NON-CARTRIDGE TYPE FILTER)

1. Disconnect the negative battery cable.
2. Relieve the fuel system pressure. Refer to «FUEL SYSTEM PRESSURE RELIEF»(/chevrolet/chevy-van-g2500/1996-1998/remont/removal-installation/#engine-controls-removal-installation-overhaul-43l__fuel-system-pressure-relief) .
3. Disconnect the fuel feed pipes at the filter.
4. Remove the in-line fuel filter clamp attaching hardware.
5. Remove the clamp from the filter.

1. Remove the protective caps from the new filter.
2. Install the clamp to the filter.
3. Install the in-line filter clamp attaching hardware. Install in the same positions as on the old filter noting direction of fuel flow arrow.
4. Connect the fuel feed pipes to the filter and tighten.
5. Connect the negative battery cable.
6. Turn ON the ignition switch for 2 seconds. Turn OFF the ignition switch for 10 seconds. Again, turn the ignition switch to the ON position. Check for fuel leaks.

FUEL PUMP

Note. When installing sending unit, DO NOT fold or twist strainer. This will restrict fuel flow.

1. Relieve fuel system pressure. See «FUEL SYSTEM PRESSURE RELIEF»(/chevrolet/chevy-van-g2500/1996-1998/remont/removal-installation/#engine-controls-removal-installation-overhaul-43l__fuel-system-pressure-relief) under FUEL SYSTEM. Disconnect negative battery cable. Raise vehicle and remove fuel tank. Using Sending Unit Remover (J-36608 or J-24187), remove sending unit and pump by turning cam lock counterclockwise.
2. Remove fuel pump from sending unit by pulling pump up into attaching hose while pulling outward from the bottom support. DO NOT damage rubber insulator or strainer. To install, reverse removal procedure.

Disconnect IAC valve harness connector. Remove IAC valve retaining screws and remove IAC valve from upper intake manifold assembly.

1. Inspect "O" ring for damage. Replace if necessary. If reusing IAC valve, DO NOT push or pull on pintle. Threads on worm gear will be damaged.
2. If replacing IAC valve, measure distance between tip of new IAC valve pintle and mounting flange. Distance should not exceed 1 1/8" (28 mm). If distance is more than specified, use finger pressure to slowly retract pintle. Lubricate "O" ring with clean engine oil.
3. Apply thread locking compound (Loctite 262) to IAC valve retaining screw threads. Install IAC valve to throttle body. Tighten IAC valve retaining screws to 27 INCH lbs. (3 N.m). Connect IAC valve harness connector.
4. To reset IAC valve pintle position, turn ignition on for 5 seconds. Turn ignition off for 10 seconds. Start engine and check for proper idle operation. Repeat IAC valve resetting procedure if proper idle operation cannot be obtained.
5. Connect IAC valve harness connector and install air cleaner. Start engine and allow it to reach normal operating temperature. Drive vehicle. It may be necessary to reset idle speed. To reset, disconnect negative battery cable for 10 seconds and reconnect. Cycle ignition on with engine off for 5 seconds. Turn ignition off for 10 seconds and restart vehicle. Proper idle will be initialized.

1. Disconnect negative battery cable. Remove air inlet duct fastener and duct. Disconnect IAC valve and TP sensor electrical connectors. Disconnect throttle and cruise control cables.
2. Remove accelerator cable bracket bolts and bracket. Remove wiring harness fastener nut and throttle body retaining studs. Remove throttle body assembly. Remove flange gasket and discard.
3. Clean gasket surface on intake manifold and throttle body. Install NEW flange gasket. Install throttle body. Install throttle body studs and wiring harness. Tighten throttle body studs to 18 ft. lbs. (24 N.m). To complete installation, reverse removal procedure. Ensure throttle and cruise control linkage does not hold throttle open.

UPPER INTAKE MANIFOLD ASSEMBLY (CSI)

Note. For more information, see UPPER INTAKE MANIFOLD under REMOVAL & INSTALLATION in 4.3L V6 - TRUCKS article.

1. Disconnect negative battery cable. Remove air inlet fastener and duct. Disconnect injector electrical connector. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF»(/chevrolet/chevy-van-g2500/1996-1998/remont/removal-installation/#engine-controls-removal-installation-overhaul-43l__fuel-system-pressure-relief) under FUEL SYSTEM.
2. Disconnect throttle and cruise control cables from throttle lever cam and bracket. Disconnect power brake and crankcase ventilation valve vacuum hoses at upper manifold and valve cover. Disconnect electrical harness connectors from TP sensor, IAC valve and MAP sensor.
3. Disconnect No. 1 plug wire from distributor cap. Remove fuel pipe clip retaining bolt. Remove injector fuel inlet and outlet pipe retainer and nuts. Remove upper manifold assembly, attaching bolts and rear mounting nuts (position canister purge solenoid bracket to one side).

Disassembly

1. When cleaning or replacing upper manifold assembly, remove throttle cable bracket attaching bolts and bracket, throttle body assembly, MAP sensor, crankcase ventilation valve, purge solenoid and power brake booster vacuum pipe fitting. CAUTION: DO NOT soak upper manifold assembly in an immersion type cleaner or any cleaner containing MEK.
2. Upper manifold assembly contains TP sensor, IAC valve and internal throttle shaft sealed ball bearings. These components MUST NOT be subjected to strong solvent or cleaner bath. Clean throttle bore and valve deposits with carburetor cleaner and a shop towel. Use care when cleaning gasket surfaces. Sharp tools may damage sealing surfaces.

To install, reverse removal procedure. Tighten upper manifold assembly mounting nuts to 83 INCH lbs. (10 N.m) using an alternating, diagonal pattern starting from the center.

1. Remove air cleaner assembly. Disconnect electrical connector from TP sensor. Remove attaching screws, lock washers, retainers, and TP sensor.
2. To install, reverse removal procedure. Adjust TP sensor to specification. See the «ADJUSTMENTS - 4.3L»(/chevrolet/chevy-van-g2500/1996-1998/remont/adjustments/#engine-performance-system-adjustments-43l) article. When replacing a TP sensor, ensure correct part number is used. Use Loctite on TP sensor attaching screws.

OXYGEN SENSOR

1. Oxygen sensor is mounted in the exhaust pipe, below exhaust manifold. Ensure sensor is free of contaminants. DO NOT use cleaning solvents of any type. Sensor may be difficult to remove when engine temperature is less than 120°F (48°C). Excessive removal force may damage threads in exhaust manifold or pipe.
2. Disconnect negative battery cable. Disconnect electrical connector from oxygen sensor. Carefully remove oxygen sensor from exhaust pipe.

1. Whenever oxygen sensor is removed, coat threads with anti-seize compound before reinstalling. New oxygen sensors already have this compound applied to threads.
2. Install oxygen sensor in exhaust pipe and tighten sensor to 30 ft. lbs. (41 N.m). Reconnect electrical connector to oxygen sensor. Reconnect negative battery cable.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• 4.3L V6 - TRUCKS
• ADJUSTMENTS - 4.3L
• POWERTRAIN CONTROL MODULE (PCM)
• FUEL SYSTEM PRESSURE RELIEF