Engine Control System - 5.3L - Introduction: Overhaul GMC Envoy II

Disassembly Procedure

1. Remove the fuel feed pipe from the fuel module and retaining clip.
2. Remove the EVAP solenoid pipe (3) from the vent solenoid valve and the EVAP canister. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200373-S38404922092005102000000) .
3. Remove the EVAP pipe assembly (2) from the fuel tank vent valves, the fuel module, and the EVAP canister. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200373-S38404922092005102000000) .
4. Remove the EVAP canister purge pipe (1) from the EVAP canister and retaining clip. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200373-S38404922092005102000000) .
5. Remove the EVAP vent valve (9). Refer to «Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement»(ref-200373-S30695037232005102000000) .
6. Remove the fuel sender assembly (3) from the fuel tank. Refer to «Fuel Sender Assembly Replacement»(ref-200373-S23845607092005102000000) .
7. Remove the EVAP canister (2). Refer to «Evaporative Emission (EVAP) Canister Replacement (TrailBlazer, Envoy, Rainier)»(ref-200372-S40072272842005102000000) «Evaporative Emission (EVAP) Canister Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV)»(ref-200373-S19833679882005102000000) .

Assembly Procedure

1. Install the EVAP canister (2). Refer to «Evaporative Emission (EVAP) Canister Replacement (TrailBlazer, Envoy, Rainier)»(ref-200372-S40072272842005102000000) «Evaporative Emission (EVAP) Canister Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV)»(ref-200373-S19833679882005102000000) .
2. Install the fuel sender assembly (3) to the fuel tank. Refer to «Fuel Sender Assembly Replacement»(ref-200373-S23845607092005102000000) .
3. Install the EVAP vent valve (9). Refer to «Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement»(ref-200373-S30695037232005102000000) .
4. Install the EVAP canister purge pipe (1) to the EVAP canister and retaining clip. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200373-S38404922092005102000000) .
5. Install the EVAP pipe assembly (2) to the fuel tank vent valves, the fuel module, and the EVAP canister. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200373-S38404922092005102000000) .
6. Install the EVAP solenoid pipe (3) to the vent solenoid valve and the EVAP canister. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200373-S38404922092005102000000) .
7. Install the fuel feed pipe to the fuel module and retaining clip.

1. Cut and remove the tie (2) securing the fuel feed pipe and EVAP canister purge pipe together.
2. Remove the fuel feed pipe (1) from the fuel sender module (4) and retaining clip (3). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200372-S03438683812005102000000) .
3. Cut and remove the tie (1) securing the EVAP pipes together.
4. Disconnect the EVAP pipe assembly (3) from the tank vent valves and fuel sender. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200372-S03438683812005102000000) .
5. Remove the EVAP pipe assembly (3) from the tank.
6. Remove the EVAP canister purge pipe (2) from the fuel tank.
7. Remove the EVAP vent valve (8). Refer to «Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement»(ref-200372-S24136167682005102000000) .
8. Remove the fuel sender assembly (4) from the fuel tank. Refer to «Fuel Sender Assembly Replacement»(ref-200372-S24643162872005102000000) .

1. Install the fuel sender assembly (4) to the fuel tank. Refer to «Fuel Sender Assembly Replacement»(ref-200372-S24643162872005102000000) .
2. Install the EVAP vent valve (8). Refer to «Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement»(ref-200372-S24136167682005102000000) .
3. Install the EVAP canister purge pipe (2) to the fuel tank.
4. Install the EVAP pipe assembly (3) to the fuel tank.
5. Connect the EVAP pipe assembly (3) to the tank vent valves and fuel sender. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200372-S03438683812005102000000) .
6. Install a new tie (1) to secure the EVAP pipes together.
7. Install the fuel feed pipe (1) to the fuel sender module (4) and retaining clip (3). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(ref-200372-S03438683812005102000000) .
8. Install a new tie (2) securing the fuel feed pipe and EVAP canister purge pipe together.

1. Remove the fuel injectors (2) from the fuel rail (5). Refer to «Fuel Injector Replacement»(ref-200373-S18145275142005102000000) .
2. Remove the fuel rail crossover pipe retaining clip screws (8) and retainer clips (9).
3. Remove the fuel rail crossover pipe (10) from the left and right hand fuel rails.
4. Remove and discard the fuel rail crossover pipe O-rings (11).
5. Remove the service port cap (7) and valve (6) from the fuel rail (5).

1. Install the service port cap (7) and valve (6) to the fuel rail (5).
2. Lubricate the NEW fuel rail crossover pipe O-rings (11) with clean engine oil.
3. Install the NEW fuel rail crossover pipe O-rings (11) onto the crossover pipe (10).
4. Install the fuel rail crossover pipe (10) to the left and right hand fuel rails.
5. Install the fuel rail crossover fuel pipe retainer clips (9).
6. Install the fuel rail retainer clip screws (8) but do not tighten at this time.
7. Install the fuel injectors (2) to the fuel rail (5). Refer to «Fuel Injector Replacement»(ref-200372-S17152680902005102000000) .

Scheme 101

1. Lubricate the NEW lower injector O-ring seals with clean engine oil.
2. Install the NEW O-ring seals onto each injector.
3. Install the fuel rail (1).
4. Apply a 5 mm (0.2 in) band of threadlock GM P/N 12345382 (Canadian P/N 10953489) or equivalent, to the threads of the fuel rail bolts (2 and 3).
5. Install the fuel rail bolts (2 and 3). Tighten: Tighten the bolts to 10 N.m (89 lb in).
6. Tighten the fuel rail retainer clip screws. Tighten: Tighten the screws to 3.8 N.m (34 lb in).
7. Connect the fuel feed pipe (1) to the fuel rail. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(ref-200373-S11470256792005102000000) .
8. Position the upper engine wire harness over the engine.
9. Install the upper engine wire harness retainer nut (1). Tighten: Tighten the nut to 5 N.m (44 lb in).
10. Connect the following electrical connectors on the left hand side of the engine: The EVAP purge solenoid (1) The knock sensor (2) The MAP sensor (3) The main coil (5) The fuel injectors (4)
11. Perform the following steps in order to Connect the fuel injector electrical connectors. Install the connectors to their corresponding injectors to ensure correct reassembly. Connect the fuel injector electrical connector. Push the CPA retainer (2) on the connector in 1 click. Repeat the steps for each injector electrical connector.
12. Install the electrical harness to the clips on ignition coil bracket.
13. Connect the following electrical connectors on the right hand side of the engine: The coil main electrical harness (1) The ETC (2) The fuel injectors (3)
14. Install the electrical harness to the clips on ignition coil bracket.
15. Connect the generator electrical connector.
16. Connect the MAF/IAT sensor electrical connector (1).
17. Install the wire harness to the clip (1) on the cylinder head.
18. Connect the A/C compressor pressure switch electrical connector (2).
19. Install the PCV foul air hose.
20. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(ref-200373-S04937318252005102000000)
21. Install the fuel fill cap.
22. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure»(ref-200375-S07741338702005102000000) in Engine Electrical.
23. Use the following procedure in order to inspect for leaks: Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

Valve Lifter Oil Manifold (VLOM) Assembly

The displacement on demand (DoD) system uses an electro-hydraulic actuator device called the valve lifter oil manifold (VLOM) assembly. The VLOM is bolted to the top of the engine valley, below the intake manifold assembly. The VLOM consists of 4 electrically operated Normally Closed Solenoids. Each solenoid controls the application of engine oil pressure to the intake and exhaust valve lifters on the cylinders selected to deactivate. Engine oil pressure is routed to the VLOM assembly from a passage on the rear of the cylinder block.

All 4 VLOM solenoids are connected in parallel to a fused ignition 1 voltage circuit, supplied by the powertrain relay. The ground or control circuit for each solenoid is connected to the engine control module (ECM).

When all enabling conditions are met for DoD operation, the ECM will ground each solenoid control circuit in firing order sequence, allowing current to flow through the solenoid windings. With the coil windings energized, the solenoid valve opens, redirecting engine oil pressure through the VLOM into 8 separate vertical passages in the engine lifter valley. The 8 vertical passages, 2 per cylinder, are connected to the valve lifter bores of the cylinders to be deactivated. When vehicle-operating conditions require a return to V8 mode, the ECM will turn OFF the control circuit for the solenoids, allowing the solenoid valves to close. With the solenoid valves closed, engine oil pressure in the control ports is exhausted through the body of the solenoids into the engine block lifter valley. The housing of the VLOM incorporates several bleeds in the oil passages to purge any air trapped in the VLOM or engine block.

To control any contamination to the DoD hydraulic circuits, a small replaceable oil screen is located in the VLOM oil inlet passage, below the oil pressure sensor. The oil pressure sensor is a 3-wire sensor which provides oil pressure information to the ECM.

During service, use extreme care in keeping the VLOM assembly free of any contamination or foreign material.

Throttle Body Assembly

The throttle assembly contains the following components

1. The throttle blade
2. The throttle actuator motor
3. The throttle position (TP) sensor 1 and 2

The throttle body functions similar to a conventional throttle body with the following exceptions

1. An electric motor opens and closes the throttle valve.
2. The throttle blade is spring loaded in both directions and the default position is slightly open.
3. There are 2 individual TP sensors within the throttle body assembly.

The TP sensors are used to determine the throttle plate angle. The TP sensors provide the engine control module (ECM) with a signal voltage proportional to throttle plate movement. The TP sensor 1 signal voltage at closed throttle is above 4 volts and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is below 1 volt and increases as the throttle plate is opened.