Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISENGINE PERFORMANCEREMOVE, OVERHAUL & INSTALLENGINE CONTROLS - REMOVAL & INSTALLATIONAIR INDUCTION SYSTEMSINTAKE MANIFOLDINSTALLATION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Intake Manifold: Installation
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Installation
Install intake manifold using a NEW gasket. Tighten fasteners to specification. See TORQUE SPECIFICATIONSΒ . To complete installation, reverse removal procedure.
- Install NEW intake manifold gaskets (1) to the intake manifold. See Fig 13.
- Install the intake manifold. See Fig 12.
- Apply a 0.20" (5 mm) bead of Threadlock (GM P/N 12345382) to the threads of the intake manifold bolts.
- Install the intake manifold bolts.
- Tighten the bolts a first pass in sequence to 44 INCH lbs (5 N.m). See Fig 14.
- Tighten the bolts a final pass in sequence to 89 INCH lbs. (10 N.m).
- Route the electrical harness into position over the engine.
- Install the engine harness bracket nut (1). See Fig 11. Tighten the nut to specification. See TORQUE SPECIFICATIONSΒ .
- Install the vacuum brake booster hose to the rear of the intake manifold. See Fig 10.
- Install the EVAP purge solenoid vent tube. See Fig 9.
- Install the heater water shutoff valve actuator inlet hose to the intake manifold. See Fig 8.
- Install the PCV hose. See Fig 7.
- Install the knock sensor harness electrical connector to the intake manifold.
- Connect the following electrical connectors:
- EVAP purge solenoid (1). See Fig 6.
- Knock sensor (2).
- MAP sensor (3).
- Main coil (5).
- Fuel injectors (4).
- 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. See Fig 4.
- Repeat the steps for each injector electrical connector.
- Install the harness clips to the fuel rail.
- Connect the generator electrical connector. See Fig 5.
- Connect the following electrical connectors:
- Main coil (1). See Fig 3.
- ETC (2).
- Fuel injectors (3).
- Install the electrical harness clips to the fuel rail.
- Connect the A/C compressor pressure switch electrical connector (2). See Fig 1.
- Install the harness clip to the cylinder head.
- Connect the MAF/IAT sensor electrical connector (1). See Fig 2.
- Install the air cleaner outlet duct. See AIR CLEANER RESONATOR OUTLET DUCTΒ .
- Install the fuel fill cap.
- Connect the negative battery cable.
- Use the following procedure in order to inspect for leaks:
- Turn the ignition ON, wit 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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.