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 DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 142 (ENGINE CONTROL SYSTEM TESTING & ENGINE COMPONENT TESTING)IDLE CONTROL SYSTEMSIDLE AIR CONTROL SYSTEM (2.2L, 2.4L, 3.1L, 3.4L, 3.5L, 3.8L, 4.0L & 4.6L)DIAGNOSTIC AIDS
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Diagnostic Aids
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2002 Saturn SL2, 2002 Saturn SL1, 2002 Saturn SL, 2002 Saturn SC2, and 2002 Saturn SC1. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for the following conditions:
- Skewed high TP sensor.
- Restricted air intake system.
- Objects blocking IAC passage or throttle bore.
- Correct Positive Crankcase Ventilation (PCV) valve, properly installed and proper operation of PCV valve (if equipped).
- Proper operation and installation of all air intake components.
- Proper installation and operation of Mass Air Flow (MAF) sensor (if equipped).
- Tampered with or damaged throttle stop screw.
- Tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage (if equipped).
- Excessive deposits in IAC passage or on IAC pintle.
- Excessive deposits in throttle bore or on throttle plate.
- Vacuum leaks
- Excessive engine load caused by faulty transmission, power steering, alternator, etc.
- High or unstable idle condition caused by a non-IAC system problem that can not be overcome by IAC valve.
- Low or unstable idle condition caused by a non-IAC system problem that can not be overcome by IAC valve.
RPM VARIATION LIMITS
| Engine | Maximum RPM Less Than Commanded RPM | Maximum RPM More Than Commanded RPM |
|---|---|---|
| 2.2L & 2.4L (M/T) | 60 | 100 |
| 2.2L & 2.4L (A/T) | 60 | 60 |
| 3.1L & 3.4L | 100 | 150 |
| 3.5L | 75 | 75 |
| 3.8L | 100 | 175 |
| 4.0L & 4.6L | 100 | 100 |
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.