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.
Diagnostic Aids
Inspect for the following conditions:
- A skewed high Throttle Position (TP) sensor.
- Restricted air intake system.
- Objects blocking the IAC passage or throttle bore.
- The correct Positive Crankcase Ventilation (PCV) valve.
- A properly installed PCV valve.
- Proper operation of the PCV valve.
- Proper operation and installation of all air intake components.
- Proper installation and operation of the Mass Air Flow (MAF) sensor, if equipped.
- Evidence of damage or tampering of the following components:
- The throttle stop screw.
- The throttle plate.
- The throttle shaft.
- The throttle linkage.
- The cruise control linkage, if equipped.
- Excess deposits in the IAC passage or on the IAC pintle.
- Excess deposits in the throttle bore or on the throttle plate Vacuum leaks.
- Excess load on engine, such as energy-draining conditions of the transmission, power steering, or alternator.
- A high or unstable idle condition. This condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve. See TROUBLE SHOOTING - NO CODES - TRUCKS article.
- A low or unstable idle condition. This condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve. See TROUBLE SHOOTING - NO CODES - TRUCKS article.
- An intermittent condition.
| Engine | Maximum RPM Less Than Commanded RPM | Maximum RPM More Than Commanded RPM |
|---|---|---|
| 2.2L (A/T) | 60 | 60 |
| 2.2L (M/T) | 100 | 60 |
| 3.4L | 100 | 150 |
| 4.3L, 4.8L, 5.0L, 5.3L, 5.7L & 6.0L | 100 | 200 |
Use the Manual With the Right Hardware
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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.
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