NOTE: Install tachometer when checking auxiliary air valve system. Ensure tachometer is connected to proper terminals. See IDLE SPEED & MIXTURE in articles listed below for tachometer connections:

ADJUSTMENTS - 4-CYL
ADJUSTMENTS - V6
CAUTION: Some tachometers may not be compatible with ignition system. Consult tachometer manufacturer before connecting tachometer to system. To avoid possible damage to ignitor and/or coil, DO NOT allow tachometer terminal to become grounded.
1. Install tachometer. With engine coolant temperature less than 176°F (80°C), start engine.
2. With engine idling, turn idle speed adjusting screw inward to bottom of bore while counting number of revolutions. See Fig 1 and Fig 2. Engine speed should decrease noticeably.
3. Return idle speed adjusting screw to original position. Warm engine to normal operating temperature. Repeat step 2). Engine speed should not change or should drop slightly.
4. If engine RPM does not respond as indicated, check for vacuum leaks or restricted auxiliary air valve circuit. If no defects are found, replace auxiliary air valve, located on bottom of valve body.

Fig 1: Idle Speed Adjusting Screw ID (2.4L)

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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.

Safety Warning

Auxiliary Air Valve System

Use the Manual With the Right Hardware

When to See a Mechanic

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