Before you begin anything, consult your owner's manual for the specific year and model of your Cavalier. This will give you the most accurate information.
Here's a breakdown of how to approach idle speed adjustment, based on the type of throttle system:
1. Determine the Throttle System:
* Cable-Operated Throttle (Older Cavaliers, likely pre-2000): This is less common on Cavaliers. If you have a throttle cable visibly connected to the throttle body, you *might* have a manual idle adjustment screw. It's usually on the throttle body itself, often a small screw with a lock nut.
* Electronic Throttle Control (ETC) (Most Cavaliers): The throttle is controlled electronically by the computer. There's no user-adjustable idle speed screw.
2. If Cable-Operated (Proceed with Caution):
* Locate the Idle Adjustment Screw: If present, it's usually on the throttle body. It might be hidden under a vacuum line or other components.
* Disconnect the Battery Negative Terminal: This is crucial to prevent damaging the vehicle's computer system.
* Very Small Adjustments: Turn the screw very slightly (less than 1/8th of a turn). Too much adjustment can cause serious problems.
* Check the Idle Speed: After each adjustment, start the engine and check the idle speed with a tachometer (highly recommended). The ideal idle speed is usually specified in your owner's manual.
* Reconnect the Battery: Once the idle speed is correct, reconnect the negative battery terminal.
3. If Electronic Throttle Control (ETC):
* Do NOT attempt to adjust anything manually. There's no accessible screw for adjusting idle speed. Incorrect adjustments can severely damage the system.
* The idle speed is controlled by the engine control module (ECM). Any problem with idle speed is likely due to a sensor malfunction, vacuum leak, or other internal issue.
If you're having idle speed problems, the best course of action is:
* Consult your owner's manual: It will provide the correct idle speed specification and any troubleshooting steps.
* Use a diagnostic scanner (OBD-II): This will help identify any trouble codes related to the idle system. This is especially important for ETC systems.
* Take your car to a qualified mechanic: They have the tools and knowledge to diagnose and repair idle speed issues accurately. Trying to adjust it yourself without understanding the system can lead to more significant problems and expensive repairs.
In short, for most Chevy Cavaliers, attempting to manually adjust the idle speed is likely to be ineffective and potentially harmful. Professional diagnosis is recommended.
