1. Identify Your Fuel System:
* Throttle Body Injection (TBI): This is the more likely system for a 1984 Corvette. It uses a single throttle body with injectors spraying fuel directly into the intake manifold. Look for a rectangular throttle body on the intake manifold.
* Carburetor: Less likely for a 1984, but possible on very early models. This will be a round, usually black, device on the intake manifold with various linkages and adjustments.
2. Adjusting the Idle (If TBI):
The 1984 Corvette's TBI system uses a computer to control the idle. There isn't a manual idle adjustment screw like on a carburetor. Manual adjustment is strongly discouraged. Instead of adjusting the idle directly, you should address underlying problems causing an idle issue. These include:
* Clean the throttle body: Dirt and grime can cause erratic idling. Use a throttle body cleaner specifically designed for this purpose and follow the instructions carefully.
* Check the Idle Air Control (IAC) valve: This valve regulates airflow at idle. A dirty or faulty IAC valve can cause idle problems. Cleaning it is often sufficient. Replacement might be necessary if cleaning doesn't solve the problem.
* Inspect the PCV valve: A clogged PCV valve can cause a rough idle. Replace it if necessary.
* Check for vacuum leaks: Vacuum leaks disrupt the air/fuel mixture and can cause idle problems. Inspect all vacuum hoses and connections for cracks or loose fittings.
* Check the MAP sensor: The Manifold Absolute Pressure sensor is crucial for the computer to control the air/fuel mixture. A faulty MAP sensor can cause a range of issues, including idle problems.
* Computer diagnostics: The best approach for TBI systems is to use a scan tool to read diagnostic trouble codes (DTCs). This will point you toward the specific problem causing the idle issue.
3. Adjusting the Idle (If Carburetor):
If, unexpectedly, your 1984 Corvette *does* have a carburetor, the adjustment process will be different and more complex. It involves adjusting the idle speed screw and possibly the mixture screws. This requires a good understanding of carburetor operation and the potential for damaging the engine if done incorrectly.
* Idle Speed Screw: This screw directly controls the idle speed. Turning it clockwise increases idle speed, counter-clockwise decreases it. Small adjustments are crucial; make tiny turns and let the engine settle before making further adjustments.
* Idle Mixture Screws: These screws affect the air/fuel mixture at idle. They are typically found on the carburetor's sides. Adjusting them usually requires special tools and a precise procedure. This is best left to someone with carburetor experience.
Disclaimer: Adjusting the idle, especially on a fuel-injected system, can be complicated and potentially harmful if done incorrectly. If you are not comfortable working on your vehicle's fuel system, take it to a qualified mechanic. Improper adjustments can lead to engine damage or poor performance. Always consult your owner's manual or a repair manual specific to your 1984 Corvette for detailed instructions and safety precautions.
