1. Verify Installation:
* Correct Installation: Double-check that all new parts are correctly installed. A single misplaced wire or improperly seated rotor can cause a rough idle. Consult a wiring diagram specific to your 1988 Corvette's engine (either a small-block or a big-block). Pay close attention to the firing order.
* Rotor Alignment: Ensure the rotor is correctly aligned with the distributor shaft and pointing to the correct cylinder at the #1 spark plug wire.
* Cap Securement: Make sure the distributor cap is securely fastened. A loose cap can lead to poor connection.
* Wire Routing: Ensure the spark plug wires are correctly routed to avoid interference and are firmly attached to both the cap and spark plugs.
2. Ignition System Components (Beyond Rotor, Cap, and Wires):
* Distributor: The distributor itself could be worn or failing. Check the mechanical advance mechanism for smooth operation. A sticking or faulty mechanism will cause inconsistent timing.
* Ignition Coil: A failing ignition coil can produce a weak spark, leading to a rough idle. Testing the coil's output is crucial. This typically requires a multimeter or specialized ignition testing equipment.
* Pick-up Coil (in the distributor): This component senses the position of the rotor and signals the ignition module. A faulty pick-up coil can cause misfires and rough running.
* Ignition Module (ECM): The ECM (Engine Control Module) is the "brain" of the ignition system. While less likely to be directly caused by the parts replacement, a failing ECM can still influence the ignition timing and overall performance.
* Spark Plugs: Even with new wires, the spark plugs themselves might be faulty or improperly gapped. Check the gap specification and replace them if needed.
3. Other Potential Issues:
* Vacuum Leaks: A vacuum leak in the intake manifold or vacuum lines can disrupt the air/fuel mixture, resulting in a rough idle. Check all vacuum lines for cracks or looseness.
* Throttle Position Sensor (TPS): A faulty TPS can provide inaccurate information to the ECM, affecting fuel delivery and idle speed.
* Air Flow Meter (AFM): Similar to the TPS, a faulty AFM will also lead to an incorrect air/fuel mixture calculation.
Troubleshooting Steps:
1. Re-check all connections: Start by meticulously checking your work again. This is the most likely culprit if the problem started immediately after the replacement.
2. Listen to the engine: Pay close attention to the engine sounds to isolate which cylinder(s) might be misfiring.
3. Use a timing light: A timing light will help you verify if the ignition timing is correct.
4. Use a multimeter: Test the ignition coil, and possibly the pick-up coil if you have the equipment and experience.
5. Obtain a service manual: A factory service manual for your 1988 Corvette will provide detailed wiring diagrams, diagnostic procedures, and specifications.
If you're not comfortable working on the ignition system yourself, it's best to take the car to a qualified mechanic. Improperly diagnosing or repairing an ignition system can lead to further damage.
