1. Verify the Replacement Parts:
* Correct Parts: Double-check you installed the *correct* spark plugs, wires, and coil pack for your specific 2.4L Chevy Cavalier engine. A seemingly minor incompatibility can cause issues.
* Installation: Ensure everything is properly seated and connected. A loose wire, poorly seated plug, or even a slightly damaged coil pack connector can lead to misfires. Visually inspect everything again.
2. Investigate Further:
* Injector #2: A clogged or faulty injector on cylinder #2 is a prime suspect. This is a common cause of misfires. You might need to have the injectors tested (flow tested) or even replaced.
* Compression Test: A compression test will check the cylinder's ability to compress air. Low compression indicates problems with the valves, piston rings, or head gasket.
* Vacuum Leak: A leak in the intake manifold or vacuum lines can disrupt air/fuel mixture, leading to a misfire. Inspect all vacuum lines carefully for cracks or disconnections.
* ECM/PCM (Engine Control Module/Powertrain Control Module): Though less likely after replacing ignition components, a faulty ECM could be misinterpreting sensor data or sending incorrect signals, causing a misfire. This is a more advanced diagnostic that usually requires a professional scan tool.
* Camshaft Position Sensor (CMP) or Crankshaft Position Sensor (CKP): These sensors tell the engine's computer where the pistons are. If they're faulty, the timing could be off, resulting in misfires.
* ETS Light: This is a crucial piece of information. The Electronic Throttle System light being on suggests a problem with the throttle body or related sensors (throttle position sensor, etc.). A malfunctioning throttle system can indirectly affect engine performance and contribute to misfires.
* Fuel Pressure: Low fuel pressure can starve the engine of fuel, leading to misfires. A fuel pressure test might be necessary.
3. Diagnostic Tools:
* OBD-II Scanner: While you've addressed the P0302 code (cylinder 2 misfire), an OBD-II scanner can provide more detailed information, including any other error codes related to the ETS light or other sensors. A more advanced scanner can provide live data, which is useful for troubleshooting.
* Professional Mechanic: If you've exhausted the above steps, it's best to take your Cavalier to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately and efficiently.
Important Note: Continuing to drive the car with a misfire can cause significant damage to the catalytic converter. It's recommended to limit driving until the problem is resolved.
