* Faulty Fuel Injector (Despite Replacement): While you replaced it, the *new* injector could be defective. It's rare, but possible. Check the injector's resistance (using a multimeter) to ensure it's within the manufacturer's specifications. Also, consider if the injector is correctly seated and securely connected.
* Worn or Damaged Spark Plug Wires/Coil Pack: Even with a new spark plug, if the wire leading to it is damaged, cracked, or poorly connected (high resistance), the spark won't be strong enough. Inspect the wire visually for damage, and if possible, measure its resistance. The coil pack itself (which supplies power to multiple cylinders, including #5) could also be failing. A failing coil pack often results in misfires in the cylinders it controls.
* Compression Issue: Low compression in cylinder 5 means the fuel/air mixture isn't being compressed effectively for proper combustion. This requires a compression test. Low compression could indicate worn piston rings, a blown head gasket, or valve problems.
* Vacuum Leak: A significant vacuum leak can disrupt the air/fuel mixture, leading to misfires. Inspect all vacuum lines and hoses for cracks, leaks, or disconnections, especially around the intake manifold and throttle body.
* Clogged Catalytic Converter: A severely clogged catalytic converter can create backpressure, affecting exhaust flow and potentially causing misfires. This is less likely to cause a misfire in just one cylinder, but it's worth considering if multiple cylinders are affected or if there are other exhaust-related issues.
* PCM/ECM Issue (Powertrain Control Module/Engine Control Module): The PCM controls fuel injection and ignition timing. A faulty PCM can cause misfires by sending incorrect signals to the fuel injectors or ignition system. This is more difficult to diagnose and usually requires professional diagnostic tools.
* Wiring Harness Problems: Damaged or corroded wiring in the harness leading to the fuel injector or coil pack for cylinder 5 can interrupt the electrical signal. Carefully inspect the wiring for any signs of damage.
Troubleshooting Steps:
1. Visual Inspection: Carefully examine the spark plug wire, coil pack (if applicable), fuel injector connector, and surrounding wiring for any visible damage.
2. Resistance Testing: Use a multimeter to test the resistance of the spark plug wire and the fuel injector. Compare your readings to the manufacturer's specifications.
3. Compression Test: Perform a compression test on all cylinders to identify if cylinder 5 has significantly lower compression than the others.
4. Vacuum Leak Test: Use a smoke machine or a vacuum gauge to check for vacuum leaks.
5. Diagnostic Scan: Use an OBD-II scanner to retrieve any diagnostic trouble codes (DTCs) from the PCM. This can give you valuable clues about the root cause.
If you're not comfortable performing these checks yourself, take the Camaro to a qualified mechanic. Providing them with the information that you've already replaced the injector and spark plug will help them focus their diagnosis on the other potential issues.
