1. Injector Issues: A faulty injector on cylinder 1 could be preventing proper fuel delivery. This is a common cause of misfires. You can test this with an injector diagnostic tool or have a mechanic perform an injector flow test.
2. Ignition Coil: Even if your distributor cap and rotor are new, the ignition coil itself (or the coil wire to cylinder 1 specifically) might be failing. A failing coil will often cause misfires on a single cylinder. Testing the coil's output is necessary.
3. Worn or Damaged Valves: A worn valve, bent pushrod, or a problem with the rocker arm on cylinder 1 can prevent proper valve operation, leading to a misfire. This requires a more in-depth mechanical inspection of the engine.
4. Compression Issues: Low compression in cylinder 1 indicates a mechanical problem within the cylinder itself (worn piston rings, damaged piston, blown head gasket, etc.). A compression test is crucial to rule this out.
5. Vacuum Leaks: While less likely to cause a misfire on just one cylinder, a significant vacuum leak can disrupt the engine's air/fuel mixture and potentially trigger a misfire. A thorough visual inspection of vacuum hoses and connections is recommended.
6. PCM (Powertrain Control Module) Issues: Though less frequent, a faulty PCM could incorrectly signal the injector or ignition system, resulting in a misfire. This requires advanced diagnostic tools to check.
7. Crank Sensor or Cam Sensor: These sensors are crucial for ignition timing. A faulty sensor can cause misfires, especially if the sensor is failing intermittently.
Troubleshooting Steps:
1. Visual Inspection: Carefully examine the spark plug well for cylinder 1, checking for signs of oil or coolant contamination which could indicate a head gasket leak.
2. Compression Test: This is the most important step next. A low compression reading on cylinder 1 confirms a significant internal engine problem.
3. Injector Test: Test the injector for proper flow and spray pattern.
4. Ignition Coil Test: Test the coil for proper voltage output.
5. Vacuum Leak Check: Inspect all vacuum hoses and connections for cracks, leaks, or loose connections.
Recommendation:
Unless you have experience working on engines, taking your Tahoe to a qualified mechanic is strongly recommended. A proper diagnosis requires specialized tools and expertise to identify the root cause of the misfire beyond simply replacing basic ignition components. Ignoring a misfire can lead to further engine damage.
