* Compression Issues: Low compression prevents the engine from igniting the fuel-air mixture even with spark. A compression test is crucial here. Worn piston rings, blown head gasket, or valve problems can all cause low compression.
* Timing Issues: The ignition timing could be significantly off. The spark plugs might be firing at the wrong time relative to the piston position, preventing combustion. This would require a timing check, potentially involving a timing light.
* Crank Position Sensor (CPS): This sensor tells the computer the position of the crankshaft. A faulty CPS will prevent the engine from getting the correct signal to fire the spark plugs at the right time.
* Cam Position Sensor (CMP): Similar to the CPS, a faulty CMP will prevent proper timing.
Troubleshooting Steps:
1. Compression Test: This is the *most important* next step. A mechanic can perform this test relatively quickly and cheaply, giving you a clear indication of whether you have sufficient compression in each cylinder. Low compression in one or more cylinders points directly to a significant engine problem.
2. Check the Timing: If the compression is good, then timing is a suspect. This usually requires specialized tools and knowledge.
3. Inspect the Crank Position Sensor (CPS) and Cam Position Sensor (CMP): These sensors are relatively inexpensive and easy to replace if found faulty. A mechanic can test them or you can try replacing them if you're comfortable with basic car repairs.
4. Verify Fuel Injectors are Working Correctly: Even though you're getting fuel, a faulty injector could be delivering insufficient fuel or not spraying it effectively. A fuel pressure test and injector diagnostic test would be helpful.
5. Check for any Engine Codes: Use an OBD-II scanner to check for any diagnostic trouble codes (DTCs). These codes can offer valuable clues about the problem.
Important Note: Starter fluid should only be used as a diagnostic tool, *not* as a long-term solution. It's highly flammable and can be dangerous.
If you're not comfortable performing these checks yourself, take your Tahoe to a qualified mechanic for diagnosis and repair. Trying to fix a car without the proper knowledge and tools can lead to further damage and unnecessary costs.
