* Spark Plug/Wire: The spark plug in cylinder #1 is the most obvious suspect. It could be fouled, cracked, worn out, or have a poor connection. The spark plug wire could also be damaged, loose, or corroded. Check for cracks, proper seating, and corrosion.
* Injector: A clogged or faulty fuel injector for cylinder #1 would prevent fuel from reaching that combustion chamber. This is less likely than spark issues, but possible. You'd need a fuel pressure test and possibly an injector flow test to diagnose this accurately.
* Valve Train: A problem with the intake or exhaust valve for cylinder #1 (burnt valve, sticking valve, low compression) can prevent proper combustion. This is a more involved issue requiring a compression test and potentially valve adjustments or more serious repairs.
* Sensor Issues: While less likely to cause a single-cylinder misfire, a faulty crankshaft position sensor (CKP) or camshaft position sensor (CMP) *could* cause a misfire if it's specifically misreading information from cylinder #1's firing event.
* Wiring Harness: There could be a break or short in the wiring harness specifically affecting the components related to cylinder #1. Inspect the harness carefully.
Troubleshooting Steps:
1. Start with the simplest: Visually inspect the spark plug and wire for cylinder #1. Replace the spark plug and wire as a first step. This is the cheapest and easiest fix and often solves the problem.
2. Check for Codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs). This might point to a specific sensor or system problem.
3. Compression Test: If replacing the spark plug and wire doesn't solve the issue, a compression test will reveal if there's a mechanical problem with the cylinder (e.g., a burnt valve, low compression).
4. Fuel Injector Test: If compression is good, consider a fuel injector test to see if cylinder #1's injector is delivering fuel properly.
Important Note: Working on your vehicle's engine involves potential risks. If you're not comfortable performing these diagnostics and repairs, take your Blazer to a qualified mechanic for professional diagnosis and repair. Incorrect diagnosis and repairs could lead to more significant engine damage.
