* Spark:
* Weak spark: Worn spark plugs, bad ignition coil(s), failing ignition module, or low battery voltage can all result in a weak spark insufficient to ignite the air/fuel mixture. Check spark at each plug individually with an inline spark tester.
* No spark: This points to a more serious problem in the ignition system – a faulty coil, distributor (if equipped), crankshaft position sensor (CKP), camshaft position sensor (CMP), or ignition control module (ICM).
* Fuel:
* No fuel: Check the fuel pump (listen for it to prime when the key is turned to the "on" position), fuel filter, and fuel pressure. A clogged fuel filter or a failed fuel pump will prevent fuel from reaching the engine. Low fuel pressure can also cause starting problems.
* Incorrect fuel/air mixture: A faulty mass airflow sensor (MAF), throttle position sensor (TPS), or other sensors can cause an incorrect air-fuel ratio, preventing combustion.
* Compression:
* Low compression: Worn piston rings, valve problems, or a blown head gasket can lead to insufficient compression, preventing the engine from starting. A compression test is needed to diagnose this.
* Timing:
* Incorrect timing: While you mentioned the firing order is correct, the overall timing of the engine might be off. This is usually adjusted with a timing light.
* Other issues:
* Crankshaft position sensor (CKP) or camshaft position sensor (CMP) issues: These sensors tell the computer the engine's rotational position, crucial for proper ignition timing. Faulty sensors can prevent starting.
* Battery: A weak or dead battery won't provide enough power to crank the engine. Test the battery voltage.
* Starter motor: A faulty starter won't crank the engine, even if everything else is working correctly.
* Security system: Some vehicles have anti-theft systems that can prevent starting if the key isn't recognized.
Troubleshooting Steps:
1. Check the basics: Battery voltage, fuel level, and obvious physical obstructions.
2. Verify spark: Test spark at each plug using an inline spark tester.
3. Check fuel pressure: Use a fuel pressure gauge to measure fuel pressure.
4. Perform a compression test: This will indicate the health of the cylinders.
If you're not comfortable performing these checks yourself, take the vehicle to a qualified mechanic for diagnosis and repair. Trying to troubleshoot without the proper knowledge and tools could lead to further damage.
