Possible Causes
* Spark System Issues:
* Spark Plugs: Worn, fouled, or damaged spark plugs prevent ignition.
* Spark Plug Wires: Cracked, corroded, or loose spark plug wires can interrupt the spark flow.
* Ignition Coils: A faulty ignition coil won't send the high-voltage spark to the spark plug.
* Ignition Control Module (ICM): The ICM controls the spark timing and can fail, causing misfires.
* Timing Issues:
* Timing Belt/Chain: A broken or slipped timing belt/chain disrupts the timing of the engine, preventing proper combustion.
* Camshaft Position Sensor: A faulty sensor won't provide the engine control unit (ECU) with accurate timing information.
* Fuel System Issues (Though you mentioned it's working, check for these):
* Fuel Pressure: A weak fuel pump or clogged fuel filter can reduce fuel pressure, preventing proper fuel delivery.
* Fuel Injectors: Clogged or faulty injectors may not be delivering fuel effectively.
* Engine Sensors:
* Crankshaft Position Sensor: A faulty sensor won't tell the ECU when to trigger the spark, leading to no start.
* Other Sensors: Other sensors (like the oxygen sensor, mass airflow sensor) can contribute to issues that prevent the engine from running smoothly.
* Engine Management System (ECU): A faulty ECU can prevent the engine from starting or running properly.
Troubleshooting Steps
1. Check for Spark:
* Safety First: Disconnect the battery terminal before working on the spark system.
* Remove a Spark Plug: Remove one spark plug wire and connect a spark plug tester to it. Have someone crank the engine while you observe the tester. A strong, blue spark should be present. If not, check the spark plug wires, ignition coils, and ICM.
2. Inspect Timing Belt/Chain:
* Visible Damage: Look for any visual signs of wear, cracks, or missing teeth on the timing belt or chain.
* Tension: If the belt/chain is loose, it could be slipping.
3. Check Fuel System:
* Fuel Pressure: Use a fuel pressure gauge to measure fuel pressure at the fuel rail while someone cranks the engine. The pressure should be within the manufacturer's specifications.
* Fuel Pump Operation: Listen for the fuel pump priming sound when you turn the key to the "On" position.
* Fuel Injector Operation: Check the injectors for leaks or signs of clogging.
4. Inspect Engine Sensors:
* Crankshaft Position Sensor: Inspect the sensor for damage or corrosion.
* Other Sensors: Check other relevant sensors for signs of malfunction.
5. Diagnostic Tool:
* A code reader can help diagnose issues related to the ECU or other sensors.
Important Notes:
* Safety: Always disconnect the battery terminal before working on electrical components.
* Professional Assistance: If you're not comfortable with automotive repairs, it's recommended to seek professional help from a qualified mechanic.
Let me know if you'd like more detailed information on any of these troubleshooting steps. Good luck!
