1. Check for Spark:
* Spark Plugs: Ensure they're properly installed and not fouled (blackened with excess fuel).
* Spark Plug Wires: Look for cracks, corrosion, or loose connections.
* Distributor Cap and Rotor: Inspect for wear, cracks, or carbon buildup. Replace if necessary.
* Ignition Coil: Though you replaced it, double-check connections and ensure it's functioning properly.
2. Fuel Delivery:
* Fuel Pump: Make sure the pump is running when the key is turned to the "on" position. You can listen for a humming sound near the fuel tank.
* Fuel Filter: A clogged filter can restrict fuel flow. Replace it if it hasn't been done recently.
* Fuel Lines and Injectors: Check for leaks, blockages, or corrosion.
3. Engine Control Module (ECM):
* Connections: Inspect the ECM connector for corrosion or loose connections.
* Fuses and Relays: Ensure all fuses related to the ignition system and fuel system are intact.
* ECM Programming: If the control module has been replaced or reprogrammed, make sure it's compatible with your car's specifications.
4. Other Considerations:
* Timing Belt: A broken or slipped timing belt can prevent the engine from firing.
* Crankshaft Position Sensor: This sensor tells the ECM the position of the crankshaft. A faulty sensor can cause starting problems.
* Vacuum Lines: Check for leaks in vacuum lines, which can affect fuel/air mixture and ignition timing.
Troubleshooting Tips:
* Use a multimeter: Test for continuity and voltage in the ignition system, fuel pump, and related circuits.
* Listen for clicking sounds: A clicking sound when turning the key might indicate a faulty starter or battery connection.
* Check for codes: Use an OBD-II scanner to retrieve any stored diagnostic trouble codes, which can help narrow down the problem.
Important Note: This information is for general troubleshooting purposes. It's best to consult with a qualified mechanic if you are not comfortable working with electrical systems or if you're unable to resolve the issue.
