* Worn or damaged distributor: Even with new components, the distributor itself could be worn or damaged internally. The shaft might be worn, causing poor timing, or the internal components might be failing.
* Ignition coil: The ignition coil provides the high voltage to the distributor. A failing coil will produce weak or inconsistent sparks, leading to misfires.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational speed and position. A faulty CKP sensor will cause erratic ignition timing, resulting in misfires.
* Camshaft Position Sensor (CMP): Similar to the CKP sensor, a bad CMP sensor will disrupt the timing of the fuel injection and ignition systems leading to misfires.
* Ignition control module (ICM): This module controls the ignition coil and timing. A failing ICM can cause intermittent or consistent misfires.
* Fuel delivery issues: While you're focusing on ignition, a misfire can also be caused by problems with fuel delivery. This could include a clogged fuel filter, low fuel pressure, faulty fuel injectors, or a problem with the fuel pump. Check fuel pressure.
* Vacuum Leaks: A significant vacuum leak can affect the engine's performance and cause misfires, particularly at idle or under load.
* Worn or damaged valve(s): A worn or damaged valve can lead to misfires, though this is less likely if the problem is sudden after replacing ignition components.
* Wiring issues: While you replaced the wires to the plugs, there could be a break or short elsewhere in the ignition system wiring harness.
Troubleshooting Steps:
1. Check for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to read any trouble codes stored in the vehicle's computer. These codes can pinpoint the problem area.
2. Visual inspection: Carefully inspect all ignition components for obvious damage, cracks, or corrosion. Check all wiring connections for tightness and corrosion.
3. Test the ignition coil: There are testing methods for checking the coil's output voltage. This usually involves a multimeter or a spark tester.
4. Test the CKP and CMP sensors: These sensors can be tested using a multimeter or a scan tool that can read their signals.
5. Check fuel pressure: A fuel pressure gauge is needed to ensure proper fuel pressure.
6. Perform a compression test: This will check the health of the engine's cylinders. Low compression in one or more cylinders could indicate a mechanical problem causing misfires.
If you are not comfortable performing these tests yourself, take your vehicle to a qualified mechanic. They have the tools and expertise to diagnose and repair the misfire properly. Throwing parts at it without proper diagnosis can be costly and ineffective.
