Fuel Delivery:
* Fuel Pump: A failing fuel pump can't provide consistent fuel pressure, especially when the engine is hot.
* Fuel Filter: While you replaced it, it's possible it was already contaminated and the new one is now blocked.
* Fuel Injectors: Dirty or faulty fuel injectors can cause poor fuel delivery and uneven combustion.
* Fuel Pressure Regulator: A faulty regulator could lead to inconsistent fuel pressure.
Ignition System:
* Distributor: You replaced the cap and rotor, but the distributor itself could be worn or have internal issues.
* Ignition Module: A failing ignition module can prevent sparks from reaching the plugs.
* Crank Sensor: A faulty crank sensor won't accurately tell the computer when to fire the spark plugs.
Engine Components:
* Vacuum Leaks: Leaks in hoses or gaskets can disrupt the air/fuel mixture.
* Intake Manifold Gasket: A worn gasket can cause leaks, impacting fuel mixture.
* Compression Issues: Low compression in one or more cylinders can lead to rough running.
* Valve Train Issues: Worn valve guides or rocker arms can cause valves to stick or fail to seat properly.
Other Considerations:
* Coolant Temperature Sensor: A faulty sensor can provide inaccurate readings to the engine control unit (ECU), leading to erratic fuel delivery.
* Throttle Position Sensor: A faulty throttle position sensor can cause the ECU to misinterpret the throttle position, resulting in poor engine response.
* Engine Control Unit (ECU): While rare, an issue with the ECU itself could cause these problems.
Troubleshooting Steps:
1. Check for Codes: Use an OBD-II scanner to check for any engine codes.
2. Inspect for Vacuum Leaks: Visually inspect all hoses and gaskets for cracks, splits, or leaks.
3. Test Fuel Pressure: Check fuel pressure at the fuel rail to ensure it's within specifications.
4. Inspect Fuel Injectors: If possible, check the injectors for proper operation or have them cleaned.
5. Perform a Compression Test: This will reveal if there's a compression issue in any cylinder.
6. Test Crank Sensor: If equipped with a sensor, test it for proper function.
7. Inspect Ignition System: Thoroughly check the distributor, ignition module, and wiring.
Additional Tips:
* Use a Mechanic's Stethoscope: It can help identify noises from various engine components.
* Perform a Cylinder Leakage Test: This can help isolate the source of a vacuum leak.
* Consult a Repair Manual: A manual specific to your vehicle will provide detailed information about troubleshooting and repair procedures.
It's recommended to consult a qualified mechanic for a proper diagnosis if you're unable to pinpoint the issue. They'll have the tools and expertise to properly assess and repair your Rodeo.
