Fuel System:
* Clogged Fuel Filter: A dirty fuel filter restricts fuel flow, leading to inconsistent engine performance and bucking. This is a relatively inexpensive and easy fix.
* Fuel Pump Issues: A failing fuel pump may not deliver sufficient fuel pressure, especially under acceleration demands. You might hear a whining sound from the fuel pump if it's failing.
* Bad Fuel Injectors: Clogged or faulty injectors can cause a misfire in one or more cylinders, resulting in a bucking sensation. A diagnostic scan can often reveal this.
* Low Fuel Pressure: Problems with the fuel pressure regulator can lead to inconsistent fuel delivery.
* Fuel Pressure Sensor: An inaccurate reading from this sensor can cause the engine to receive the wrong amount of fuel.
Ignition System:
* Worn Spark Plugs or Wires: These are common wear items. Worn plugs can misfire, especially under load. Cracked or damaged wires can lead to a loss of spark.
* Ignition Coil Problems: A failing ignition coil can prevent one or more cylinders from firing correctly.
* Distributor Cap and Rotor (if equipped): Cracks or corrosion in these components can interrupt the spark delivery. (Note: The 5.9L may or may not have a distributor, depending on the specific engine configuration). If it has a distributor, this is a possibility.
* Crankshaft Position Sensor (CKP): This sensor tells the engine's computer the position of the crankshaft. A bad CKP sensor will cause misfires and erratic running.
* Cam Position Sensor (CMP): Similar to the CKP sensor, a faulty CMP sensor will disrupt the timing and cause rough running.
Air Intake System:
* Mass Airflow Sensor (MAF) Sensor: A dirty or faulty MAF sensor provides inaccurate air readings to the engine computer, leading to improper fuel mixture and erratic performance. Cleaning it is often a first step.
* Vacuum Leaks: Leaks in vacuum hoses can disrupt the proper functioning of various engine components, including the fuel system and ignition timing.
* Throttle Position Sensor (TPS): A faulty TPS sends inaccurate throttle position information, causing incorrect fuel delivery.
Other Potential Causes:
* Transmission Problems: While less likely to cause bucking specifically during *acceleration*, a slipping transmission can cause a similar feeling of power loss and jerking.
* Exhaust System Restrictions: A severely clogged catalytic converter or muffler can restrict exhaust flow, affecting engine performance.
* Computer Issues (PCM): In rare cases, a faulty engine control module (PCM) can cause erratic engine behavior. This is usually diagnosed by a mechanic with the proper equipment.
Troubleshooting Steps:
1. Check for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to read any stored codes. This is the most important first step. The codes will often point you directly to the problem.
2. Inspect visually: Check for obvious problems like loose wires, vacuum leaks, and damaged components.
3. Start with the easy and inexpensive fixes: Change the spark plugs and wires, clean the MAF sensor, and check the fuel filter.
4. Check fuel pressure: This requires a fuel pressure gauge and is best left to someone experienced with automotive repair.
5. Consult a repair manual: A factory service manual for your specific Durango model will be extremely helpful.
If you're not comfortable working on your vehicle yourself, it's best to take it to a qualified mechanic for diagnosis and repair. The bucking could indicate a serious problem that needs professional attention.
