Fuel System Problems:
* Clogged Fuel Filter: A dirty fuel filter restricts fuel flow, leading to sputtering, especially under acceleration. This is a relatively cheap and easy fix.
* Weak Fuel Pump: The fuel pump might not be delivering enough fuel pressure, especially under load. This is more common in higher-mileage vehicles. You might hear a whining noise from the fuel pump area.
* Clogged Fuel Injector(s): One or more injectors might be partially blocked, preventing sufficient fuel from reaching the cylinders. This can cause sputtering and rough running. Cleaning or replacing injectors is a more involved repair.
* Low Fuel Pressure: Problems with the fuel pressure regulator can cause inconsistent fuel pressure.
* Bad Fuel Pump Relay: The relay that controls the fuel pump might be failing, intermittently cutting power to the pump.
Ignition System Problems:
* Failing Ignition Coil(s): A failing ignition coil can cause misfires in one or more cylinders, leading to sputtering.
* Worn Spark Plugs or Wires: Worn spark plugs or damaged spark plug wires can prevent a consistent spark, resulting in misfires and sputtering. These are relatively easy to check and replace.
* Distributor Cap and Rotor (if equipped): Older vehicles with distributors can have problems with worn or cracked distributor caps and rotors, leading to poor spark delivery. (The LeSabre's engine might not have a distributor, depending on the engine type, but it's worth considering if it does).
* Crankshaft Position Sensor (CKP) or Camshaft Position Sensor (CMP): These sensors tell the engine's computer the position of the crankshaft and camshaft. If they're failing, the timing of the spark can be off, leading to misfires and sputtering.
Other Potential Issues:
* Mass Airflow Sensor (MAF) Sensor: A faulty MAF sensor provides inaccurate air readings to the engine computer, leading to a poor air/fuel mixture.
* Throttle Position Sensor (TPS): A faulty TPS provides incorrect throttle position readings, potentially causing a lean fuel mixture under acceleration.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the air/fuel mixture and cause sputtering.
Troubleshooting Steps:
1. Check the obvious: Start with the easiest and cheapest solutions. Inspect the fuel filter for dirt or debris. Check the spark plugs and wires for wear and tear.
2. Listen for unusual noises: Pay attention to any unusual noises coming from the engine or fuel system.
3. Check engine codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored by the engine computer. These codes can pinpoint the problem.
4. Professional Diagnosis: If you can't identify the problem yourself, take the car to a qualified mechanic for diagnosis and repair.
It's difficult to pinpoint the exact cause without further information or diagnostics, but these are the most likely culprits. Start with the simpler checks and work your way toward more involved repairs. The OBD-II codes will be invaluable in narrowing down the possibilities.
