* Dirty or Faulty Mass Airflow Sensor (MAF): The MAF sensor measures the amount of air entering the engine. A dirty sensor provides inaccurate readings, leading to a rough idle or stalling.
* Dirty or Faulty Throttle Position Sensor (TPS): The TPS tells the engine control module (ECM) the position of the throttle. A dirty or faulty TPS can cause erratic idling.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the air-fuel mixture, resulting in poor idling. These leaks can be anywhere in the intake system, hoses, or even the intake manifold gasket.
* Faulty Idle Air Control (IAC) Valve: The IAC valve regulates the amount of air entering the engine at idle. A malfunctioning IAC valve can cause erratic idling or stalling.
* Dirty or Clogged Fuel Injectors: Clogged injectors can prevent the proper delivery of fuel, leading to a rough idle.
* Spark Plugs and Wires: Worn-out spark plugs or damaged ignition wires can cause misfires, resulting in a rough idle.
* Failing Engine Coolant Temperature (ECT) Sensor: An inaccurate ECT sensor reading can cause the ECM to adjust the air-fuel mixture improperly.
* Low Compression: Low compression in one or more cylinders will lead to a rough idle and loss of power.
* Problem with the PCM/ECM: While less common, a faulty engine control module can cause a wide range of problems, including idling issues.
To help diagnose the problem:
* Check the engine codes: Use an OBD-II scanner to retrieve any diagnostic trouble codes (DTCs) stored in the ECM. These codes can point to the source of the problem.
* Inspect visually: Look for any obvious signs of damage, such as loose or damaged vacuum hoses, or signs of leaks.
* Listen to the engine: Pay attention to any unusual noises coming from the engine. A ticking or knocking sound could indicate a mechanical problem.
Since diagnosing this requires hands-on mechanical knowledge and tools, it's strongly recommended to take your 1997 Buick Century to a qualified mechanic for proper diagnosis and repair. Attempting repairs without the proper knowledge and tools could potentially worsen the problem.
