Here are some of the *most common* causes of a rough-running engine and a check engine light in a vehicle of that age and model:
* Spark Plugs and Wires: Worn or fouled spark plugs are a very common culprit. Worn spark plug wires can also cause misfires and a rough idle.
* Ignition Coil(s): These can fail, leading to misfires in one or more cylinders. A failing coil often produces a rough idle that worsens under load.
* Mass Airflow Sensor (MAF) Sensor: This sensor measures the amount of air entering the engine. A faulty MAF sensor can cause a lean or rich air/fuel mixture, resulting in a rough idle and poor performance.
* Throttle Position Sensor (TPS): This sensor tells the computer the throttle position. A faulty TPS can cause erratic idling and poor throttle response.
* Oxygen Sensor(s): These sensors measure the oxygen in the exhaust and help regulate the air/fuel mixture. A bad oxygen sensor can lead to a rough idle and poor fuel economy.
* Vacuum Leaks: Leaks in the intake manifold or vacuum hoses can disrupt the air/fuel mixture, causing a rough idle.
* Catalytic Converter: A failing catalytic converter can restrict exhaust flow, leading to rough running and a check engine light.
* PCV Valve: A faulty positive crankcase ventilation (PCV) valve can cause excessive pressure in the crankcase, leading to various problems, including a rough idle.
* Fuel Injectors: Clogged or malfunctioning fuel injectors can prevent proper fuel delivery to the cylinders.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the position of the crankshaft. A faulty CKP sensor will prevent the engine from starting or running properly.
* Cam Position Sensor (CMP): Similar to the CKP sensor, but for the camshaft. A faulty CMP can cause misfires and rough running.
Without the DTC codes, any attempt to diagnose the problem is just guessing. Get the codes read, and then you can research the specific codes to narrow down the potential causes. Once you have the codes, you can search online (or consult a repair manual) for possible causes. Remember, even with the codes, diagnosis may require some mechanical expertise or a professional mechanic.
