1. Vacuum Leak: A vacuum leak can cause the engine to run lean (too much air, not enough fuel) when you give it gas, leading to a rough idle. Check for any loose or cracked hoses in the vacuum system, especially around the intake manifold and throttle body.
2. Fuel Filter: A clogged or partially clogged fuel filter can restrict fuel flow to the engine, causing it to run lean and rough under acceleration. Replace the fuel filter if it's dirty or has not been changed recently.
3. Fuel Injector Issues: Malfunctioning or dirty fuel injectors can cause inconsistent fuel delivery, leading to rough running. Have your fuel injectors checked and cleaned or replaced if necessary.
4. Spark Plugs: Worn or fouled spark plugs can cause misfires, especially under load. Check the condition of your spark plugs and replace them if they are worn or damaged.
5. Ignition System Problems: Faulty ignition components, such as spark plug wires, distributor cap, or ignition coil, can cause weak or inconsistent sparks, leading to a rough idle and poor acceleration. Inspect these components for any damage or cracks and replace them if needed.
6. Throttle Body: A dirty or faulty throttle body can disrupt proper air and fuel flow into the engine. Clean the throttle body and check for proper functioning.
7. Mass Air Flow (MAF) Sensor: A faulty MAF sensor can provide incorrect air flow readings to the engine computer, leading to improper fuel-air mixture and causing the engine to run rough when accelerating. Clean or replace the MAF sensor if necessary.
8. Oxygen Sensor: A bad oxygen sensor can affect the engine's fuel trims and cause it to run lean or rich, resulting in rough running and poor acceleration. Check and replace the oxygen sensor if faulty.
9. EGR System Issues: A faulty exhaust gas recirculation (EGR) system can cause the engine to run rough, especially at higher RPMs. Check the EGR valve for proper functioning and clean or replace it if needed.
10. Fuel Pump Issues: A failing fuel pump may not be able to provide sufficient fuel pressure to the engine, causing it to run lean and rough. Check fuel pressure and replace the fuel pump if necessary.
11. Transmission: Issues with your transmission, such as a slipping clutch, can also cause the engine to run rough when accelerating while idling smoothly.
If you can't identify and fix the problem yourself, it's best to take your car to a qualified mechanic for proper diagnosis and repair.
