* Transmission Issues: This is the most common cause. Problems in the automatic transmission, including:
* Low transmission fluid: Check the fluid level and condition. Low fluid or burnt fluid indicates a serious problem.
* Worn clutches or bands: Internal transmission components wearing out can cause slippage and inability to handle the load of driving.
* Torque converter problems: A faulty torque converter can fail to properly transfer engine power to the transmission.
* Shifting problems: Issues with the valve body or solenoids can prevent proper gear engagement.
* Engine Problems: While the engine idles fine, it may struggle under load:
* Fuel delivery problems: A clogged fuel filter, weak fuel pump, or problems with the fuel injectors can restrict fuel flow, especially under load.
* Ignition problems: Weak spark plugs, failing ignition coil, or distributor issues (if equipped) can lead to misfires, especially when the engine is working harder.
* Vacuum leaks: Leaks in the vacuum system can disrupt the idle and affect performance under load.
* Clogged catalytic converter: A severely restricted catalytic converter creates excessive back pressure, making it hard for the engine to breathe when under load.
* Other Potential Issues:
* Faulty crankshaft position sensor (CKP sensor): This sensor tells the computer the engine's rotational speed, and a faulty one can cause erratic running, especially under load.
* Mass airflow sensor (MAF sensor): A dirty or failing MAF sensor provides inaccurate air flow readings to the engine computer, leading to poor fuel mixture and performance.
* Throttle Position Sensor (TPS): A faulty TPS can provide incorrect information to the computer about throttle position, affecting fuel delivery.
Troubleshooting Steps:
1. Check transmission fluid: This is the first and easiest thing to do. Check the level and condition of the fluid. If it's low, burnt, or smells burnt, you likely have a transmission problem.
2. Listen for unusual noises: Pay close attention to any unusual noises coming from the transmission when shifting or driving.
3. Check for trouble codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the engine computer. These codes can pinpoint potential problems.
4. Inspect vacuum lines: Look for any cracks or loose connections in the vacuum lines.
5. Test the fuel pressure: If you suspect a fuel delivery problem, testing the fuel pressure is crucial.
Important Note: Without a proper diagnosis, attempting repairs can worsen the situation. If you're not comfortable working on your vehicle, it's best to take it to a qualified mechanic for diagnosis and repair. They have the tools and expertise to properly identify the root cause of the problem.
