Transmission Related:
* Transmission problems: This is a very common issue with older minivans. Worn clutches, low transmission fluid, a faulty torque converter, or internal transmission damage can all cause jerking and poor acceleration. A proper transmission fluid and filter change (if applicable to the year) should be considered. A professional transmission inspection is likely needed.
* Transmission solenoids: These control fluid flow within the transmission. A faulty solenoid can cause shifting problems and jerky acceleration.
* Shift cable adjustments: Improper adjustment of the shift cables can lead to inconsistent shifting and poor acceleration.
Engine Related:
* Spark plugs and wires: Worn spark plugs or faulty ignition wires can cause misfires, leading to jerky acceleration and loss of power.
* Fuel system issues: Clogged fuel filter, fuel pump failure, low fuel pressure, or problems with fuel injectors can all restrict fuel delivery, resulting in poor acceleration and jerking.
* Mass Airflow Sensor (MAF) Issues: Even if you replaced a sensor, it's crucial to ensure the correct one was replaced and that it's functioning properly. A faulty MAF sensor provides inaccurate air-fuel mixture readings to the computer, leading to poor performance. Check the MAF sensor connection and ensure it's clean.
* Throttle Position Sensor (TPS): Similar to the MAF sensor, a faulty TPS provides incorrect throttle position information to the computer, leading to poor performance.
* Oxygen Sensor (O2 Sensor): A bad O2 sensor affects the air-fuel mixture, resulting in rough running and poor performance.
* Catalytic converter: A clogged catalytic converter can restrict exhaust flow, causing poor acceleration and potentially jerking.
Other Possibilities:
* Vacuum leaks: Leaks in the vacuum system can disrupt engine performance and cause jerky operation.
* Computer issues: Problems with the PCM (Powertrain Control Module) can affect various aspects of the engine and transmission, leading to jerking and poor acceleration. A diagnostic scan is needed.
Troubleshooting Steps:
1. Diagnostic Scan: The most crucial step is to have a professional mechanic perform a diagnostic scan using an OBD-II scanner. This will identify any trouble codes stored in the PCM that can pinpoint potential problems.
2. Check Transmission Fluid: Check the transmission fluid level and condition. Low, dirty, or burnt fluid is a major red flag.
3. Inspect Spark Plugs and Wires: Visually inspect the spark plugs and wires for wear or damage.
4. Check Fuel Pressure: A mechanic can test the fuel pressure to ensure it's within the proper range.
5. Verify Correct Sensor Replacement: Double-check that the correct sensor was replaced.
6. Check for Vacuum Leaks: Visually inspect vacuum hoses and connections for leaks.
In short: Simply changing a sensor might not solve the problem. You need a professional diagnosis to find the root cause of the jerking and poor acceleration. Ignoring it could lead to more significant and costly damage down the line.
