WagonR VXL RMp Goes high When Downshifting

You might want to try cleaning your idle air control valve and also check for any vacuum leaks.

It seems like youre describing an issue with your car, specifically a WagonR VXL RMp presumably referring to RPM - revolutions per minute increasing when downshifting. This behavior can be indicative of a few potential problems. Here are some common reasons for such issues:

1. **Throttle Position Sensor TPS Malfunction:**
- The Throttle Position Sensor monitors the position of the throttle and communicates this information to the engine control module ECM. If the TPS malfunctions, it may incorrectly signal the ECM to increase the throttle, leading to a higher RPM when downshifting.

2. **Vacuum Leak:**
- Vacuum leaks can disrupt the air-fuel mixture and cause irregular engine behavior. When downshifting, the sudden change in load might exacerbate the impact of a vacuum leak, leading to higher RPM.

3. **Faulty Idle Air Control Valve IACV:**
- The IACV regulates the amount of air entering the engine at idle. If it malfunctions, it can cause erratic RPM, especially during downshifting.

4. **Transmission Issues:**
- Problems with the transmission, such as a slipping clutch o r issues with the torque converter, can lead to unexpected RPM changes during downshifting.

5. **Engine Control Module ECM o r Electronic Throttle Control ETC Issues:**
- Electronic control systems, including the ECM and ETC, play a crucial role in managing engine performance. If these components are faulty, they may cause irregular RPM behavior.

6. **Fuel System Problems:**
- Issues with the fuel injectors, fuel pump, o r fuel pressure regulator can impact the air-fuel mixture and result in abnormal engine behavior.

To address this issue, its recommended to have the car inspected by a qualified mechanic o r take it to an authorized service center. They can perform diagnostic tests, such as checking for error codes in the engine control system, inspecting sensors, and examining the transmission. Addressing the specific cause of the problem will require identifying the root issue through a combination of diagnostic tools and expertise.

If your vehicle is under warranty, its advisable to contact the manufacturer o r dealership for assistance. Remember that timely diagnosis and repair can prevent further damage and ensure the continued reliability of your vehicle.