Monitoring the health of your 68RFE transmission is crucial for ensuring optimal performance and longevity. One effective method involves analyzing Clutch Volume Index (CVI) values through OBDII PIDs (Parameter IDs) using diagnostic tools like AlphaOBD. This article provides a comprehensive guide to understanding Cvi Obdii Pids and how they relate to the condition of your 68RFE transmission.
CVI, or Clutch Volume Index, quantifies the transmission fluid volume required to engage a friction element without activating the accumulator piston. As friction material wears, the necessary fluid volume increases, reflected in a higher CVI. This metric offers valuable insights into clutch wear and potential leaks within the transmission system.
According to transmission expert TransEngineer, CVI is measured in units of 1/64 cubic inches. For instance, a 4C CVI of 42 signifies that 42/64 (or 0.656) cubic inches of fluid are needed to engage the 4C clutch.
Accessing CVI data with AlphaOBD involves connecting to the engine function (MY2013-17), navigating to the Plotted Data tab, and initiating a scan. The relevant PIDs are found in tabs 20 and 21:
- Tab 20: LR Clutch Fill Volume, OD Clutch Fill Volume
- Tab 21: UD Clutch Fill Volume, 2C Clutch Fill Volume, 4C Clutch Fill Volume
Activate these PIDs by double-clicking or right-clicking and selecting “Activate Selected.” A green dot indicates activation. Drive the vehicle, shifting through gears 1-6 multiple times to allow the program to record data.
While the real-time values might display as 0.00, the recorded numbers logged during the drive are crucial. These logged values, usually displayed in red, represent the actual measurements. Note that LR and UD might not always have a recorded red number; in such cases, use the value present in the column.
To obtain the CVI, multiply each recorded value by 64.
By understanding and monitoring CVI OBDII PIDs, you gain valuable insights into the health of your 68RFE transmission, enabling proactive maintenance and preventing potential issues. Comparing your CVI values with the recommended ranges can indicate clutch wear or potential leaks, allowing for timely intervention and ensuring optimal transmission performance.
