Vcds Performance Logging is crucial for understanding your vehicle’s health and identifying potential problems. This guide provides a step-by-step walkthrough on how to perform performance logging using the Ross-Tech VCDS software and cable (formerly VAGCOM). This information is especially valuable for tuned vehicles, allowing you to monitor key performance indicators.
Preparing for VCDS Logging
Before diving into logging, ensure you have the necessary tools: a Ross-Tech VCDS cable and the compatible Windows software installed on your computer. The car can be either in the ON position or running for the initial setup steps.
Checking for Fault Codes:
Prior to logging, it’s essential to check for any existing fault codes.
- Initiate an Auto-Scan in VCDS.
- Start the scan and allow it to complete. This process scans all modules and may take a few minutes.
- If faults are present, save the scan results and then clear them using the “Clear all DTC’s” button. Return to the main menu after clearing faults.
Setting up VCDS for Performance Logging
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Select Engine Module: Navigate to “Select Control Module” and choose “Select.” Then, under the “Common” tab, select “01-Engine.”
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Access Advanced Measuring Values: In the Engine Controller module, click “Adv. Meas. Values” to enter the logging section.
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Record Ambient Air Pressure: Select and record the “Ambient Air Pressure” value. This will be used later for boost calculations. Uncheck the box after recording.
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Select Logging Parameters: Choose the parameters you want to log. VCDS allows a maximum of 12 parameters without grouping, or 10 with grouping (recommended for accurate logs). Fewer parameters result in higher resolution logs.
Recommended Performance Logging Parameters:
Specific parameters and their corresponding group numbers may vary slightly depending on your VCDS version and vehicle model (B8 or B8.5). Refer to the software for the most accurate information. Key parameters often include:
- Accelerator Position
- Charge Air Pressure (Specified and Actual)
- Engine Speed (RPM)
- Air Mass
- Ignition Angle (Actual)
- Intake Air Temperature
- Intake Manifold Pressure (Absolute)
- Knock Detection/Correction (IGA_AD_KNK or IGA_AD_1_KNK_x)
- Bypass Valve Position (RFP_AV)
- Save Parameter List: Save the selected parameter list for future use by clicking the VCDS icon and naming the file (e.g., “performance”).
Initiating and Performing the VCDS Log
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Enable Turbo Mode and Group UDS Requests: This is crucial for capturing synchronized data. Click the “Turbo” button and check the “Group UDS requests” box.
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Start Logging: With the engine running, press “Log” and then “Start” to begin recording data.
Performing the Logging Run:
- Conduct logging runs in a safe, controlled environment where you can safely accelerate to higher speeds.
- Capture a full 3rd or 4th gear pull (approximately 3000-7000 RPM).
- Turn OFF A/C and radio, ensure windows are UP, engage dynamic mode (if available), and disable traction control/ASR.
- Perform logging runs on a flat surface and under consistent conditions for accurate comparisons.
- Stop Logging: Once the logging run is complete, press “Stop” and then “Done, close.” The log file (CSV format) will be saved in the Ross-Tech/VCDS/Logs folder. You can open this file with spreadsheet software like Excel.
This guide provides the foundation for performing VCDS performance logging. Analyzing the resulting data is the next step in understanding your vehicle’s performance. Understanding how to interpret these logs allows for informed decisions regarding tuning and maintenance.
