Vcds Logging is an essential tool for understanding your vehicle’s performance, especially for tuned cars. This guide provides a step-by-step approach to performing basic performance logging using the Ross-Tech VCDS software and cable (formerly VAGCOM). We’ll cover everything from initial setup to selecting the right logging parameters. While other logging methods exist, this guide focuses solely on using the full version of Ross-Tech’s VCDS software and cable with Windows.
Preparing for VCDS Logging
Before diving into logging, ensure you have the necessary equipment: a Ross-Tech VCDS cable and a Windows-based computer. The specific VCDS software version may slightly alter parameter location numbers, but parameter names remain consistent. This guide references versions 12.12.1 and 15.7.1, but newer versions may have updated numbers.
Checking for Fault Codes
Prior to logging, it’s crucial to check for any existing fault codes. Connect the VCDS cable to your car’s OBDII port, turn the ignition on, and launch the VCDS software. Initiate an Auto-Scan and clear any detected faults. This ensures a clean logging session, free from potential error interference.
Setting Up VCDS Logging Parameters
Select the Engine module (01-Engine) under the Common tab in the Select Control Module section. Access the Advanced Measuring Values to begin logging setup. Record the Ambient Air Pressure value for later boost calculations.
Selecting Key Logging Parameters for Performance Analysis
Choose the parameters relevant to your logging session. For general performance logging, consider these essential parameters:
For B8 Models: Focus on groups including Accelerator Position (%), Charge Air Pressure Specified Value (hPa), Engine Speed (RPM), Air Mass (kg/h), Ignition Angle (degrees), Intake Air Temperature (°C), Intake Manifold Pressure (hPa), and Knock Detection (IGA_AD_KNK) for a few cylinders. Also consider RFP_AV for bypass valve %.
For B8.5 Models: Utilize similar groups as the B8, adjusting for the specific group numbers in your VCDS version. Key groups include Accelerator Position (%), Charge Air Pressure Specified Value (hPa), Engine Speed (RPM), Air Mass (kg/h), Ignition Angle (degrees), Intake Air Temperature (°C), Intake Manifold Pressure (hPa), Knock Correction (IGA_AD_1_KNK_x), and RFP_AV for bypass valve %.
Save your selected parameter list for future use, naming it appropriately (e.g., “Performance”). This streamlines future logging sessions.
Initiating and Conducting the VCDS Logging Session
Crucially, enable the “Turbo” button and check the “Group UDS requests” box. This synchronizes timestamps for all logged parameters, ensuring accurate data correlation. With the car running, start the logging process.
Conduct logging runs in a safe, controlled environment, ideally on a dyno or drag strip. Capture a full 3rd or 4th gear pull (approximately 3000-7000 RPM), ensuring consistent conditions for accurate comparisons. Disable unnecessary features like A/C and radio, and engage dynamic mode if available.
Saving and Analyzing the VCDS Log Files
Stop the logging process and save the data. Log files are stored as .CSV files in the Ross-Tech/VCDS/Logs folder, readily opened with spreadsheet software like Excel for analysis. This data provides invaluable insights into your vehicle’s performance.
Additional VCDS Logging Parameters: Misfires, Lambda, Fuel
Beyond basic performance parameters, VCDS allows logging various other data points, such as misfires per cylinder, lambda values, and fuel pressures/trims. These provide deeper insights into specific performance aspects. Select the appropriate parameters based on your diagnostic needs.
Optimizing VCDS Logging Resolution in Newer Versions
Users of newer VCDS versions (e.g., 15.7.4) might encounter low logging resolution. Adjusting the “Blk Int” and “Char Int” parameters in the options menu, as recommended by Ross-Tech, can potentially improve data resolution.
