Logging your vehicle’s performance data is crucial for understanding its health and identifying potential issues, especially for tuned vehicles. This guide provides a step-by-step walkthrough on how to log performance data on an Audi Q7 using the Ross-Tech VCDS (VAGCOM) software and cable, focusing on how to show boost. We’ll cover the setup process, essential parameters for logging, and tips for obtaining accurate results.
Preparing for the Logging Session
Before diving into the logging process, ensure you have the necessary tools and your vehicle is properly prepared.
-
Ross-Tech VCDS Cable and Software: Connect the VCDS cable to your Q7’s OBDII port, located under the dash on the driver’s side. Launch the VCDS software on a Windows-based computer with the car in the “ON” position. Software versions may vary, but parameter names remain consistent.
-
Fault Code Check: Prior to logging, scan for fault codes using the “Auto-Scan” function in VCDS. Address and clear any existing faults to ensure accurate data.
Setting Up VCDS for Logging
Accessing the logging module within VCDS involves navigating through specific menus.
-
Select Engine Module: In the VCDS main menu, click “Select Control Module,” then choose “01-Engine” under the “Common” tab.
-
Advanced Measurement Values: Within the Engine Controller module, click “Adv. Meas. Values” to enter the logging section.
-
Record Ambient Air Pressure: Locate and record the “Ambient Air Pressure” value. This is crucial for calculating boost later, as VCDS doesn’t display boost as an absolute value. Uncheck the box after recording.
Selecting Logging Parameters for Show Boost Q7 VCDS
Choosing the right parameters is essential for effective logging. VCDS limits you to 10 parameters when using grouping, which is vital for accurate time-stamping. Key parameters for showing boost on a Q7 include:
-
For B8/B8.5: Accelerator Position, Charge Air Pressure Specified Value (specified boost + ambient air pressure), Engine Speed (RPM), Air Mass, Intake Air Temperature, Intake Manifold Pressure (actual boost + ambient air pressure), Ignition Angle; Actual, and RFP_AV (bypass valve %). Additionally, consider logging knock detection/correction (IGA_AD_KNK or IGA_AD_1_KNK_x) on at least two cylinders.
-
Saving Parameter List: Save your selected parameters for future use by clicking the VCDS icon and naming the file (e.g., “Performance Log”).
Initiating and Conducting the Log
With your parameters selected, it’s time to start logging.
-
Enable Turbo Mode and Group UDS Requests: Critically, enable “Turbo” mode and check “Group UDS requests” to synchronize timestamps for all logged parameters, ensuring accurate data correlation.
-
Starting the Log: Press “Log,” start the engine, and then press “Start” to begin recording data. Perform a full 3rd (or 4th gear on a dyno or track) pull from approximately 3000 RPM to 7000 RPM.
-
Optimal Logging Conditions: Conduct logging in a safe, controlled environment with minimal traffic, ensuring consistent conditions for accurate comparison. Turn off A/C, radio, ensure windows are up, engage dynamic mode (if available), and disable traction control (ASR).
-
Stopping the Log: Once the log is complete, press “Stop” and then “Done, close.” The log file (.CSV format) will be saved in the Ross-Tech/VCDS/Logs folder.
This guide focuses on Show Boost Q7 Vcds and provides a solid foundation for capturing performance logs. Understanding these logs will help analyze your Q7’s performance and identify potential issues, which will be covered in a subsequent post.
