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How to make a good datalog ?

Why, how and with which tools to create a complete datalog

Jean-Benoît avatar
Written by Jean-Benoît
Updated over a year ago

The datalog function, also known as datalogging, allows for relevant measurements based on the specific datalogging parameters set by the manufacturer.

What is datalogging?

Datalogging involves collecting real-time data from the ECU (Engine Control Unit).
This data includes key measurements regarding the engine's operation, such as:

  • Turbo pressure

  • Load

  • Acceleration

  • Air/fuel ratio

  • Exhaust gas temperature

  • Intake temperature

  • Ignition timing

  • Short and long-term adaptations

  • Etc.

Why datalog?

Reprogramming a car without datalogging is like cooking with your eyes closed.
Nobody can reprogram an engine without feedback on the modifications made.
The information obtained during datalogging is crucial for fine-tuning the modified file.

Various tools are available for proper logging.

Autotuner is undoubtedly the most comprehensive and user-friendly tool for achieving this under optimal conditions.
However, if you have VCDS, this diagnostic tool also allows for precise measurements on the VAG range and in multi-brand scenarios.

Diagnostic tool providers such as Launch or Autel also integrate these functions into certain models offered in their respective ranges.

How to perform accurate datalogging?

  1. Log in a not too short gear (4th or 5th).

  2. Start from low RPM (e.g., 50 or 60 km/h).

  3. Go full throttle and click START to initiate the log.

    When using Autotuner, the tool selects values for you; with other tools, manual selection may be necessary.

  4. Maintain full throttle throughout the log duration (do not release the accelerator).

  5. Once reaching the rev limiter or gear change (or around 4500 rpm for a diesel), click STOP.

  6. Send the log.

    Log submission can be done directly via the vehicle file in the history of your OLSX account.

If you use Autotuner for logging, you can find more information by clicking on the link below.

How to datalog with AutoTuner | FAQ (autotuner-tool.com)

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