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Intro to Datalogging

Whether a stock daily driver or a dedicated track car, keeping track of how your car is running is vital to making sure your car will last without needing expensive repairs.  While monitoring gauges on your car can let you know what is happening with a few parameters at a given moment, it won't be able to give you a full scope of how the car is running.  In order to gain perspective over a wider range of time and parameters, we run a datalog.


Here's a good reference on how you actually create a datalog
How To: Datalog


What is a Datalog?

A Datalog is where the Accessport or another system records a user-specified set of sensor data and/or information which the vehicle's computer is using to run the engine.  This can include things from simple data like coolant temperature, to how often the computer wants the fuel injector to be open during a given engine cycle.


Why Can't I Datalog Everything?

While each generation of ECU has different limitations there is generally a limit to the number of parameters you can select.  In most cases, this is because the ECU needs to process the requests for data and output that information to whatever device is requesting it.  As a result of the more monitors you request, the more work the computer has to do in order to keep up.  On some vehicles, as you approach the limit you won't see any differences until it simply can't log more items.  However on other platforms, you will see the approach to the limit show itself as a slow down in the logging rate, so if you are logging a bunch of different items make sure to keep an eye on the amount of time in between each sample to keep things in perspective. The Porsche platform does pretty well if you would like to log everything off the car. If you decide to log PDK parameters (for PDK enabled Accessports only) you may notice a drastic slow-down in logging speeds, so be mindful of how many monitors you select. 


Things Every Good Datalog Needs

A map with no reference points is never going to help you get from one place to another.  There are a few parameters that do wonders for helping to put other monitors into context, as well as showing your environment and driving style. A good starting point when datalogging is to ensure your logging the default monitors as that will give you all of the core data needed. To ensure your logging the default monitors please click on Gauges, then Setup, then Configure Datalogging, Setup once more, and finally click on Reset to Defaults. If your protuner asks you for any additional monitors those can also be quickly added under the Configure Datalogging setup menu when needed.

  • Accelerator Pedal Position - (Accel Ped. Pos.) (drive by wire cars only)
    • Measures the amount the accelerator pedal is pressed down by the driver.  Does not always equate to the same amount of throttle position and can give us additional information similar to what throttle position offers.

  • Actual Load - (Load)
    • Engine load after all compensations.  The amount of power being given based on what the computer sees going on with the engine.
  • Barometric Pressure (Baro Pressure - (PSI, kPA, kPA)
    • A Measure of Barometric Pressure which is the air pressure at your location caused by multiple factors like temperature and elevation.  Different pressures have an impact on air density which in turn will impact the amount of fuel necessary as well as peak boost and the way in which the turbo spools.  At lower pressures (higher elevation) the turbocharger will have to work harder to achieve the same boost pressures.

  • Engine RPM - (RPM)
    • Engine Revolutions per minute.  This lets us see what speed the engine is moving at.  Additionally, conditions of acceleration, deceleration and maintaining a steady speed will all cause variations in the fueling and ignition timing

  • Throttle Position (TPS Act.)
    • How far open the throttle is open changes airflow to the engine and when combined with the RPM helps to give an indication of the amount of load the vehicle is under.

  • Boost - (Positive Manifold Pressure)
    • The amount of boost (PSI, BAR) the positive manifold pressure sensor detects. This peak number will help give a better understanding of how the turbochargers are performing or if any boost leaks may possibly be present. Low numbers could indicate a leak or boost system issue. 


Quick Reference Guides - Platform specific monitors are broken down into 2 separate guides. They are mostly similar but some of the common monitors are different. 

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