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.
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.
In general, when we look at Porschedatalogs, we first look at individual cylinder timing correction under full throttle. Timing correction under part throttle would be very normal. Under load though, its okay to see minimal corrections in the cylinders. Example being small corrections in the -1 to -5 range would be normal. Consistent corrections in 3+ cylinders or corrections thatre-incrementwould indicate the mapping is too aggressive for the mechanical condition of the car and or you need higher octane fuel.
Side note for Macans only. Its common for them to be much more aggressive at pulling timing, anything under -6 of timing pull is considered normal. The exception being under heavy load seeing anything over -4 in 3+ cylinders is more concerning. Expect large throttle deltas on initially stabbing the throttle.
Common Mechanical Ailments: - Bad spark plugs/coilpacks - Carbon build up on intake valves on higher mileage direct injection motors - Bad tank of fuel or low octane fuel - Vacuum line detaching from the fuel pressure regulator which is more common on 996 TT, 997.1 Turbos - VTG actuators disconnected at higher mileage common on 997.1 Turbos can occur on other VTG applications. - Charge pipinglooseat compressor outlet, intercoolers, y-pipe, or throttle body. Having a pressurized smoke test done is a great way to quickly diagnose any boost leaks.
With a custom tune, keep in mind that since they're made to specifications other than what we use, normal values may vary. For troubleshooting on a custom map reach out to the Protuner responsible for your tune and they should be able to help you out!
With thousands of cars around the world utilizing these engines, oftentimes swapping a used motor into your car can be a cost-effective alternative to rebuilding a tired or broken engine. However, there are many important things to keep in mind when doing this as not all engines are created equal. Oftentimes engines can come from the exact same model but have different hook-ups, sensors, or manifolds attached to the engine itself. Harder to detect are the engines that have different cam specs or a different compression ratio this means that while getting it to fit can be a simple matter of just swapping a few parts over, getting it to run healthily and correctly is a different matter. Due to the fact that none of the engine's sensors will detect any of these changes, or the potential for a difference in sensor to cause skewed values, you will need to get a custom protuned map when swapping your engine out for anything other than the exact same engine your car had initially with stock specifications. It would be required to have aprotunecompleted if you are going with an engine swap that is not exactly the same as the one you took out.
In the quest for ever more speed and power, eventually, you come to the point of ordering up a built engine block or even having one custom built to your specifications. This is an incredibly exciting day, as you'll no longer be held back by the limitations of the stock bottom end and can explore the upper limits of what your car (and in some cases you) are capable of. Similar to swapping for another stock engine, you'll need to get a custom tune in order to keep your engine running safe and in optimal condition. An added reason for this is that when using aftermarket parts that are forged or billet, there are differences in how much expansion the materials will undergo when they start to absorb the heat of the engine running. As a result, when attempting to run a stock tune with a built engine, you'll probably see a lot of knock numbers from piston noise. It's important to tune the car appropriately for that so that these false knock readings don't mask the ones which are real, just like brakes can help you avoid an accident and keep your car safe, a tune can help avoid detonation or running lean, and keep your new engine safe. It is required to have aprotunecompleted if you are going with a built engine.