Good question! The difference you feel while in different drive modes, regardless of tuned or stock, will boil down really to two different things: 1) throttle translation, and 2) shift schedules/characteristics
Throttle translation is pretty simple. The accelerator pedal has a position sensor that can output a position signal, 0% to 100%. Throttle translation takes in the signal from this pedal position sensor and manipulates the signal to increase or decrease. The output signal, or Accelerator Pedal Position (Translated), is used to determine the amount of Requested Torque - a variable that is pretty far up-stream of the entire airflow and boost control strategy. For reference, there can be, and often is, a significant difference between pedal position and the actual angle of the throttle body.
Here are some examples from a stock 2018 Raptor:
- On a stock tune in 'Normal' drive mode, there is a 1:1 relationship between pedal position and translated pedal position. At 33% actual APP, APP Translated is 33%. At APP Translated of 33%, throttle requested torque at 3000RPM would equate to roughly 215 ft./lbs.
- On a stock tune in 'Sport' drive mode, the relationship between pedal position and translated pedal position is non-linear, and gives a more touchy or sensitive feel. At 33% actual APP, APP Translated is 42%. At APP Translated of 42%, throttle requested torque at 3000RPM will be roughly 310 ft./lbs.
But in both drive modes, 100% APP = 100% APP Translated. At 100% APP Translated at 3000RPM, torque request will be roughly 500 ft./lbs. So, you can see how this change in throttle translation can make the car feel a lot more peppy at low to mid pedal inputs, but still doesn't change the maximum amount of torque requests that the ECU and engine sees.
* These torque values are not to be considered actual measurements of output, and should be considered as rough, semi-arbitrary units that are used to model engine output.
When you flash a tune to your ECU, part of what we're doing is increasing the maximum amount of Requested Torque at 100% pedal position, as well as increasing low and mid-range requested torque to create a smoothly transitioning table, where power request tracks pretty linearly with pedal position input. Of course, there is a lot more that goes on outside of requested torque, such as optimizing safe ignition timing, ideal fueling, ideal cam position, etc. But this Throttle Requested Torque table is a good way to view, from a high level, what the sort of differences would be between how the truck behaves in different drive modes stock and tuned.
A cool feature of the Accessport, our OTS maps, and any Protune created in our AccesstunerPro software is the Dynamic Pedal Control (DPC) system. This allows you to tailor throttle translations to your exact preference, either more sensitive or less sensitive. But, again, a DPC setting of -5 or +10 will still give you the same WOT power. So at low pedal inputs, you could configure your Accessport-flashed map to feel very similar to a stock map, or a lot more sensitive than stock. But at WOT, you're going to feel that extra power no matter what. And all of this DPC adjustment can be done directly from your Accessport, without the need to reflash the car or even turn the engine off.
Shift schedules and shift characteristics also change depending on drive modes. For example, you'll notice that in Normal drive mode at low to mid throttle inputs, the transmission will skip shift 1 to 3, 3 to 5, etc. In Sport mode, skip shift does not occur; instead, the trans. will shift 1-2, 2-3, 3-4, etc. regardless of pedal input. This is because the change in the currently active drive mode has changed which shift schedule tables are being used by the transmission controller (TCM). This is just one example, and there are a LOT of other shift characteristics that are drive mode variable. While you might not be able to shave much time off of your 1/4 mile time with a transmission tune or in different drive modes, a tune can greatly change how the car feels in daily driving. That's why we're so eager to get TCM support out, and that's why it is the Ford team's highest priority.
One good thing to know with our product is that if you buy an Accessport now for ECU tuning, you will have the option to add on TCM support later without having to buy a new device. TCM support will be an additional cost feature, but you will be able to enable that feature by purchasing a license key that can be emailed to you. This is how we've implemented that feature for our ECU+TCM support on the Nissan GTR, Porsche PDK, and Volkswagen DSG platforms, so it is a simple, easy, and ironed-out process.
Best,
Sam@COBB
