Throttle Mapping

Let's talk about throttle-by-wire mapping. Heads up, this is going to be a bit long and a bit technical.

It occurred to us the other day that we answer questions and have conversations several times every day to customers, both in the shop and online, about the importance of proper ignition and fuel mapping and the impact that it has on the overall performance of their motorcycle. Customers rarely inquire about changes made to throttle mapping, and we can only attribute that to the fact that it is often overlooked, or simply not talked about in the large motorcycle tuning community. Obviously not all new motorcycles utilize throttle-by-wire systems, but it is becoming a more and more popular method of throttle control as manufacturers are pushed to meet stricter emissions standards and include newer technologies, such as traction control, in their motorcycles.

Here is a very brief and generalized rundown of how they work. Generally speaking, throttle-by-wire systems in motorcycles remove the mechanical link between your wrist and the throttle plates. Instead, when you roll the throttle on or off you are actually turning a potentiometer (commonly referred to as an accelerator position sensor, or APS) that sends a 0-5v signal to the ECU. The ECU then uses that signal in an increasingly complicated algorithm to determine how much to actually move the throttle plates. A signal is then sent from the ECU to an actuator on the throttle bodies that rotates the throttle plates, and that percentage of throttle plate rotation is measured and verified by a separate Throttle Position Sensor (TPS) through a 0-5v signal that is sent back to the ECU.

Compared to modern throttle mapping, fuel and ignition mapping is a fraction of the difficulty to properly dial in. How the bike responds when you roll onto the throttle is equally, or more important, to the average rider than peak torque and horsepower figures. This throttle response is very subjective and isn't something that can easily be measured or tested on a dyno; road and track testing is required to properly build and customize throttle mapping. Modern ECUs often only reference 1-7 fuel and ignition maps (one for neutral and each gear at the most), but they commonly reference throttle mapping based on gear selection AND rider mode selection. If we use the FZ/MT-10 as an example, between the 3 selectable rider modes and all 7 gear selections (including neutral) there is THIRTY NINE specific throttle maps to customize and tune, and we don't leave a single one of them unchanged from the stock mapping. There is always room for improvement in making each rider mode feel more distinct and specific to the conditions that they're built for!

We don't like to settle for less than perfect, so when a small handful of our customers gave us feedback that their throttle response was more or less unchanged from stock, and still just as twitchy and annoying as it was from the factory, after our custom ECU flash, we were pretty confused at first. After dozens of hours, both on the dyno and on the road, testing dozens of different customer FZ/MT-10's we finally found a couple that were most definitely "off". The TPS and APS sensors are usually a very precise system, measuring voltage at the hundredth of a volt. What we have found is that a small number of these bikes are not coming out of the factory with "properly" synchronized sensors. They only need to be within 0.2v (0.45v-0.65v) each at idle. While they aren't out of specification enough to throw a code and cause the check engine light, we have now confirmed that if one sensor is at one end of the voltage range and the other is at the opposite end, it will cause the throttle still feel twitchy or uneasy as you roll on and off the gas. In layman's terms, the throttle isn't as precisely doing what you, or our mapping, are telling it to do.

The process of recalibrating, or more perfectly synchronizing, these sensors on these Yamahas is above the majority of rider's technical abilities, so we have taken the time to build custom throttle mapping specifically for these problematic bikes. If we, or one of our competitors have flashed your FZ/MT-10 ECU and you still aren't happy with the throttle response then send us an email to 2wheeldynoworks@gmail.com. Our new throttle mapping will certainly make an improvement. If you have NOT had your ECU flashed yet, then you will definitely want to check out our Mail-In ECU Flashing Service at www.2wheeldynoworks.com to unlock your bike's full potential!