Discussing Throttle-by-wire, throttle response, and Pedal Commander 'improvements'
Throttle-by-wire, throttle response, and Pedal Commander
Throttle response is a measure of how quickly a vehicle's engine can increase its power output in response to a driver's request for acceleration. A key factor in this is how fast the Engine Control Unit (ECU) and electronic throttle body open the butterfly valve. Can add-on electronics like Pedal Commander improve throttle response?
In the Ryker throttle-by-wire system (Figure 1), the twist grip sends a Throttle Accelerator Signal (TAS) to the Engine Control Module (ECM, Can Am's term for ECU). The ECM controls a motor in the throttle body that operates the throttle butterfly valve. This setup is often (wrongly) maligned for poor throttle response due to a delay from twist grip action to butterfly opening. This delay can be measured.
The Throttle body sends a Throttle Position Signal (TPS) back to the ECM so that the ECM knows exactly the position of the butterfly valve. By monitoring the TAS and TPS, we can see the relationship between the twist grip position and movement and that of the butterfly valve, the key to throttle response. I did exactly that using an oscilloscope attached to my Ryker Rally 900.
Figure 2 shows the relationship between twist grip and butterfly valve on my Ryker powered on but not running. The blue line is the TAS and the yellow line is the TPS. The TAS varies from .5V at rest to 1.5V fully twisted (.3V twisted back for the start sequence), and the TPS varies from about .5V to 1.8V. (There are actually two TAS and two TPS signals for redundancy, but only one set is needed to make measurements.) To make this measurement, I twisted the grip fast, held it briefly, and then let it snap back to rest. The vertical white dotted lines are measurement cursors, and the delta time is displayed at the lower right corner in orange – 76mS, or less than 1/10 second, to fully twist. This is literally faster than the blink of an eye. The butterfly opens equally as fast, albeit with a small delay.
In Figure 3 I've moved a copy of the TPS over the TAS, and adjusted it to the same scale vertically as the TAS. This allows us to better see the actual delay in butterfly response from twist grip, which is the red area. So there is a delay, but it is less than 50 ms (1/20th second).
Note that when I release the twist grip, it snaps back much faster than I opened it manually – almost instantly. But the butterfly does not close as fast. Why not? The butterfly is operated by an electric motor, which can only spin so fast. The motor also has to overcome inertia in the butterfly valve and the gears that connect the motor to the butterfly valve. Overcoming inertia is why the TPS takes some time to curve upward as the butterfly mechanism goes from zero to maximum speed and downward as it slows back to zero speed fully opened. When up to speed, the maximum rate at which the throttle body butterfly can operate is called the slew rate (shown in orange), and determines the slope of the curve. The Ryker slew rate looks to be about 60mS, which from what I understand is quite good.
If the ECM were limiting throttle response, it would do so by limiting the speed of the butterfly below the maximum throttle body slew rate. We see that normally it does not.
Can Pedal Commander increase butterfly opening speed and consequently throttle response?
Pedal Commander plugs in between the twist grip and the ECM, and alters the TAS. I don't have a Pedal Commander to measure, but fortunately Pedal Commander has charts on their web site that detail operation (Figure 4).
In Figure 5, I copied the Pedal Commander Sport Mode chart and overlaid it with my measurement chart. The dark blue line illustrates what the TAS would look like with Pedal Commander installed. Noting that the initial slope of the Pedal Commander TAS is virtually the same as the slope of the TAS of my twist grip snapping back, we can expect the same TPS response with the same slew rate on opening (although inverted). I superimposed that on the chart in orange. Note that Pedal Commander actually decreases the TAS slope as the twist grip approaches fully twisted, so the actual TPS slope would not be as aggressive as I have illustrated in that area. You can see that there is likely very little difference in TPS (actual butterfly position and speed) with and without Pedal Commander – maybe 20mS or 2/100th of a second. Note also that if I were able to twist just a fraction faster, as fast or faster than the throttle body slew rate, there would be absolutely no difference. (I didn't really pay attention to trying to twist as fast as possible, just fast.)
If I had a Pedal Commander, I'd measure it, but any difference in TPS would be so small as to be negligible.
So, while it is technically true that throttle-by-wire exhibits a delay between grip twist and butterfly, and thus throttle response, the delay is very small. Also, the delay, and the maximum speed at which the butterfly can open, is determined by the characteristics of the throttle body motor speed and the mass of the moving parts. No electronics can make it go faster than the throttle body slew rate. We see that the ECM is not adding any delay in butterfly opening over the physical slew rate of the throttle body, but is operating it as fast as is physically possible. The ECM is not contributing to slow throttle response.
Why do many claim improved throttle response and/or acceleration with Pedal Commander? Because Pedal Commander does make the twist grip more sensitive, a small twist of the grip with it will open the butterfly more and thus deliver more power than the same small twist without it. This increase in sensitivity is perceived as improved throttle response. But we see that full butterfly opening and full power can be delivered as rapidly as the throttle body can operate without Pedal Commander just by twisting more.
The ECU does limit butterfly opening under certain conditions.
I wanted to see what the butterfly was doing under different Ryker modes. These tests were done with the engine running, under real world conditions, with me fully twisting the grip from a standstill.
Figure 6 is Normal mode. You can see that the butterfly initially fully opens, but within a half-second closes considerably as Traction Control takes over.
In Sport Mode, Figure 7, it stays fully open, and the tire spins considerably.
In Eco Mode, Figure 8, note that the butterfly is limited to about 2/3 opening, which is exactly what is stated in the Ryker Operator's Guide. I expected that the ECM would also limit the butterfly slew rate, but it appears not.
In conclusion, throttle-by-wire does not limit throttle response to any appreciable degree. The Ryker ECM normally opens the butterfly valve as fast as is physically possible, in less than the blink of an eye if you twist fast. No add-on electronics can make the butterfly valve open faster.
Last edited by DickB; 12-07-2023 at 05:09 PM.
Reason: Expanded title to briefly state the reason for this thread! ;-)
Thanks for information & description. Not being a speed junkie, I will just say: I am happy if it goes when I want it to and it's Not stalling out & dying!
Last edited by Peter Aawen; 12-08-2023 at 01:34 AM.
Reason: bearing... ;-)
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Thank you for taking the time to share that with us, DickB. Have you happened to take a peek inside the housing at the grip? I am wondering if there's a way to weaken the throttle spring just a bit.
Thank you for taking the time to share that with us, DickB. Have you happened to take a peek inside the housing at the grip? I am wondering if there's a way to weaken the throttle spring just a bit.
Sarah
Hey Sarah. What you might want to try first before you start messing with the spring, and impacting the mechanics of the grip, are the foam grip covers. By making the grip diameter larger, the grip is easier to grab and turn. I use them. One of the first things I put on. Both types fit the Ryker. They are a bit of a science project to put on. There are some videos out there, though.
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Hey Sarah. What you might want to try first before you start messing with the spring, and impacting the mechanics of the grip, are the foam grip covers. By making the grip diameter larger, the grip is easier to grab and turn. I use them. One of the first things I put on. Both types fit the Ryker. They are a bit of a science project to put on. There are some videos out there, though.
I've been using Cinelli handlebar tape for quite awhile, for comfort. Never thought about the twist being quicker. I would assume you could control the diameter of the grip by how much you over lay each wrap. Many colors from Cinelli, but I used black to keep it cleaner looking. Start inward and work outward. Then I used black electrical tape at the opposite end, go a couple times around. It is comfy. https://www.amazon.com/s?k=bar+tape+...ts-doa-p_10_16
Last edited by canamryder; 12-08-2023 at 12:01 PM.
Back on topic: I bought and installed the pedal box on my 2020 RT. I can't explain why, but I can say that trying the box on/off and at all various settings, the output of power from the engine is gained with less throttle twist, and the "red" setting makes throttle input very "touchy". In no way is this a rebuttal to the OP, just relaying my experience to add to the conversation.....
John B.
Current ride: 2020 Spyder RT-s Petrol Metallic Blue dark with OEM top case
Thank you for taking the time to share that with us, DickB. Have you happened to take a peek inside the housing at the grip? I am wondering if there's a way to weaken the throttle spring just a bit.
Sarah
This question has come up in the past ...... I have a 14 RT and removed the spring in the grip to lessen the force needed to turn the grip ..... There is still enough force to return the throttle to " idle " when it's released..... Mike
Throttle-by-wire, throttle response, and Pedal Commander
The Spyder and Ryker have 2 different throttle response curves. Personally, I do not see any reason to put a Commander or Box on the Ryker. It already has a very good throttle response curve. However, all technicalities aside, these devices do make a great deal of difference on the FBW Spyders.
Have you ridden a Spyder with one of these devices installed?
However, all technicalities aside, these devices do make a great deal of difference on the FBW Spyders.
I don't see how.
These devices have been around for decades for automobiles. I tested one, a Sprint Booster, on my 1999 Mercedes SLK. It did not improve butterfly opening speed beyond the throttle body slew rate, which of course it cannot do.
The increase in sensitivity is interpreted by many as an improvement in throttle response. My measurements show that the butterfly opens as fast as is physically possible without a box, just twist fully.
These devices have been around for decades for automobiles. I tested one, a Sprint Booster, on my 1999 Mercedes SLK. It did not improve butterfly opening speed beyond the throttle body slew rate, which of course it cannot do.
The increase in sensitivity is interpreted by many as an improvement in throttle response. My measurements show that the butterfly opens as fast as is physically possible without a box, just twist fully.
Just twisting the throttle fully doesn't get it. You should ride a Spyder with a device installed. I think you'll find that your charts don't give an accurate picture of the end result. The difference is amazing and makes the Spyder much more fun to ride. We have installed quite a few with 100%, very pleased customers. Afterall, you don't ride charts.
Just twisting the throttle fully doesn't get it. You should ride a Spyder with a device installed. I think you'll find that your charts don't give an accurate picture of the end result. The difference is amazing and makes the Spyder much more fun to ride. We have installed quite a few with 100%, very pleased customers. Afterall, you don't ride charts.
Couldn’t agree more, Ron. My Throttle Commander has solved the lag that I was experiencing. Twisting the throttle fully and quickly did not do that, regardless of “in theory” analysis
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Thank you all for the suggestions on the throttle grip solutions, from the simplest to more involved. I'll study a bit more before I do anything. But I'm with Blueknight, the spring is just too stiff for a comfortable grip. I'll let you know what I find if I decide to take a peek inside the housing.
I added foam grips to mine as well. Not only do they provide a larger diameter to grip, which creates a larger torque arm for your wrist. They also dampen some of the vibration.
I did not post "in theory" charts. I posted oscilloscope traces of my Ryker operating in the street, real world, clearly showing that with no external electronics the butterfly is fully opening, rapidly. It can't be made to open faster by any means.
As Ron said, the Ryker and Spyder have different curves and the Ryker dose not a box.
All your tests have been on your Ryker.
a lot of the replies have been from Spyder owners.
Would it be possible for you to run the same tests on a Spyder.
Maybe it will show a different result which would benefit them.
The f3s does open the throttle body 100% you have to snap the throttle open fully it's a little tricky to get right but it does work. All the Pedal Commander does is make it easier to do. All the Pedal Commander does is boost the signal it doesn't do anything that isn't mapped in the ecu and vss already
The f3s does open the throttle body 100% you have to snap the throttle open fully it's a little tricky to get right but it does work. All the Pedal Commander does is make it easier to do. All the Pedal Commander does is boost the signal it doesn't do anything that isn't mapped in the ecu and vss already
If this is true. Why such a huge difference regardless of how you treat the throttle before and after? I put a Pedalbox on my F3 and it has been amazing.
If this is true. Why such a huge difference regardless of how you treat the throttle before and after? I put a Pedalbox on my F3 and it has been amazing.
The logic/science makes perfect sense to me, however, while quick throttle response is important for fast acceleration the CVT is a limiting factor which makes the discussion a little moot for me. A quicker TPS/ECM response can't make up for not being able to drop a cog and dump the clutch.....this will always be a limiting factor for the Rykers in my view. I'm not complaining though, just miss it coming from two wheels :-(
Quote Originally Posted by BajaRon View Post
If this is true. Why such a huge difference regardless of how you treat the throttle before and after? I put a Pedalbox on my F3 and it has been amazing.
If this is true. Why such a huge difference regardless of how you treat the throttle before and after? I put a Pedalbox on my F3 and it has been amazing.
A small twist with Pedal Commander is translated into a large twist. That's all it does, and all it can do. This is interpreted by many as an increase in throttle response. If it makes you happy, cheers.
As Ron said, the Ryker and Spyder have different curves and the Ryker dose not a box.
All your tests have been on your Ryker.
a lot of the replies have been from Spyder owners.
Would it be possible for you to run the same tests on a Spyder.
Maybe it will show a different result which would benefit them.
Yes, of course it would be possible, but I don't have a Spyder. I did have a Mercedes SLK, and did extensive testing on it decades ago with a Sprint Booster. Same result. I don't have to test every throttle-by-wire vehicle on earth to know what the result will be. You say the Ryker and Spyder have "different curves" without any evidence (what is a "different curve" anyway?) When I fully twist the Ryker, the butterfly opens fully, rapidly. When I pushed the SLK pedal to the floor, the butterfly opened fully and rapidly. With and without the Sprint Booster. Why would a Spyder be any different?
If Pedal Commander makes such a difference, I challenge anyone to explain how it does so. I have explained exactly what it does and does not do. Explain to me please anything that I have stated that is not factual.
If the snake oil lives up to its claims and has 100% customer satisfaction, is it still snake oil?
Pedal Commander makes several claims that are not factual.
"The Pedal Commander throttle response controller gives drivers full control of their gas pedal sensitivity."
In Normal mode and Eco mode, butterfly opening is limited by the ECM, so Pedal Commander cannot override this, and give "full control".
"For example, you can press the gas pedal all the way, but the ECM will open only 80%."
True, but only in Eco mode.
"Second, the program decides how fast the throttle body will open. In other words, it doesn’t really matter how fast you are flooring the gas pedal. The ECM controls the speed of the signal so your foot can not make the throttle body faster."
As my data shows, the Ryker ECM does not do this, but rather opens the butterfly as fast as is physically possible.
"By sending the information to the computer this way, a couple of checks that the engine computer will make can be bypassed before sending the signal to open the throttle plate."
This is plainly false, as the ECM is not altered in any way. I asked a Pedal Commander representative several times about how Pedal Commander does this, and got no answer.
"It gives you the response of an "old school" throttle cable, with a 1:1 pedal-to-throttle acceleration ratio."
In any throttle-by-wire system, there is going to be a very small delay as I have explained and shown. Pedal Commander cannot change that. Without Pedal Commander in Sport mode, you do have a 1:1 ratio between twist and butterfly opening. Pedal Commander actually changes the ratio between twist and butterfly opening, as their own charts illustrate. I haven't measured an "old school" throttle cable, but with that system you still must overcome inertia in the system, so I doubt that you could open the butterfly any faster.
Discussing Throttle-by-wire, throttle response, and Pedal Commander 'improvements'
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Originally Posted by greer
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