Throttle Controllers

You’ve seen the names

• Pedal Commander
• Sprint Booster
• X-Pedal
• Hike IT
• Pedal Monster

You’ve seen the claims

“At low revs, the engine responds at approximately half the time in comparison to before.” – Sprint Booster

“There was a difference to the point that I was jerking and spinning the tires in 1st and 2nd I would not believe it if you told me it doesn’t add horsepower it sure helps it tremendously” – D.T. (verified purchaser review on Pedal Commander’s site)

“The delay time whilst accelerating in 3rd and 4th gear and the engine in the mid-range, is almost zero.” – Sprint Booster

“100% better acceleration from stop and a significant increase in power after 3rd gear. Definitely would purchase again.” -S.C. (verified purchaser review on Pedal Commander’s site)

“Best Vehicle Performance upgrade that will remove the acceleration lag from your gas pedal to let you explore the true limits of your vehicle.” – Sprint Booster

“Best Car and Truck Mod, unleash the hidden power in your vehicle to get instant feedback.” – Sprint Booster

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Seriously, check out this video, it’s awesome! But is it too good to be true?

These throttle controllers are widely popular in pretty much every automotive circle where drive-by-wire gasoline internal combustion engines are commonplace. From agile sports cars to offroad trucks, these things are all the rage.  All the cool kids are doing it, and so should you… Right? Not so fast. These things receive plenty of hate from naysayers as well. Bringing up the topic of throttle controllers in a car group is the equivalent of arguing politics with your drunk uncle at Thanksgiving. One side says it’s world changing, the other side says it’s useless. Any candid “conversation” about this immediately breaks down to a closed-minded arguing and name calling with heels dug in and both sides absolutely positive of their stance. For the purpose of this article, I’ll keep the terminology and concepts as basic as possible, but we will take an objective look at what throttle controllers are, how they function, and some pros and cons. The results may surprise you, but this should help you make an informed decision on if one is right for you.

First, we are going to start with the basics of a 4-stroke internal combustion gasoline engine. This is the base engine design typical for what is found in roughly 92% of vehicles registered in the United States. Fuel contains potential energy. An engine makes power by burning fuel, releasing that energy and converting a part of it into the rotational force that drives the engine. There are 4 basic things an engine needs to run: Air, Fuel, Compression, and Ignition. Gasoline needs air in order to burn and at its most basic level, an engine is just a glorified air pump. The fuel makes the power, but the ratio of air to fuel needs to stay within a certain range. The more air you can pump through the engine, the more fuel you can burn in the engine, and that means more power. This is the principle behind modifying an engine’s intake and exhaust systems in order to flow more air to make more power.

Next, we will take a look at the throttle system. Your “gas pedal” as it is commonly referred to, is actually a throttle pedal. This is how you, the driver, request more power from the engine. When you press the throttle pedal you are not adding gas, you are opening the throttle body valve to let air into the engine. The engine monitors how much you let in and adds the precise amount of fuel needed to create the ideal air and fuel mixture it will burn to produce power. Way back in the olden days of yesteryear, the throttle pedal had a cable running from it to the throttle body valve. The simple mechanical cable connection between the throttle pedal and the throttle body meant the driver had complete and absolute control over the throttle valve. As vehicles became less analog and more advanced, the throttle cable disappeared. Today, your foot no longer directly controls the engine’s throttle body. Instead, your throttle pedal is the way your foot requests power from the engine by telling the ECM, or Engine Control Module, that you’re requesting it. That is the drive-by-wire system that is in just about every modern vehicle. The ECM constantly receives input signals and makes adjustments based on what it sees – intake air temperature, coolant temperature, barometric pressure, transmission fluid temp, knock sensors, misfires, ignition timing, vehicle speed, individual wheel speeds, oxygen sensors, catalyst temperature, oil pressure, fuel pressure, camshaft position, crankshaft position, transmission gear, engine RPM, etc. etc. etc. The ECM is constantly factoring in the streams of data it’s receiving from a ton of different sensors. With drive-by-wire, you request power and the engine control module provides it, in whatever manner it determines best based on the tables and parameters written into the ECM programming.

Now, let’s take a look at the drive-by-wire system itself. The throttle pedal and throttle valve both contain redundant position sensors. The redundant sensors work in the same ways but provide different readings. The readings are cross-referenced against each other 100% of the time as a safety precaution. Still, the basic topology of the system is simple: Throttle Pedal Position —–> ECM —–> Throttle Body Valve.

The pedal movement is an input signal to the ECM and the throttle body movement is an output that is controlled by the ECM. It’s similar to pressing a button on a garage door opener. You are not controlling the door. You’re telling the garage door opener that you’d like the door to move, the opener activates the motor which moves the door. An easy way to prove that you don’t actually have control is trying to close the door while something blocks the obstruction beam. You can press that button all day long, but it’s not going to close the door because you don’t control the door motor, the opener does. You can ask the opener to close the door via a button press, but the system is designed with a safety feature programmed to override your input. Your car does the same thing, and your traction control system is proof of that. If you’re in the snow and your tires are slipping, you can keep the throttle pedal to the floor but the the engine control module will still cut throttle and reduce power. Your foot is not what’s in control.

Any good product provides a solution to a problem. So what is the problem that these throttle controls are trying to fix? Lag. There is a certain amount of throttle lag programmed into the ECM on modern vehicles. It serves various purposes but the major ones are to reduce NVH (Noise, Vibration, Harness) and emissions. If a throttle valve is opened too fast under certain conditions it can actually cause the engine to chug and buck briefly adding NVH to the driving experience and reducing performance. Snapping the throttle immediately closed means the fuel mixture can jump briefly to very rich which causes an incomplete burn and added emissions. With the programming in place, when you “floor it”, the ECM will open the throttle at a slightly delayed rate. The other end of the spectrum is rev hang. You notice this when you press the clutch pedal on a manual transmission vehicle and the engine RPMs just kind of float there for a brief moment while the engine completes a clean burn of the combustion cycles in process before dropping down to idle. In the old days, when you pressed the clutch, the engine RPMs dropped like an anchor. All things considered, throttle lag is a pretty minor irritation and is detectable almost exclusively by enthusiasts. If you view your vehicle as an inanimate method of transportation to get from point A to B, it’s likely you’d never notice or care. But if you’re a gearhead, it can drive you crazy to feel so disconnected from the heart of your machine.

So what is a throttle controller and how does it work? Let’s start with the installation. All of these throttle controllers connect inline at the throttle pedal. Instead of the vehicle’s wiring harness plugging directly into the pedal assembly, the harness now plugs into the throttle controller which in turn plugs into the pedal assembly. The topology now looks like this: Throttle Pedal Position —–> Throttle Controller —–> ECM —–> Throttle Body Valve.

The throttle controller takes the pedal position signal and modifies it to change the request for power that the engine control module sees. The amplified pedal movements are still an input to the ECM and the throttle body movement is still an output performed by the ECM.

You can see in this graph above from Pedal Commanders’ website, in its most aggressive setting, depressing the pedal 10% causes an amplified signal to tell the ECM that you have the pedal depressed 85%. The result is that a small touch of the pedal creates a big request for power.

Let’s walk through all this and tie it together. Both the throttle pedal and throttle body valve have a set range of motion. Regardless of physical size, the position inside that range of motion can be anywhere between 0% to 100%. When either the pedal or the valve is at 100%, it can’t go further. There is no 120% throttle or 150% throttle, in fact, if the ECM saw something like that, it would see that as being an implausible signal and would put the vehicle in “limp mode” and cut power as a safety precaution. The actual movement of the throttle body valve is an output function of the ECM, the ECM is the only thing with the ability to control where and how the throttle valve moves. The lag the driver feels between pressing the throttle pedal and the engine responding is a function of the mapping and tables programmed into the ECU. Amplifying the input signal does not amplify the output function. It is not possible for a pedal position signal, whether amplified by a throttle controller or not, to have any effect on the throttle lag as it is all happening downstream at the ECM, not at the pedal itself.

Now that we have functionality established, let’s move on to a more detailed analysis of what this all means:

• It takes .2 seconds for your foot to fully depress the throttle pedal. If you have a very aggressive setting on your controller that is going to signal for full throttle at 25% of the actual pedal position, you end up with a request for full throttle in 25% of the time that it would typically take. That equates to .15 seconds earlier. A throttle controller cannot reduce the lag, but it will provide a head start in getting the full throttle request in. With one of these devices, the computer will see an input for more throttle, sooner. Let’s equate this back to our garage door example again. The door (throttle valve) is going to open as fast as it’s going open, that is determined by the opener (ECM) powering it, there is nothing you can do with that remote control (throttle pedal) to make the door (throttle valve) physically open faster. However, if you had a long-range remote that worked from further away (throttle controller) you can get the request to open the door (throttle valve) to the opener (ECM) earlier. The result is the door (throttle valve) doesn’t open faster, but it would be open sooner. You’re not removing the lag, but you are offsetting some of it.
• The counterpoint to that would be whatever time you gain on the acceleration, you are going to lose on deceleration. The earlier it sends a signal to open the throttle, the later it sends the signal to close the throttle. Using the same example setting as above, the throttle controller is going to send a full throttle signal as you’re releasing the pedal for the additional .15 seconds it takes you to get back down under 25% of the actual pedal position.
• You get a request for throttle in sooner, but in doing so, you give up fine control over the throttle range. You’re making the pedal operate more like an on/off switch with a lot of dead zone, as opposed to having total control you can finesse throughout the whole range of motion. Imagine trying to avoid spinning the tires in the rain, snow, sand, or mud when your throttle controller is requesting damn near full throttle anytime you touch the pedal. Subtlety goes out the window unless you turn it way down, which further reduces the already small window of potential gain.
• These devices plug in at your pedal for easy installation that is completely reversible and undetectable once removed. And many of these devices offer an anti-theft function that, when activated, will render the pedal useless. That sounds cool but it is a bit of a gimmick. The quick removal process means you can bypass the anti-theft function in a few seconds by simply unplugging the throttle controller, removing its function. This anti-theft feature exists solely for the sake of advertising, to add perceived value.
• There is a measurable gain to be had but it needs some perspective. Continuing with the same example again, what would be a very aggressive setting could shave .15 seconds off a request for full throttle. Accomplishing the same task in ¼ of the time sounds significant, but how long exactly is .15 of a second? Well, it’s roughly half the amount of time it takes you to blink your eyes. In the end, a ¼ of nothing is still nothing, and that’s about the amount of time we’re talking about here. This entire debate revolves around the potential for gains that are arguably irrelevant and unlikely to actually be perceivable. You’re paying hundreds of dollars for a device that effectively presses the throttle pedal harder for you. They do have a pretty good resale value and it is another bullet point to add to your mod list, but you’d be much better off saving the money and putting it towards an ECM software flash that can remove the lag written into the software while adding horsepower and torque, and still improving drivability.
• No matter how minor, there are measurable positives associated with having a throttle controller, but there is only one actual negative worth mentioning. There have been many instances of these controllers triggering throttle faults in the ECM which results in a check engine light and the vehicle losing power as it goes into limp mode. When it happens, this is easily fixed by either clearing the faults or removing the device and then clearing the faults but that requires having the ability to scan the ECM and clear faults. But anything can fail–why should that be considered a negative? The only reason I specify this as a negative is that when there is documented evidence of something causing vehicles to unexpectedly lose power without warning, that would be grounds for the auto manufacturer to issue a safety recall. The manufacturers of these throttle controllers are not going to issue a recall or increase quality standards in response to the minority of users having problems.

Some of you are probably thinking, “What about the video at the beginning? That is clear proof it works as advertised right?” Quite frankly, no. The throttle body valve in your vehicle is controlled by the ECM. The display that the maker of the product put together to show off its functionality does not have an ECM. What if we give them the benefit of the doubt for a moment and say there is in fact an ECM hidden in the back of the display and you just can’t see it. If that were the case the moment you disconnect the pedal with the power on, it would trigger position faults which would disable the throttle body from opening, as a safety feature. Not to mention the lack of every single other input signal on its own would put it in limp mode and prevent the throttle from opening to begin with. The ECM would require extensive modification in order to function in this display. So at this point, one of the 2 following scenarios must be true:

• Scenario 1: They have an ECM controlling the pedal back there that you can’t see. They had custom software written to that ECM to remove any and all functionality except for throttle pedal input and throttle valve control. We’re talking about removing every input signal, output control, the ability to throw faults and go into limp mode, etc. However, they left the throttle control functionality intact and untouched. They didn’t modify the software to remove the lag altogether from the ECM so their controller’s settings would in fact control all of the delay that would now be exclusively in the controller. The result of this extensive ECM modification should be that potential customers get to watch their product fail to perform an impossible task, but their product is so good it can do the impossible… in their advertising.

• Scenario 2: Their trade show display is using an external power supply that is wired in a way that a pedal position directly controls the electric motor (the throttle valve) position. And their product is a variable resistance box that can speed up or slow down the movement of the electric motor by adding or removing resistance via settings. And they would assemble this basic circuit so you can watch their product, in their advertisement, appear to operate in a way that it’s not actually capable of doing.

The obvious answer is scenario 2. There is smoking gun proof that this is nothing more than false advertising and deceptive marketing. Approaching the one minute mark of the video, the presenter has the throttle controller set to its most aggressive setting. “You still have full control, you don’t lose anything” he says as he proceeds to show us that 100% pedal gives 100% throttle, 50% pedal gives you 50% throttle, and so on. Remember the example of an aggressive curve from Pedal Commander’s chart earlier? That chart shows in an aggressive setting 50% pedal position would give you 90% throttle valve position. Their demonstration contradicts how the advertising information says it works. It is physically and electrically impossible for it to operate like that in your vehicle. Factor in that we have already established the throttle valve output cannot be sped up via a signal input, another impossibility we watched in the video, and you can only form the decisive conclusion that the functionality you watched is not credible, factual, or possible.

A throttle controller does not increase horsepower or torque, it cannot reduce the throttle lag programmed into the ECM, and the measurable gains it provides border on irrelevance, and yet people tend to react very positively to these devices. They love their controller, but why? Objective evidence points to a combination of 2 factors. The first and most influential, is feel. How you feel about something can’t be defined by any one specific metric. Why is your favorite color blue? Why does music make you happy? Why do you hate the word “moist”? How does watching the sun set over mountains makes you feel good? You like what you like, you hate what you hate, and you feel what you feel. There is no doubt that your vehicle will FEEL like a whole different animal when the slightest touch of the throttle pedal gives you a huge power surge. You can not deny that. It’s going to feel powerful and exciting. It’s going to feel like it moves with urgency, like it wants to get up an go. This is the device that will make your car feel that way. We’ve already established that any literal gain in performance is negligible at best and unperceivable at worst, but you can’t put a defined value on the intangible feeling you get when your eye/foot/brain coordination gets thrown a curveball. A tiny movement causing a huge result is not what your brain has learned to expect. The second, albeit more minor, factor also happens to be in your head. If you take the proven difference in feel and the proven effects of confirmation bias and placebo, its very likely that some combination of them will hit home with you.

A throttle controller doesn’t really do anything productive, but the odds are that if you try it, you’re probably going to love it anyway.