Everything you need to know about throttle controllers – free horsepower?

The internet is full of wonderful claims about throttle controllers giving you free power…Here’s everything you need to know about throttle controllers.

In a word, no, a throttle controller does not just hand over free horsepower. This is despite what you may read on social media, and from some of the soapboxing companies with questionable marketing ethics. It does, however, change how your Engine Control Unit (ECU) reads input from your accelerator pedal and the speed at which that throttle input is applied to the engine.


Most controllers have various settings, from a rather sedate ‘economy’ mode to an aggressive ‘sports’ or ‘power’ mode. This lets you dial the controller into the specific task you’re undertaking with your four-wheel drive. There are some on the market, such as the iDrive, that have an ‘automatic’ mode, in which the controller will adjust settings based on how heavy you are on the pedal.

Rusty Idrive

How throttle controllers work

To understand how a throttle controller works, first we need to know how the ECU sees signal input from the accelerator pedal. With modern fly-by-wire accelerator control, a signal voltage is sent from the pedal box transducer to the ECU. The ECU then interprets this signal; more voltage to the ECU from the pedal is read as more throttle input.

The pedal also sends the signal as a ‘ramp-up’ signal, in that, if you quickly push the accelerator to the floor, the pedal won’t send a 100 percent throttle signal straight away. This signal ramps up to 100 percent over a second or two, which takes any ‘jerkiness’ out of the acceleration profile.

An aftermarket throttle controller module plugs in between your pedal and the ECU. It manipulates the signal sent to the ECU. There is no modification to the mapping of the ECU, just the speed and amount of input that the ECU receives from the pedal transducer.

What does this mean for you?

The main difference you will notice from the addition of a throttle controller is that acceleration will happen sooner and more aggressively. Dependant on the controller, it can also make your pedal input range smaller. That is not to say that it is physically quicker, as the signal is sent very near the speed of light regardless; the pedal position is seen by the ECU as 100 percent near instantaneously as opposed to ramping up over time.


For example, as standard, 10 percent pedal input will give 10 per cent throttle signal to the ECU. Add a throttle controller, and depending on the profile set, it may send a message to the ECU of 30 per cent when you’re only at 10 percent throttle input. Plus, it will give the 30 percent signal to the ECU straight away, as opposed to smoothing the ramp-up out over time. From a driver’s perspective, with this ‘power mode’ active, your 4X4 feels a lot quicker and more responsive than it did before adding the controller.

The advantages…

Where the throttle controllers shine, is that should you be towing a heavy load, you’ll get up and moving quicker. This improvement in the acceleration profile is what some have incorrectly mistaken for extra horsepower.

Inversely, should you be out four-wheel driving through some rather bumpy or rutted out tracks, you can dial the controller down, so if you inadvertently mash the accelerator, the input won’t be nearly as aggressive and induce bunny-hopping.

Another excellent use for the ‘economy’ settings is in soft sand; it will let you accelerate without spinning the wheels, so you can stay up on top of the soft stuff, instead of spinning and sinking into it.

The disadvantages…

One of the most significant disadvantages with a throttle controller is, on some models, you effectively lose accelerator pedal travel at the top end. As an example, if you have the controller at maximum power, once you’ve hit 50 percent pedal, your ECU is already reading 100 percent input. Anything above that 50 percent pedal input, is going to make no appreciable difference. There is also the slight inconvenience of having to find a place to mount the control box so you’ve got easy access to it, while still being able to see the display. This usually means drilling holes into your dash or taking your chance with double-sided tape. Some units, however, have Bluetooth connectivity, so the module is hidden behind the dash, and you can control it via your smart device; however, this then makes changing settings on the fly technically illegal.

So, do you need one?

This question could well replace the adage about the length of string. A lot of folks who own them will tell you yes, absolutely, they make such a vast difference in acceleration profiles and control.

Some vehicle manufacturers, however, have cottoned on to the benefits and control that owners want from their four-wheel drives. Many new vehicles come with an economy and power mode button (regardless of being auto or manual), that does virtually the same thing, albeit with just two modes, as opposed to some throttle controllers that have upwards of nine different settings.

What to look for…

The answer to this is a horses for courses answer. Most are around the $300 mark, making it a modest investment for a more responsive engine. Before you rush out to buy one, however, check to see if your vehicle has an ‘economy/power’ button, and see if that makes enough of a difference in different driving conditions

Should you go looking for a controller, make sure you get information on exactly how it works and what settings it features. Ask if you can trial a module and take it for a 10-minute drive around the block to see precisely how it works and how it affects your vehicle; they are that quick to install.

Steer clear of cheap eBay knockoffs; one company selling cheap throttle controllers was accused of sending a 100 percent throttle signal to the ECU regardless of where the pedal was. They were quickly removed from sale and recalled. Safety should always come first for you and your family, so taking the cheap way out on something that has such significant control over your vehicle, is not recommended.

This article orignally appeared in Pat Callinan’s 4×4 Adventures Issue 38.