40-Series Vellfire T24A ECU Tuning | Solving the Bogged-Down Feel After Switching From a Sub-Controller (Alphard Also Possible)

This time we performed ECU tuning on a 40-series Vellfire (powered by the T24A engine). It is a vehicle with few precedents, but the same work can be carried out on the Alphard, which is popular as a family car and uses the same engine. We will introduce the job along with real feedback from the customer.

The Vehicle & The Work

The vehicle is a 40-series Vellfire with around 20,000 km on the clock. On the intake side it was already fitted with a Britz intake, and everything else was left stock. In this condition we carried out ECU tuning and, based on the catalog figures, achieved gains of up to +35 ps / +80 Nm.

How Is It Different From a Sub-Controller? The Truth About That “Bogged-Down” Feeling

This customer had previously been running a certain sub-controller. This type of sub-controller basically works by adding boost (boost pressure) to make more power. However, the ECU contains a “torque map,” and unless you rewrite it, no matter how much a sub-controller raises the boost, you simply cannot draw out the engine’s true power.

As a result, during the sub-controller era the car had a driving feel of “a bogged-down kind of acceleration, where the power suddenly comes in later.” Because it only kicks in once the boost builds up, there was inevitably a sense of the response being a beat behind.

On top of that, in this customer’s case, the check engine light (warning lamp) reportedly came on frequently after the sub-controller was fitted. It would often light up especially after pressing the accelerator and then lifting off, and the owner told us it was “really annoying.” With ECU tuning, no such warning lamp appears, so you can drive with peace of mind on that front as well.

For more on the difference between sub-controllers and ECU tuning, we explain it in detail in this article, “The Difference Between Sub-Controllers and ECU Tuning.” Please take a look as well.

With ECU Tuning, It’s Fast “Right From the Start” Even at Low RPM

In this ECU tuning we control the ignition, fueling, boost pressure, and the torque map itself in an integrated way. Because of this, there is none of that “comes in later” feeling you get with a sub-controller—the car accelerates smoothly from the very moment you press the accelerator.

The customer also told us, “It’s become properly fast right from the start, more so than with the sub-controller.” He said that even from low revs below 2,000 rpm, the car naturally builds speed on torque.

Completed Same-Day in 2–3 Hours—No Need to Leave Your Car, So You Can Relax

mbFAST Tuning’s ECU tuning is completed the same day, in roughly 2 to 3 hours. Since there’s no need to leave your vehicle with us for days, even those who use their car as a daily family vehicle can entrust it to us with confidence.

The Alphard uses the same T24A engine, so the same work can be performed on it as well. If you would like to improve the acceleration feel of your Vellfire or Alphard, please feel free to get in touch.