What is Tuning and Why Should I Do it?

What is Tuning and Why Should I Do it?

Aug 9, '21

In this blog post we go over the basics of what a tune is and when it's recommended to tune your car.

What is Tuning?

Tuning or getting a tune is a recalibration of your Engine Control Unit (ECU). The ECU is calibrated from the factory for specific inputs and outputs. When you make changes or upgrades to the engine, a tune is always recommended so the ECU can understand the changes to those inputs and outputs. An example would be when installing larger injectors on the engine, the ECU needs to change how long the injectors pulse (width) and timing (latency) to send the pulse. If there is more air going into the engine, a recalibration is needed for the change in air flow.

Tuning is more than just horsepower gains. Tuning is more about recalibrating the ECU for safety and overall performance. It is critical for optimum performance that the ECU understands the inputs correctly as well as the updated outputs for your specific build, so a tune is generally recommended when any changes are made

When Is A Tune Necessary?

Parts changes/upgrades: If you upgrade parts like a bigger turbo or a bigger fuel pump with our fuel pump hardwire kit you need to let the ECU know that you've changed these settings. When in doubt, consult your trusted local tuner because they should have a good idea of whether the changes you have made are significant enough for a tune.

Engine Swap: If you are putting an engine into another chassis a tune is highly recommended for the engine to run properly. An example of this would be putting a JDM engine and JDM ECU into your USDM car. While the JDM engine and JDM ECU are designed to work together, the JDM ECU is calibrated for the much higher fuel quality in Japan. The JDM ECU can only adjust within a range and the quality of fuel that is available here will create a situation that the ECU just can't adjust for. This is where a recalibration of parameters in the ECU comes into play so that it can adjust for the changes lower quality fuel brings. Another example is putting a Subaru engine into a non Subaru chassis like a Porsche or VW. Although from a basic standpoint the ECU can adjust for the changes the sensors on the engine will see with the engine's new location in the rear of the car it is still wise to recalibrate the ECU for these changes so the range of inputs will be correct.

Dyno Tune vs. Road Tune vs. E-tune

This is a great post that goes into detail about the differences - https://www.hpacademy.com/technical-articles/dyno-vs-road-tuning-vs-e-tune/

We are not tuners, but happen to have a few good friends that are and based on our experience with them here are the notes we have.

Dyno Tune - Ideal method of tuning due to a couple factors but mostly safety and the ability for the tuner to put the car into certain conditions to ensure the best possible result. Another thing to consider is if you have swapped to a DCCD equipped transmission in a car that didn't originally come with it. Many dynos require all 4 wheels to spin at the same rate so without the ability to lock the center diff via a DCCD Controller you may either fry the center diff or cause an error with the dyno itself.

Road Tune - As long as there is a driver handling the process of getting the car into the conditions the tuner wants it can be a reliable method. The real concern is safety due to being on the road.

E-Tune - The can be a good option if there aren't any tuners in your area. The key here is that you'll need to handle getting good information to the tuner yourself. This is a scenario where a datalogging Wideband is an absolute requirement because without it the tuner is blind. The key here is don't expect it to be cheaper because the time the tuner will spend is probably greater to deal with the back and forth than it would be to just have the car in person and on the dyno under their control.

iWire Wiring Kits That Generally Require a Tune When Installed

Speed Density

Hybrid MAF Speed Density

MAP Upgrades

Fuel Pump Controller Hardwire Kits

Wideband Kits

AVCS Wiring Kits

Watch the iWire Tune Day Below

Tags: Subaru Swap