Recently, a 2018 NSX was delivered to us for installation of the ScienceofSpeed Liquid Injection System. This NSX has an aftermarket exhaust system along with the JB4 Tuning Box from ScienceofSpeed. During baseline testing, we noticed that power was down.

Using the JB4 Mobile app, we were able to log variables like throttle angle and found the factory ECU was closing the electronic throttles by up to 25-30% even at factory boost levels. This was very strange considering the NSX was being operated essentially in factory form.

 
throttle (orange) being closed up to 25-30% despite throttle pedal (red) at 100%

We did notice that the NSX had Michelin PS4 tires installed on the factory wheels in factory sizes. Previously, we had an issue after installing the same tires on another customer's NSX. After the tires were installed with a standard match balance, a slight vibration could be felt at certain speeds. After speaking to the tire manufacturer, the recommended Road Force tire balance was performed, and the vibration issue was resolved.

Road Force tire balancing better simulates the tire on the road for more effective balancing. More details can be found here.

In a prior conversation with a Honda engineer at the Performance Manufacturing Center, the dedicated NSX factory, we were told that the chassis stability module on the NSX is sensitive to tire and wheel balancing. We were wondering if this torque reduction from the factory ECU was caused by the tires.

After a Road Force balance was performed, the issue was immediately resolved, and the factory ECU maintained full throttle angle throughout the rev range on both the street and on the chassis dyno. The power difference accounted for more than 50 wheel horsepower as shown in the graph above.

once tire balancing was performed, engine control unit is maintaining full throttle to rev limiter
 

This experience reiterates how complex the second generation NSX is - especially in the integration of the powertrain and chassis electronic control modules. These interrelationships are largely undocumented and have been able to be better understood by ScienceofSpeed through extensive experience and monitoring of the NSX using our advanced Superflow chassis dynamometer and data logging tools.

When replacing the tires on your NSX, regardless of brand, insist on Road Force balancing for the best result.