Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

The owner was not happy with the way the engine delivers the power compared to the previous NSX he had.


He feels that the launch is sluggish and kick down (AT) is slow.


However, above certain rpm, suddenly, the power kicks in and feels very fast.


Until he brought his NSX to my place, I got so many emails and phone calls regarding this but the owner’s comment was somewhat not consistent.


Depending on the temperature and the timing of his emails and calls, sometimes the issue was still there but other times, he felt it was fine.


One time, he had to stop in the middle of the street causing traffic jam because he saw blinking yellow ECL.


After re-starting the engine, the ECL was gone and he took the car to Honda but no error code was registered…. Bit strange…


As he asked me to look into this, proposed to first read the error code again and then reset the ECU and disconnect the O2 sensors to force the system into Open loop mode.


There was no error code stored and being as full OBD-2 spec, very unlikely to be misfire related as it is carefully monitored by the specific module inside the engine bay together with the 3pin style IG coil.


While I was checking the TH pedal cable play and the effect of trapped rubber carpet under the TH pedal, I opened the air box and immediately found something strange with the air filter.


It was gray when it should be white or light green.


So, lifted it up and … Wow, it was super dirty …


It seems that the car was regularly serviced by the main dealer but this filter was not replaced for a long time due to its low mileage.


If it was replaced within the last few years, the OEM filter would be the green one by now unless it was using the copied Blue Print product.


As the weather was not great, I couldn’t put the filter against the sunblight to check the condition so used the super bright LED light and place the filter on top directly.

The new one looked like this and when I placed the existing filter, I just laughed.


Almost no light came through even placing the filter on top of the LED light body.


As I was bit curious on why it got so dirty and remembered that the owner installed the intake air scoop at the left side wing inlet.

It looked nice carbon product and installation was very good but not sure about the design of the scoop shape.


As I have never used this product on any of the NSX, can’t comment from the experience but there was no chamber to separate the moisture and dust from the fresh air.


It looked as if anything got inside the side air vent will be delivered to the air filter eventually.



Unless you have modified your cam shaft or using super/turbo charger, etc, there is no power gain on C30A engine by modifying the intake area including the air filter and the air box.


On the dyno, some of the aftermarket products were in fact causing loss of the power.

Although it was not included in the service quote, I can’t release this NSX with the state of this air filter so I have replaced it with the new OEM one.


In fact, it was for the next NSX waiting for the TB/WP/Valve service….


The existing air filter will be kept in the bag for the owner to see…


I’m quite sure there will be more reason for the owner’s comment described at the beginning but definitely this air filter was one of the cause of the issue.