2011 Evo X GSR

[D_Eclipse9916]

I also disconnected the ground to the battery, as i read that the people who had done so swore it ran smoother that why. I figured it couldn't hurt either way so i just did it.

the reason it will run smoother is that by disconnecting the battery you're resetting all the ECU's "learned" parameters. instead of it being started up and the car freaking out because now the airflow is completely different than last time it was running, by disconnecting the battery you are "wiping" its memory and it will automatically learn to accomodate the new intake from the start as it adjusts itself to get back to normal driving algorithms.

this is nothing out of the ordinary for OBDII cars with sophisticated ECU's and high sensor resolution. you should reset the ECU by disconnecting the battery any time you make a change to the engine hardware, tuned or not.

It resets Long Term Fuel trims in the ECU's memory. It actually causes it to run a bit wacky the first few minutes especially as Short Term Fuel trims have to wait to go to Closed Loop Mode to learn Long Term Fuel Trims (LTFT). This is why the farther and farther you mod from stock, the harder it is for the ECU at first to learn as there is a limit how much the Short Trim Fuel Trims (in the dsm ECU it was 12.5% swing) can move, but once stored into LTFT, the STFT can now move the +-12.5% based on the next LTFT adjustments.