Oh, and on the studder/sputter, There's not much you can do about it unless you invest in the hardware and a custom tune. I've yet to find anything other than tuning that can really eliminate it. You can THINK you've cleared it up by making a few changes like spark plugs, stretching the contact springs, reseting the ECU with a battery disconnect or with a scan tool, but when the ECU settles back down into it's "normally" learned trims and behavior the problems returns.
The REAL problem is in the OEM ECU tuning, DBW throttle delays, and rev limit overlaps. The rich/lean/rich transitions as you wind it up and shift gears results in a stumble as it clears up and runs hard again. If you have a WOTbox, AP with FFS, or can shift your car at WOT without lifting it doesn't happen. If you rev it right near the limiter(past 6k), the flywheel momentum will carry it right past the rev limiter by up to several hundred rpms so that when you get back on the gas, the power has been cut by the ECU and it takes a several hundred milliseconds to recover.
The OEM tach is not very accurate, so to see all this happening, you'll need an AP or DH set to max recording rate to capture the data.
The REAL problem is in the OEM ECU tuning, DBW throttle delays, and rev limit overlaps. The rich/lean/rich transitions as you wind it up and shift gears results in a stumble as it clears up and runs hard again. If you have a WOTbox, AP with FFS, or can shift your car at WOT without lifting it doesn't happen. If you rev it right near the limiter(past 6k), the flywheel momentum will carry it right past the rev limiter by up to several hundred rpms so that when you get back on the gas, the power has been cut by the ECU and it takes a several hundred milliseconds to recover.
The OEM tach is not very accurate, so to see all this happening, you'll need an AP or DH set to max recording rate to capture the data.
