- Aug 28, 2023
- 201
- 794
- 128
So a bit of a funny story... Was called to diagnose a "low power" issue on a Yairs that had the HKS Power Editor installed. Just over a month after install, the car has not only lost the original power gain from the installation of the device, but it has less power than it did stock... 
What a lot of these devices do is fool the ECU into thinking the boost is lower than it is (literally inserted between the ECU and MAP sensor), so the ECU raises the boost to hit the target or aim. The ECU will automatically adjust timing, setting a higher knock correction learned value, and automatically adjust fuel in the STFT and then LTFT surfaces. Up to 20%...ish and the ECU won't set a code for system too lean, etc.
So what happened? Well, being torque-based with a million modeling inputs, the ECU learned itself right back to about 1.6 bar of boost. On top of that, the knock correction learned value was still sitting at what it had learned for 2.0 bar of boost.
Removed the Power Editor and reset the ECU learned values, took the car for a drive, and all is back to where it should be. But I wonder what the elevated EGT from excessive timing retard has done to the bits that get hot...
FWIW, I've seen this happen with "remaps," too. ECU learns itself into a corner and starts doing all kinds of weird things, followed by returning to normal after a reset, followed by the "tooner" turning off things that protect the engine... The window to make things work right on a high compression, direct injected engine is narrow. Pick your poison wisely
What a lot of these devices do is fool the ECU into thinking the boost is lower than it is (literally inserted between the ECU and MAP sensor), so the ECU raises the boost to hit the target or aim. The ECU will automatically adjust timing, setting a higher knock correction learned value, and automatically adjust fuel in the STFT and then LTFT surfaces. Up to 20%...ish and the ECU won't set a code for system too lean, etc.
So what happened? Well, being torque-based with a million modeling inputs, the ECU learned itself right back to about 1.6 bar of boost. On top of that, the knock correction learned value was still sitting at what it had learned for 2.0 bar of boost.
Removed the Power Editor and reset the ECU learned values, took the car for a drive, and all is back to where it should be. But I wonder what the elevated EGT from excessive timing retard has done to the bits that get hot...
FWIW, I've seen this happen with "remaps," too. ECU learns itself into a corner and starts doing all kinds of weird things, followed by returning to normal after a reset, followed by the "tooner" turning off things that protect the engine... The window to make things work right on a high compression, direct injected engine is narrow. Pick your poison wisely
