Quote:
Originally Posted by number1Tango
from what ive heard not just form this vehicle but other as well, even when you reflash your ecu and get more power, over a given period of time it will start reverting back to how it used to be with the factory AFR. I could be wrong, its just what ive heard.
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That only applies to closed loop AFR changes made with a piggyback. The ECU can and will override any attempts to change the CL AFR from the 14.7:1 target value. Open loop AFR can be modified but is also subject to some ECU changes due to closed loop fuel trim changes. That's why it's so important to zero out your fuel trims before you start tuning.
Quote:
Originally Posted by NoFear99
This thread you are refering me seem very interesting but too complicated for me especially when English is not your language.
May be somebody could explain here what this thread is all about in a simple short summary...
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I'll try to simplify this as much as I can but I'm not sure if it will help.
The ECU sees how much air is entering the engine via the MAF sensor and looks at a preset table to determine how much fuel to add in order to achieve the target AFR. The ECU then reads the O2 sensor to see if the AFR is correct. When the O2 sensor AFR is too lean, the ECU applies a positive short term fuel trim (STFT) to richen the mixture to reach the target value. If, for instance, the ECU always has to add 10% extra fuel at a given set of conditions, it will set a long term fuel trim (LTFT) of +10% which essentially adds 10% to the lookup table value.
Now your tune may start out with a LTFT of 0 and that equates to 13:1 AFR but after some learning time the ECU sets a LTFT of +10%, it will add 10% more fuel making your new AFR ~12:1.
I hope this helps. It's the best I could do in a short time.