Quote:
Originally Posted by Compelica
Thanks - but the strange thing is that my actual AFRs and AFR commanded are straying way off from each other... which brought me to my initial tuning question.
As a background I'm on Wayno's tune, only with a decatted OEM header and I'm trying to understand why the actual AFRs are not doing anything to 'catch up' to the commanded. Now @ Wayno himself has stated that the actuals does not need to follow commanded, but to see it run off 0.4 points is unsettling.
The car has also done at least 1000kms since the flash, and I'm seeing a constant LTFT of 2.93 throughout 5500 to redline, so I'm assuming the trims are fine. |
Many points to consider here:
1. It's richer so will be safer and won't cost you any real power.
2. Do you trust the AFR output? Have you verified it?
3. Wayno is correct that the 2 do not need to align. Helpful for mapping but otherwise not actually necessary. It might be that the AFR you have is what is wanted and that the fuel map is setup to achieve that. Not saying that it is, but I know that is a method of tuning.
5. The LTFT is set in buckets, as such, based on load and RPM. This is definable in maps. LTFT is set by the STFT so all the time the STFT is 0, as is the case in open loop, then the LTFT will not adjust. I can't remember where the upper threshold starts but IIRC it's in the mid to low 4k RPM range.
At the end of the day, fuel error and fuel trims are essentially the same. If the STFT and LTFT combined at any given point are +10% then your fuel error is that. If trims aren't active or not set, then you can calculate the error simply by using the input and output AFR. All my log systems use a calculation based on combined fuel trims and pure error, so I can make corrections within seconds of getting data and immediately after flashing.