Quote:
Originally Posted by Tor
LTFT is set in closed loop. The reason it's not zero is because the MAF scale is "generic" and not scaled specifically for your engine and fuel combination. It doesn't matter much at all though as long as LTFT remains fairly constant.
1) When the car is in closed loop, fueling is continuously adjusted with feedback from the O2 sensor. So whatever trim is applied doesn't matter.
2) In open loop, only one thing matters and that is the actual AFR. That is mainly a combination of your LTFT (set in closed loop) and the MAF scaling above 3.2 volts. Since you can't adjust LTFT directly you are left to adjusting the MAF to give you a sensible AFR.
This is the easy way to go about it as opposed to do a full MAF scaling. The downside is you have to wait for the ECU to learn the trims after flashing the car and between each adjustments.
Doing a full MAF adjustment, you would adjust the lower part of the MAF scale so it will set lower LTFT. It's a hassle and probably won't be worth the trouble and has more potential to mess things up.
LTFT vary anyway and are supposed to do so within reason. So do some logs to check that it remains in the same ballpark with intervals. If you have wild swings (and thus wildly swinging AFR), the might be something wrong with the lower part of the MAF which would require adjustments.
I personally wouldn't be too bothered with is going rich above 7k. Realistically how much time does your engine spend at those rpm? And if anything it might add some protection against knock. It might cost a bit of power but at 7k rpm you are on the way down on the power curve anyway and supposed to shift gear.
Disclaimer:
At least that is how I understand things and am always prepared to be corrected and learn from the more knowledgeable.
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Thank you very much for your input, also recognize the nice shape of my AFR
100% same as yours around the 3 - 4.5k area (before you started correcting it). I won't go leaner above 7k, like you said it's beyond max power anyway and it's indeed a small safety measure