Quote:
Originally Posted by GretchenGotGrowl
It always takes some time for things to settle in after you change a tune. You need to drive it a bit and let things like the LTFT settle back in. It may be that after 20-30 miles on the stock tune it would have lost some power.
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Correct. LTFT's CAN carry over into power enrichment (wot mode). The accuracy of the airflow tables like the maf and vve are very important to make sure you arent carrying over any or as little ltfts as possible.
Think of it like this, you get a dyno tune, afr is perfect. You drive home, ltfts learn and they are say -15%. If you have -15% trims at wot, that means it is taking away 15% of the fuel commanded...yikes.
On my car with a cam that has a lot of overlap and is extremely inefficient at idle and lower speeds, I didnt want false trims jacking my power enrichement up, so I run without them. I use stfts only, and they will not carry over into power enrich. LTFTs are just a learned pattern of what the stfts have done in that fuel trim cell zone over a period of time.