From 12+ years of TBI tuning experience, I tend to stay slightly richer than 128 BLM. I stay in the 122-126 range. Would rather let the ECM pull a little fuel than add it. If the BLM is greater than 128 the ECM uses the last value before it enters Power Enrichment and multiplies the fuel value by that percentage. So if it is running 134 BLM at light throttle, when you stand on it the ECM will add 7% fuel across the board. If you are targeting 12.6:1 air/fuel ratio and VE/Fueling is accurate at WOT you will suddenly see the WOT afr in the 11.7 range. If you stay a little on the rich side the engine will respond more smoothly and generally run better all around.
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