Actually the general recommendation from this board is 1.1V at idle, and no more that 4.3V at WOT, both measured with key on engine of after fully warming up, readings taken at the middle of the FIPL wires. The folks at the Diesel Stop agreed on the 1.1V idle, but say you can safely go up to 4.5V at WOT. My personal experience with the 4.5V at WOT is that it makes the part-throttle shifts very high, the thing would wind up to near 2500 before hitting next gear and I'm not even 1/4 throttle at the pedal. When my WOT was at 4.5V my idle was at like 1.35V or so, when I brought the WOT down to 4.3V my idle went down to 1.15V, and I'm pretty happy with it like that, still winds up till 3500rpms when floored, but on light throttle it upshifts at like 1800-2000 or so, much much better than before. Now how you get both 1.1 at idle and 4.5 at WOT is a complete mystery to me, the only way I see for achieving this is setting it at 1.1V idle then messing with the WOT stopper screw on the throttle bracket on the other side till the IP opens enough for the FIPL to read 4.5V - does that seems safe? I mean, is there something that can be damaged by the IP opening "too much"? Hoe does one know what to set the WOT stop screw to?
