mysterious Cyl 4 Misfire between 4500-5200rpm


Mar 4, 2017
South Carolina
2007 BMW 335i (the CPE car)

So here I am trying to finish dialing in these big twins and tuning has gone great through the pump gas revisions, slowly finding parts that need replacing and replacing as we go. Pump tune is good and go to E85 flex fuel map and Cyl 4 has a misfire ONLY at WOT between 4500 and 5200 RPM. Car completely drivable no missfires or anything under normal or even "spirited" driving. Done all the "normal stuff"

So I replaced, Fuel sending unit, LP fuel sensor, Deleted stock FPR, New PR Coil packs and wires, New plugs gapped to .018 (2 step colder NGK) still Cyl 4 misfire on E85 only at just 20-22psi between 4200-5200 rpm without fail. Swapped everything on 4 to Cyl 1 just to make sure. Same results. I have Index 12s with low miles Fuel pressure looks good spark plug doesnt smell like fuel or anything. Engine has 85k miles. What the heck?! I can fill it with 93 pump and do pulls all day runs crazy good no misfires... I have new downstream O2 sensors coming soon but I dont think something isolated to 1 cyl would be fixed by that.

What do you all think? Here are some logs with the misfire in cyl 4.