'17 Police Interceptor with incorrect OEM bypass valves

[BradM]

Just an FYI for those who may be running a PI. I discovered that my all original 2017 PI has bypass valves that are used by the single bypass valve Ecoboosts (Navigator, Expedition, F150, Transit Van). The part number is FL3Z-9U465-A. However, the PI's and SHO's call for part number AA5Z-9U465-A. These differ in how the valve seals the exit to the intake side. The FL3Z part seals by protruding into the exit tube while the AA5Z part seals by capping off the exit tube. My theory is that since the FL3Z is designed for a single bypass valve system, the flow around the valve itself looks like it would be better whereas the bypass valves designed for dual systems look like they would impede flow (but there are two of them). I'm guessing there was a parts shortage in 2017 and they had a production exception so they could use the FL3Z parts. I like the sealing design for the AA5Z part because boost pressure actually pushes down on the seal to make it tighter during boost. The FL3Z part looks like it could leak under high boost (it's just a plastic-to-plastic interference fit with no rubber seal). I swapped my PI bypass valves with the ones from my 2015 Explorer Sport just to see what happens next time I data log.