Hello, new to the site here. First post.
My son and I just completed a DIYer camshaft/lifter/rocker/chain kit replacement on our 2007 F-150 5.4L 3V motor. We purchased the truck used for a grand( yes it was a steal) with a loud engine "TAP" noise. After researching the world wide web, we were confident in our diagnosis of a noisy cam phaser with a secondary timing chain noise. Along with the noises, we had performance issues at speed as well. To our surprise, one of the number 1 intake roller/rockers was seized and damaging the cam.
Back together running fine. My issue is an unused vacuum line that we cant source. The line is not the IWE solenoid lines referred to on a bunch of other posts. It is a 1/4" to 5/16' I.D. line. It tees off of the brake booster with a one way check valve. It clips and routes along the top of the firewall lip and possibly terminates behind the ECM. We must not have been paying too close attention during disassembly. Is this a VENT line? I have seen other posts regarding other vent lines relating to the IWE actuators.
Any clarification is greatly appreciated. We've damn near disassembled the engine compartment looking for a mated boss for this line.


Thanks,
STUMPED

 

Could it be part of the evap purge system?

 

Thanks GLC. most of the diagrams I have seen , show the evap line coming off the intake. My routing sticker is missing off of the truck. I have not been under the hood since my post. Truck runs great. No codes.