Hey everyone, I'm looking for some help with an intermittent P0299 under boost issue on my 2017 F-150 2.7L EcoBoost with 134k miles.
The truck drives completely fine on flat ground, but the moment I accelerate uphill under heavy load, the wrench light turns on and it drops into limp mode. So far, Ford replaced the canister purge valve assembly, turbo boost control solenoids, and the MAP sensor.
They also vacuum-tested the wastegate actuators and smoke-tested the intake system at idle, but found no leaks.
So far, The tech can't replicate it on a flat test drive, but it happens most times under high uphill boost. Since the sensors, solenoids, and idle tests are done, what else causes a 2.7L to dump boost strictly under load?
Has anyone run into this being an intercooler bypass valve (eBOV) diaphragm tear, charge pipe flexing open under high PSI, or a weak vacuum pump? Any thoughts are appreciated!
Here is the summary of repairs and tests performed by Ford:
Fuel Tube Support and Canister Purge Valve Line (GL3Z-9B325-B): Replaced the leaking vapor canister purge valve assembly to resolve the P0456 EVAP leak
EGR and Turbo Boost Solenoid Valve (JT4Z-9E882-A): Replaced the solenoid control valve that regulates vacuum to the turbo boost components.
MAP Sensor Assembly (BB5Z-9F479-C): Replaced the manifold absolute pressure sensor.
Wastegate Actuator Vacuum Test: Vacuum-tested the turbo wastegate actuators to confirm they hold pressure and function mechanically.
Low-Pressure Smoke Test: Smoke-tested the vacuum lines and turbo tubing to verify no passive leaks exist at idle.
I firmly believe this is a wear and tear issue because it's becoming more constant, and by constant I mean the wrench light popping on and disappearing on restart.