2012 EcoBoost - Long term update
In June of 2012 I ordered my truck outfitted the way I wanted and took delivery in August. Per signature it is a 2012 F150 Max Payload. Have really enjoyed the truck. Pros: Electronic steer...
Forum Discussion
theoldwizard1 wrote:AlmostAnOldGuy wrote:
Apparently 2011-2014 rely on vacuum to stay disengaged and have had issues with insufficient vacuum.
Most people don't know it, but all EcoBoost engines have an auxiliary vacuum pump because the engine spends a lot of time on light boost (or, if towing/hauling, a LOT of time on medium/heavy boost). Over the years, Ford has used several different vacuum pumps on EcoBoost engines, some mechanical, so electric.
Vacuum is critical for power brakes (the booster is large enough to hold enough vacuum for at least 2 full stops even after it has been disconnected from the vacuum source.) There should be a vacuum reservoir someplace under the hood that stores vacuum fr other accessories. As a test, you might want to tee into that line and watch a gauge while you drive to see how well it holds vacuum.
While everything that you say is absolutely correct, the IWE system does not use that vacuum reservoir. They have their own check valve to hold their own vacuum. The reason they don't use the reservoir vacuum is that when you engage the 4 wheel drive, a solenoid opens that particular section of the vacuum lines to outside pressure, releasing all vacuum. That loss of vacuum engages the IWE assemblies to the hub, engaging 4wd. If the IWE system was connected to the vacuum reservoir, that release of vacuum would also vent off the vacuum of the reservoir.
