Hello. Yes the car gets into Hybrid mode just fine without fail. I haven't had an issue with the hybrid battery as far as I can tell. Not sure if the issue I'm having and the hybrid battery are somehow linked.

 

I took the vehicle to Ford.

As per usual, they don't think anything is wrong with the vehicle and had me come pick it up the next day.

Ford, the only thing more incredible than their vehicles, is how incompetent their service staff are.

 

I don't think they know how to diagnose any further. They are not seeing errors or DTCs in the computers, and they maybe don't understand the powertrain theory, so they can't (or do not know how to) diagnose it any further. They can't see the problem and can't replicate it, so they let it go. I think you are going to need to find someone in the LA area who truly understands Hybrids, the FEH in particular, and can spend the time to really diagnose what is wrong here.

And I'm not much better than the Ford guys, because I think what you are describing is that the system is working "OK" but it is not working optimally, and the theory is quite complex.

The FEH system has a planetary gearset, a traction motor, a generator/traction motor that spins IN REVERSE of the main traction motor, and then the ICE. Then the HV electrical battery, which stores and releases energy. Simple in terms of a block diagram, but: the computer controls all of the electrical and mechanical power flow, in a complex dance, to maximize efficiency and provide a driving experience that is similar to an ordinary ICE vehicle. But to do that, its gets complicated. It sounds like something is unbalanced in your vehicle, not working properly, or the way it used to work, but not ** failing ** in the sense that someone can point to a simple answer and say: "Yup, there's your problem."

Have a look at this PDF. Go out to Page 64 to start with the FEH:

http://john2211.nl/Hybride_links_files/Miller_W04.pdf

Look particularly at the electrical system modeling, state transition diagram and the e-CVT dynamics on Page 73. You can see that this is a complex relationship.

If you were in the Chicagoland area I'd suggest BSG Automotive, but I don't know anyone out west. There has to be someone really good out there. It does sound like something is wrong, you're not imagining it, and you need someone who understands the vehicle well to check it out.

Do you have Forscan? Have you ever used anything like it?

 

Also: Is your car 2 wheel drive or 4 wheel drive? Sorry, above I asked about Forscan and you said you have used it.

Since I have to guess: it sounds like there is some kind of parasitic power loss going on somewhere in the transaxle, which might be causing the noise/hum and also causing the computer to force the ICE engine to produce more power/torque to compensate, hence your higher RPMs on a flat highway at 70, and the lower mileage around town, because the computer is commanding the ICE engine to work harder than usual, burning more gas. This might not result in an error message or DTC, because the computer "thinks" the power demand is coming from the driver or road conditions when in fact it's coming from inside the transaxle. That's about all I've got, sorry I don't have a bigger brain.