Hey guys! I have an '05 FEH 4X4.. about 45,000 miles.. no NAV.

Normally, on our "Average Fuel Economy" display, it fluctuates between 31.2 and 31.5, occasionally flipping one-tenth down (like on the highway) and one or two tenths up (like in stop-n-go). We reset it when we got this car a few months ago, but haven't reset it since.

Anyways, my wife took the car out of town today for a small drive (about 150 miles) to visit a friend. She was using the cruise control.. which by the way she won't do again as she's not happy with how it affected the economy. Anyways, while climbing a hill she said the RPM's jumped all the way up on the gauge (well in the red.. 7000+) and she could not turn off the cruise, not with the cancel button or the brake pedal, and the vehicle continued to maintain the set speed.

She also verified that the engine noise was quite high (but unable to verify if it really sounded like 7000 rpm or not). Once she started going down hill, the RPM's dropped back down to normal, and she was able to turn the cruise on and off with no problems at all, and the vehicle has driven just fine ever since.

However there is one abnormality still present.. the MPG display has increased dramatically, and is fluctuating crazily (almost like it does right after a reset).

We just now took it down the street to the store and I witnessed it fluctuating between 32MPG and 39MPG. Otherwise the vehicle runs great (actually better than before in my opinion), and it is staying in Electric mode a lot longer.. allowing for a bit more throttle before ICU engagement and climbing hills on electric only that it wouldn't do before.

The ICU still kicks on normally (30MPH at moderate throttle, 40MPH at light throttle).. it just simply seems like the electric has more power than before!

I reset the MPG display so we'll see what happens in a couple days when it stabilizes, and while it would be great to find out that I am actually getting 35+MPG, I have a feeling that simply isn't the case (I'll find out after my next fill up when I calculate the actual MPG).

Keep in mind, no wrench light and no MIL has lit up, and all systems say OK going through the list. Also the cruise could have simply been the behavior of the CVT and perhaps a bit of exaggeration by the wife, but something has definitely changed.

Do you think there is a problem here? Or is this just the result of a simple battery reconditioning?

Thanks!

 

Well, the cruise control sounds partially normal and partially abnormal. Cruise control always tries to maintain the set speed, so on steep inclines the engine will rev very high to maintain the speed (especially higher speeds). Afterall, it is only a 4cyl engine. This is why many people avoid using CC because it kill FE if you let it maintain speed on inclines. As for it not shutting off, that sounds, well, scary. I'd have that looked at.

With regard to the computer FE display, it sounds like something might have simply caused it to reset itself, thus resulting in such drastic fluctuations. Maybe whatever caused the CC to malfunction caused an electrical issue that reset the FE computer.

 

I wasn't there, but in a panic, people have been known to push the wrong button or even wrong foot pedal on occasion. ( myself incl. )

The cruise in my car will take the engine RPM right up to red-line and hold it there.
This is OK for short term, but is a killer to MPG.

I suspect your wife's car went to red line on cruise.
This surprised her. ( Heck, it surprises me too, and it makes quite a bit of noise.)

The only way to go past red line is to press the gas pedal at the same time, and even that should only last a second or two, since the car has a speed limiter which will take over PDQ ( pretty darn quick ).

I would not panic unless you can repeat this yourself during calm, controlled conditions.
Like I said, I wasn't there, but in any scary situation, you get 10 different stories from 10 different eye-witnesses. How you remember things happening when adrenaline is pumping don't always match reality.

Last week, I was 'sure' I was a quarter mile from a tornado. I was more than a little nervous. After the dust settled, and I measured it with my odometer, it was 4.5 miles.
-John

 

Haha.. yeah.. obviously I wasn't there to witness the problem. I'm sure 90% of it is normal CVT operation.

The vehicle didn't speed up and 'take off' on her.. it maintained its speed of 70MPH during the process.. she just panicked when she saw it redlining and then some.

I drove it to work today and scanned it (We have a cheap-o OTC Genisys, but it can communicate with all of the modules)... no codes in any of the modules. The only abnormality I found was the transmission fluid temperature seemed low (88f outside, it was reading 70f after idling a few minutes)... BUT this scanner has a few strange things going on with some cars on the data display, so it's hard to tell if that's accurate or not.

Driving home I tried to recreate the problem by setting the cruise to 70 and climbing a hill. It seemed that once the RPMs hit 4000, it revved up quicker with less change in vehicle speed (almost like a slipping normal transmission), but having some familiarity with how the CVT operates, it's hard to judge if it's normal or not.

Next I turned off the cruise and floored it, just to see what it would do, and the needle spiked all the way up into the red until I let off at 90MPH. It's a bit scary, but I still don't think the PCM would allow it to redline for long enough to cause any engine damage.

We're going to drive it a bit before jumping to conclusions.

By the way, the High Voltage Battery State of Charge was at 56-57% on my data screen on the scanner. Does this sound normal? (I would have expected 70-80% but I just don't know what's normal and what's not)

 

The hybrid battery SOC prefers 53%. The vehicle will normally allow between 40 to about 60% but it becomes more dificult to increase SOC as it exceeds 53%. Ford does not program this battery for higher values because doing so will effect durability. Ford wants the battery to last the lifetime of the vehicle.