I have an 08 escape Hybrid 2WD. I get about 35 mpg in nice weather. The last 2 times it has gotten below about 16 degrees the engine rpms stay at about 2500 for 40MPH or even 3500 for 60MPH. It sounds like the engine is going to explode. the colder it gets the higher the RPM and the lower the mileage. I drove from KC to St. Louis and only got 20MPG. IT was about 6degrees.

I have had it to the ford dealer and they can't find anything wrong no computer codes, nothing.

IS ANYONE EXPERIENCING SIMILAR PROBLEMS?

 

That's not unheard of, but I'm surprised it happened over such a long drive. In Boston on my < 2 mile commute I would get 23 mpg during the winter. That's the lowest I've ever seen.

You might try blocking part of the radiator.

I definitely see the other symptoms when it's cold. The engine revs high. But the engine always warms up and then starts acting normal again.

-salsbr

 

Yes, your mileage will drop in severe cold weather. Cold air is denser and this induces additional fuel dump at the fuel injectors. I have had a similar experience recently. It was minus 6 F at 7:30am when I arrive at work. It was only plus 6 F at 4:00pm when I was excused from work. My hybrid battery temperature was only 34.6 F via the Scanguage II unit when I started my vehicle up. During the almost 4 mile drive home, I experienced excess noise in the vehicle due to the repeated series of charging and discharging of the hybrid battery pack in an attempt to increase its temperature. This is reflected in the AMP reading of the Scanguage II display as it alternates between low and high numbers even when the SOC readings are in low 40 readings. I do not experience this sensation in the AM because I have an engine block heater with a connection to the hybrid battery heater. My Scanguage TaV reading was only 42.1 F when I arrive at home.

There are other cold weather/winter issues that contribute to a loss of fuel efficiency where your vehicle is a hybrid or not. Grin and bear the short term brutal cold snap.

 

What you are experiencing is pretty much SOP for any FWD or F/awd hybrid. A few years ago Ford was granted a US patent for a technique that is likely used throughout the industry for hybrid vehicles.

Elsewhere on the site you can discover that with low SOC of the hybrid battery the rate of charge can be as high as 27KW, ~40HP, if conditions allow it.

I think you will agree that it would NOT be a good idea to apply 40HP of braking to only the front wheels in the event you are traveling on a low traction surface. The Ford patent actually states a formula wherein the regen braking ability is substantially reduced as the OAT declines to and/or below freezing.

Basically it appears that as the potential for encountering an icy roadbed increases the regen capability decreases. Sort of like not allowing you to downshift to a gear that would incur a level of engine compression braking that would result in inadvertent loss of control.

At the temperatures you have related I have no doubt that regen braking was minimized, perhaps dramatically so, and so what you are seeing is likely pretty much SOP. The ICE must run faster than "normal" in order to make up for the partial/moderate/full loss of regen braking.

The patent:

http://www.freepatentsonline.com/658...hlight=5343970

 

Do not read anything posted by Willard West in this FEH section as he does not own a FEH and continues to post incorrect information.

 

Then you should try -20F when your FEH has been sitting all day at work. I average about 10 mpg when running errands or to/from work in this weather. Also it sounds like there's no muffler when you exceed 2000 rpm when it's this cold. At least it's in the garage at night and the block heater warms the engine to 60F before leaving... especially nice when we had -30, -28 and -27 this week....

OTOH, sure starts nice in this weather.

 

I am in the single digits and teens here for the past several days and my mileage has been about 22. Certainly not what anyone driving a FEH desires but I know it is the weather creating this havoc. I just keep reminding myself that my previous vehicle also dropped and did actually worse than this in previous winters. Spring is not too far off and this remains the best vehicle I have ever owned.

 

I got 20 mpg today with 6 F and a 20 mph head wind driving at 65-70 on Interstate. At least after 4 hours I had EV mode again. Don't see much of that this winter unless I've driven at least an hour. Supposed to get close to +30 this weekend.

 

Danger, nitpicking ahead:

Billyk, I don't think you're quite right if you're saying that vehicle mpg goes down because "Cold air is denser and this induces additional fuel dump at the fuel injectors." As I understand it, yes, cold dense air will be mixed with more fuel to maintain the 14.7:1 stoichiometric ratio, however, this mixture (more fuel and more air) will also increase rpm's for a given throttle position. So, to go a given speed, say 55 mph in cold air, one uses less throttle (puts a smaller volume of denser air into the cylinder) and then squirts in the same amount of gas they'd use to go 55 in warmer air.

The density of the air doesn't force a reduction in mileage in fuel delivery terms, but the cold temperature does. Low temperatures don't atomize or mix fuel with air very well, so the mixtures run rich to ensure that enough fuel vaporizes. In theory, this fuel enrichment or "choke" should go away as the engine warms... based on the temperature of coolant, or the cylinder head, but cold weather mileage is still sucky.

Hmmn, does cold denser air also result in a noticable increase in drag?

-J

 

Jet turbine airplanes have greater efficiency at higher level where the air is less dense, less drag.