Running On Empty

Discussion in 'Ford Hybrids' started by GaryG, Jun 2, 2006.

  1. GaryG

    GaryG Well-Known Member

    At my last fill up, I mistakenly grabbed the 93 octane nozzle and dumped 12.5 gallons in my tank. At first, I tried to pump the fuel out when I got home, but could not get a hose to the fuel level. Additives such as ethanol are use to increase octane which screw up the oxygen sensors in the FEH.. This has cause me loses of as much as 15 % in FE. My only alternative was to take the hit and burn the tank off through the engine.

    Today, I started my commute with 40 miles past 0 MILES TO EMPTY and put a can of regular gas in the back to prepare to run out of gas.

    From those posting on running out of gas awhile back, I expected the engine to shut down and a warning light to come on telling me to come to a safe stop. This did not happen, the LOW FUEL message did not change. Also, we were told that you were restricted to something like 22mph in EV to get to a station. This was not true today.

    Here is what happen when I ran out of fuel:

    I got on I-95 and was accelerating, but traffic started to slow from 50mph. I went EV at 40mph with only 20% SoC in the battery. Traffic started to pick back up from 30mph, so I hit the gas to go ICE ON and accelerate with traffic. The ICE would not come on, but I accelerated the fastest I have ever done before to 41mph. At first, I thought the ICE was running and the tach stopped working. I was afraid to exceed 41mph in EV, so I back off to 40mph and drove to the nearest exit (about 3/4 mile) and an additional .2 miles to a parking lot. I turned the key off, and tried to restart. Nothing, the FEH acted like I had it in “D” or something. Tried it a few more times, and it started, but idled like it was running out of gas so I turned the key off right away.

    I was amazed that the FEH continued down I-95 at 41 mph on a drained battery. This means I dropped the low side of the battery to a level I’ve never been to. What happen after I added gas to the tank and started the FEH was very interesting. to say the least. As I started to back out of my space, an older person was having a hard time getting his car out of his space, so I had to sit there for a few minutes. All of a sudden, the ICE started to tach up like it does with over regen while I was waiting (stopped) for this man to get out of my way. Strange, but all I could think of, was too much charge from the small generator was overheating the battery which may have been at it’s limit from the 41mph EV run. As I got going, the battery level did not show on the Nav energy screen yet, so I tried a fake shift to boost it up. No regen was possible for two miles and the battery level started showing about 25% SoC.. The battery continued to be very sensitive for about 5 miles.

  2. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Gary:

    ___Now that was an interesting experience and one I would not have suspected to see either? I think a few of those with insides into the Ford Tech group need to beat the bushes a bit to find out how Ford programmed the FEH to deal with 0 fuel. It sounds like the SoC range and protections were overridden and your limp home provided a full on EV mode the likes that have never been seen before?

    ___That must have been an interesting experience to reach deeper into her 1.7 kWh pack then anyone else has ever had the opportunity to do up to this point in time! To bad you couldn’t use it to that extent under normal ops other then your FEH severely restricting all the std. tips and tricks afterwards … That first 2 or so miles after the ICE was drinking gasoline again must have looked pretty awful on the instantaneous ;)

    ___Make sure you post your experience in the YaHoo - FEH group as I am sure many there may find it as interesting as I did!

    ___Good Luck

  3. zadscmc

    zadscmc Member

    I have not run my FEH out of fuel, however, the amount of miles the computer thinks that there are to empty seem to be off in my FEH. I have never put more than 13 gallons into the car (15 gallon capacity, if I remember), with the computer reading less than 10 MTE.

    Is it just conservative?
  4. GaryG

    GaryG Well-Known Member

    Hey Wayne,

    Yes, I had a grin on my face after that experience. It was hard not to take the FEH above 41mph once I knew what was going on. There is no question the electric motors have the power to push the FEH around strictly on their own. I stepped on the pedal harder when the tach didn’t jump, and she responded quite well from 30 - 41mph! My hat is off to the Ford Engineers for a job well done.

    Wayne, you amaze me with your insight as to where my mileage was during the recharge from that deep discharge. There is no question Ford knew taking that battery below their set limit would kill FE. Now, I’m thinking the time it would take the small generator to charge above their set limits would also not increase FE. It may be for the protection of the pack, but clearly there was not much to gain because of recharge and the FE hit. I didn’t think to change my SG to instant MPG and check out the amount of the hit, but my tank average dropped (.3mpg) like I’ve never seen with 668 miles on it.

    Zadscmc, I had 610 miles on the FEH when it hit 0 Miles To Empty, so I went 58 miles past that point. The least of my MPG was 43, and the most was maybe 47mpg because I was in the middle of a warm up period. So my guess is 45mpg over 58 miles which puts the gas left in the tank at 1.28 gallons at 0 MTE. An estimate of the fuel I added with the can and at the pump was 14.5 gallons. I'm sure if the FEH was sitting on the right angle, I could have added 2 more gallons to the tank as I have in the past. With this information, you can be sure you have at least one gallon of gas at 0 MTE, and at least 28 miles (min, 28mpg) past that point in the worst cases,

    Is it conservative or idiot proof? Your guess is as good as mine.


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