I'm wondering. My '05 Escape has overdrive that I can turn on or off at the
touch of a button (V6). I've noticed it shifts in and out a lot when
driving around town (I can't feel it, but I can see it on the tach). Do you
think my mileage would be better if I turned it off around town? The
default when you start the car is ON.
The salesman told me was when driving up and down hills and when it's really
curvy turning the OD off does help with engine braking and has more control,
and it does.
Are you sure it's shifting in and out of OD rather then locking and
unlocking the Torque converter? In my experience I can almost always
feel an OD shift but lots of times I can't feel the TC lock/unlock
even though I can see it on the tach.
The tranny seems to make the transition very smoothly, but the tach does
jump up or down about 500 rpm. If I turn off the OD the tranny feels just
as smooth, but I don't see the tach jump up and down. The car also has
better throttle response both on and off.
I believe Ashton has hit it on the head. My '02 Escape is like that; at
times, I can definitely feel it shifting, but for the most part, at in-town
speeds, it's the TC locking and unlocking. Generally speeding up or slowing
down a couple of MPH stops that. Either way, I don't think your mileage is
affected enough to worry about it.
No, shifting takes hardly any fuel. And, when it is in overdrive, it is
using as little fuel as possible. Keeping in OD will save some fuel and
not hurt your truck at all. Except when hilly, leave it in OD.
some conditions with overdrive disabled. Cars with variable valve
timing will generally NOT, because they are "on the cam" from
basically idle to full speed - while vehicles with fixed valve timing
can be "lugged" which hurts the fuel economy.
I KNOW that my PT Cruiser does do better mileage wise if Ikeep it out
of OD in some conditions -with the vehicle loaded. Lightly loaded, no.
Thanks all. I thought about doing some experiments to determine if it does
get better mileage one way or the other, but I would have to drive the exact
same course over and over which would just be a waste of time and gas. I
don't have a normal daily commute. I do live in the mountains, and it's
easy to "feel" that when driving in curvy hilly places the response is much
better with OD off. Since it's an automatic I don't really have the control
I would have with a manual and a switched OD.
The car drives very smoothly but the tach does dance around a lot with the
OD on. You can't feel it, but you can "see" it.
You have the same control - mine is an automatic too.
On mine I have a 1,3, and D position on the shifter. The D is in a
circle - meaning OverDrive. Driving in 3 keaps the 4 speed automatic
from shifting into OverDrive (4th).
On my wife's Mystique it has 1,2, and D, plus a green Overdrive button
- On the Ford I can shidt manually 1-2-3 then turn on OD.
On the PT, to do the same requires starting in 1, bumping the shifter
to 3 then pulling back to 1 for second, bumping to 3 for Drive, and
then to D for Overdrive.
And it is programmed that way by the factory to meet the emissions and
fuel economy requirements dictated by the government - where the tests
are done with unloaded vehicles. - and you cannot change it.
The programming CAN be changed. There are numerous devices on the market
that allow you to do so, and programs associated with them for different
situations such as lower or higher octane fuel, better mileage, more power,
different shifting schemes, etc.
Programmers are available for diesel engines, and for V-8 engines.
I have found none for 6 cyl., and V-6, engines. Wife bought an S-10
with a 4 cylinder engine, all I found for it was a chip....
It made minimal power increase. I bought the chip for $24.95, but doing
further research I found out I could have bought resistor from Radio
Shack and done the same thing for $1.00
This one will work with a variety of vehicles and engines:
A number of Escape (which only comes with a 4 or 6 cylinder gas engine,
discounting the hybrid) owners on www.escape-central.com swear by it. Plus
there are plenty of custom tunes available.
It's just my $.02 but, in the Ford and most others I have
seen, leaving the trans in the default OD position and
letting the PCM make the shifting decisions is usually the
best. Different vehicles have different programming
strategy but, OD is a fuel economy strategy whereas
disabling the OD not only kills the OD but, changes the
shift strategy to more of a performance strategy which may
or may not affect fuel economy favorably. In the default
mode, the trans will normally unlock the torque converter
for a few extra RPM's and a slight increase in power. If
the load remains too high for the OD gear ratio, the PCM
will drop it down a gear or two as required to meet the
power demand. By disabling OD, you lose it's ability to
take advantage of the drive ratio with the converter
unlocked for whatever fuel saving could be saved with that
strategy alone and guarantee there are no savings from the
OD. Unless you are in a situation where the trans is
hunting between OD other "gears" it is usually best to just
let it do it's job. The manufacturers have done much
experimentation in this area in search of maximum fuel
economy ratings and production. One thing you should do
with your indicated driving conditions where the trans
frequently shifts is make sure the trans is regularly
serviced. An add-on fluid cooler - in addition to the
factory cooler - to make sure it does not get ony warmer
than necessary can greatly increase transmission life. The
best thing to do with the OD is sit back and enjoy the ride
unless it starts hunting.
little OT, but is it even a good time to have an F150 IN O/D when
towing? Maybe just flat level highway? Or will it be hunting around
popping in and out too much? Just curious as I'm planning to haul a 6K
lbs camper around...
revs to give you the required power without demanding high torque (low
vacuum, rich mix, retarded timing, etc) and you also want the engine
braking capability that OD does not provide, for maximum combined
Understood...By default it's on. Just have to remember to push the
button on the end on the F150's shift stalk after hooking/and starting
up each time...Then again, I'm sure it won't take much for the truck to
gently "remind" me I forgot once I got up to speed, other than a
mechanical hand extending from the dash and smacking me in the head. :)
Not true in MOST cases. MOST automatics do not have variable shift
strategy - and those that do have (generally) a "mode" button.
And it will start hunting a lot sooner with a load of any sort than
empty. 4 passengers, without luggage, can make the average vehicle
"hunt" a lot below about 110kph. The "fuel economy" programming the
manufacturer has "optimized" for is the test cycle - which does NOT
account for a load.
Nobody wants to believe me, but I posted the figures on a different
newsgroup 2 years ago - with 4 adults and luggage in the PT, in OD,
at 100kph, from Waterloo to Montreal it got under 20mpg.
From Montral to Quebec city, same load, still in OD,at 110kph+ I
squeazed close to 25mpg out of it (Canadian Gallon), and from Quebec
City to Fredericton, same load, shifting out of overdrive, and
manually downshifting (much earlier than automatic wanted to, keeping
RPMs up), through the hills, and averaging closer to 115kph, I
averaged just under 34MPG (Canadian).
It defies accepted common knowlege, but my explanation is I allowed
the engine to "breath" -keeping manifold pressure high (relatively low
load) and running in the more efficient range of RPM.
The 2002 PT cruiser develops Max torque at 4000 RPM and max power at
Overdrive cruise at 100kph is about 2200 RPM.
At Max torque RPM the car would be doing 116MPH, where the CD of
something like .42 would definitely cause a significant hit to gas
mileage, but allowing the engine to pull higher revs under less load
when it is working, and then allowing it to shift into overdrive and
basically coast down hills was an effective strategy for fuel mileage.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.