There's a growing rumor that the last Engine Control Unit program update
has caused the engine to operate more frequently, thus lowering the
miles per gallon. I thought I had lost some miles per gallon to the hot
weather until I heard this. Anyone have any support for this?
Note to Toyota, I bought this vehicle because it looked like a good
technological compromise to achieve higher mileage. You've released the
Hybrid Highlander, the GX400h, and the Hybrid Camry with minuscule
improvements in the mpg versus their gasoline only counterparts. I
think you're missing a significant market if this rumor is true and you
continue releasing vehicles with only minor mileage improvements.
Not sure where you are getting your infomation, but both our cars are fully
updated and they are doing equal or better than the last time they were
serviced. The older of the 2 averaged 58+ mpg on a trip from MA to NC and
Second, it's not only about the MPG's but about greatly reduced emissions
from the hybrid synergy drive as well that makes the hybrid version a
'better' car than the gas-only version.
From another owner who had his service performed about the same time I
did and also had his mpg drop noticeably. That's why I came here, to
see if it was only a small sample or a more widespread occurrence.
After the ECU update, performed in conjunction with my 10K service, I too
thought my mileage had been impacted, possibly because I had read this rumor
in the Yahoo group. I checked my tire pressure to find they had seriously
lowered it (low to mid 30's) in conjunction with the tire rotation. I put
it back to 42/40. Over the next few tanks my mileage was as expected given
the nature of the trips, wind conditions, etc.
I can't honestly attribute my initial and subsequent findings to the ECU
update, tire pressure or paranoia arising out of the rumor but I suspect the
It's a learned ISC. Some owners have reported slightly lower MPG,
while the ECUs "relearn their driving habits" (store some data over
time/mileage, to help the tune the vehicle's future performance) after
the 50P ECU upgrade. But it will return to normal in a little while.
Most owners haven't noticed anything after the upgrades, though.
The bigger culprit is that if you live in a hot climate, and are
running the AC a lot, that energy comes from somewhere... Your engine
will come on more often to help power the AC. Whether you have a
Classic (unlikely, as you can't flash the Classic Prius' ECUs) where
the engine has to run to belt-drive the AC compressor, or if you have a
NHW20 (most likely for you) where the engine will come on whenever the
hybrid battery gets low (most likely from powering the electric AC
Just remember that the the governmental fuel economy tests (such as
done by the EPA) are done in ideal temperatures (usually in the 70sF)
and do not use the heater or AC...
Are you saying the Prius' ECU uses more than atmospheric conditions,
accelerator pedal position, and the state of charge of the traction
battery to determine how to control the engine? Do you have a Toyota
document that explains this?
This is not in regards to any governmental fuel rating. This is in
relation to my personal recorded tank fillings and computer readouts. I
record both and both are down about 5 mpg. I consider that
What Michelle is telling us is that the standard does not use heater or A/C,
and for that reason we can expect those to have an impact on our economy
when we do use them. 5 mpg isn't unusual for A/C when the efficiency is so
high initially. It's a matter of fuel used; using a liter of gasoline out of
a tank of gas shows up less on a 20 mpg vehicle than t does on a 50 mpg
I am not comparing my mpg with the EPA mpg.
I am comparing my mpg with my mpg.
From the day I drove it off the lot I have had my air conditioning on
and set to 75 degrees. So all my comparisons include the loss due to
air conditioning. I was getting about 47 mpg. I am now getting about 42
mpg. The two possible explanations are a weather change (it's been what
I consider hot) or an ECU flash. I am still monitoring my mpg and now
that the weather is back to normal, I am still down about 5 mpg. That's
why I requested the experience of others.
what dealer, what other person at that dealer, check you air and emergency
brake just cause:) could be a good heads up, I run my business on windows
3.1 , never crashed, have never lost data, hate to go backwards but
it's the only direction that work's.
check your tire pressure, the level of the oil, and the emergency brake is
fully disengaged, otherwise i have no other suggestions as i did not have
your experience with our updated cars...
best of luck bro!
How did I get involved in this little flame war? I thought that you
just stalked Mr. Pardee and Ms. Steiner across usenet. (The last time
I was stalked, the police were involved.)
Pretty bad when one cannot even remember who it was that they were
Whomever said that a post had to be useful for the OP? Your post
certainly isn't, so why should any others be? oh, do as I say, not as
I do. At least my post was useful to someone, other than myself. Mr.
Pardee understood the intent of my post, but it was maybe unclear to
the OP, maybe because of cultural differences, or that Mr. Pardee is
used to my writing style from other Prius discussion forums that he
could infer my intent better. <shrug>
Let's see now...the OP was obviously NeoPhyte_Rep. Obviously, I was
replying to Michael then Michelle. Since your reading comprehension
disability questions how you got involved in this little flame war,
unless you are a sock for either of those two nyms, you "got" involved
by posting to a branch of a topic when no one was talking to you.
Pretty bad when one cannot even remember who it was they were replying
to...like you...and then tries to muddy the waters with some inane
attributions issue. Get a hearing aid for those voices in your head.
Hopefully, this is the one and only time I reply to you. :-)
Her name is Michelle, and she posted relevant information in this
thread. Your "no one was talking to you" is pure baloney; this is a
public forum, and anyone can participate.
She posted information about EPA mileage testing in response to a
message by NeoPhyte_Rep; you asked questions about what she posted, and
Michael answered your questions.
You then flamed like an asshole.
For the record, email@example.com (Michelle R. V.) and I are two different
people, and Michael Pardee is yet another person.
And Michelle R. V. is one of the most knowledgeable people about the
Prius and about EPA testing on any of the newsgroups or mailing lists
involving the Prius (and probably other hybrid vehicles as well).
Hopefully, that is the last message you ever post to this newsgroup.
Stop Mad Cowboy Disease: Impeach the son of a Bush.
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