ECU Flash affects MPG?

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.
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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 back.
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.
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I didn't see any change in my fuel economy.

I call them feel-good-hybrids. They are essentially meaningless as far as conservation is concerned. I heard GM as some truly phony hybrids.
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...

Where did you hear that rumor?!
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Carpe Diem wrote:

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.
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To me, "growing rumour" seems to be an overstatement.
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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 latter.
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NeoPhyte_Rep wrote:

Rumor?
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 compressor).
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...
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snipped-for-privacy@kluge.net wrote:

Please expand the acronym ISC.

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 statistically significant.
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wrote:

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 vehicle.
Mike
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Michael Pardee wrote:

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.
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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 sometimes it's the only direction that work's.
wrote:

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I'm not sure what this has to do with the Prius.
--
Mike Rosenberg
<http://macconsult.com/cafepress/ Net Junkie and Mac-themed shirts etc.
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wrote:

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!
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On Fri, 25 Aug 2006 09:29:14 -0700, "Michael Pardee"

As usual, the twit twat twins, Victor/Victoria, uh, Michael/Michelle reply with babble that the OP finds useless. They are the same person?
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snipped-for-privacy@cup.com wrote:

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 stalking.
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>
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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. :-)
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wrote:

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, snipped-for-privacy@kluge.net (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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We can only hope, but don't get your hopes up.
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We can only hope Bill kills himself, but he's not bright enough.
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