Tweeking computer program possible ?

what do you mean by "better the milage"? Do you mean show higher (inaccurate) milage or actualy improving fuel economy?

 

Maggie..he wants to save GAS..and $$

 

Only Toyota issues firmware updates, and you need a THHT to install them (each ECU has its own 'calibration' as Toyota calls it) to your Prius. Depending on your date of manufacture, you may qualify for an update based on a recent issuing limited campaign. You'll get a letter if you fall under the category.

 

But we already have one tweak, the EV button! It works great for low speed driving.
The only onther one I need is for high speed, something to lock the car in an overdrive mode.

Both overdrive at high speed and EV in low speed are kind of the same: Switches to tell the computer you can live for a while with less power so no need to run the engine, or else no need to rev it up to high rpms.

The EV works great when I bother to use it. It really saves gas most of the time, long as you don't use it for power, like accelerating or climbing hills, too much.

 

As a professional programmer, I can tell you that I believe that the Toyota's programmers are most likely programming the best general strategy they can determine based on more information than is available to us.
Optimizing efficiency/performance would be also be a matter of pride.

That said, there are options they could offer which would allow the drivers to improve their numbers.
For example, they could make setttings available which would optimize performance based on the terrain most generally encountered by the driver and typical driving usage:
Mountain, Hills, Plains
Typical Trip Length >60mi, 40-60mi, 20-40mi, 10-20mi, <10mi.
City% / Highway %

 

wouldn't it be nice if you could order customized fuel economy on your Prius?
Toyota satellite scans the topography of your terrain, checks your most used roads and adjusts the computer to give you the best fuel economy/best perforamance accordingly.

 

I read the Prius has 50,000,000 lines of code--and you want more! Drive slow and use cruise control and you'll get good mileage. As discussed in other threads, EV mode does't result in best economy. Many people refuse to believe this because it's hard to understand. The switch is for convience. And for overdrive--its always in "overdrive"; the engine only operates in one gear--high. There is no variable gearing although, Toyota says the car has an eCVT, they're lying, and for a good reason. How many people know what a planetary gear is? And what Toyota does with it is quite remarkable and hard to understand. Power split device is a better term. Go ask a car salesman to explain how it works-Ha!!!! I recently read that Toyota has 650 patents on the hybrid auto technology. What's left for GM to develop. They're 15 years late. As for customized fuel economy, it already has that. The oxygen sensor provides a signal for feedback control which continuously adjusts air/fuel ratio for optimal combustion.

 

The expensive EPA test procedures makes multiple "version" impractical, since they would each have to be certified.

 

:mellow: Howdy jtmhog

Having a computer backbround, I am somewhat interested in the Prius technology. What was your "source of information" in determining that there are 50,000,000 lines of code in the Prius computers' programming?

Amazing machine, this Prius.!!

 

Customization per typical terrain/trip length/city or highway would probably consist of modification of a small number of parameters which likely already exist plus the user interface changes to enable the user to select the parameter set.
All-in-all a very small change and not necessitating much additional testing.

 

How about we go back to the good ol' days?

Do you remember in the older Toyota's they had a switch for power/normal/economy?

Imagine if we had a button or even screen option like that for Prius!


-iggy

 

Heard on the radio that the amount of hybrids GM is planning on releasing by 2010, Toyota will release by the end of this year.

 

EV button helps mileage a lot, and many besides me use it daily for this purpose.
I gain over 5 mpg on my typical commute from using it, tihis time of year.

The idea of adapting to hills must already be in the code and my car behaves entirely differently when I am in mountains vs flat areas. Even the EV button changes how the car works when I am driving without using it. The code is very smart.

The overdrive is the only thing missing, and the fact that shifting is done by generator instead of gears is irrelevent to the issue. W should be able to adjust the torque and speeds. The car is currently optimized for the excessive acceleration most Americans demand, as well as a higher top speed than anyone can safely drive in it.

 

Overdrive is not very meaningful in a CVT, as is the word "shifting." The effective gear ratio is selected based on the familiar factors of speed, load, battery charge, engine temp, etc. Are you saying you want the engine to lug more when cruising at higher speeds? I expect Toyota has already figured out the optimum engine speed vs. road speed at high speed cruise, considering power, emissions, mileage. I don't see a lot of room for improvement.

 

You must also keep in mind that leaning the car out any more WOULD effect emissions. I added a "Power/Economy" switch to my GVR-4, rewrote the code to automatically lean the car out at VERY light loading (from the standard 14.7:1 stoicomtric to 16.2:1), and although it DOES save gas, and reduce CO2 emissions, it also slightly raises NOx emissions, so its actually illegal. The government chose 14.7:1 because it is a compromise between good CO2 and good NOx emissions.
As others have said, I feel that Toyota has done an admirable job in their code, and I doubt if there's much room for improvement, without affecting drivability or emissions.

 

Every engineering project is a balancing act. Toyota has taken that into consideration. In fact every manufacturer has taken that into consideration. What sets them apart is their skill at determining what things to balance and how they are balanced. It doesn't matter if the Prius is run by 50,000,000 lines of code or 5 lines of code, I'm confident that Toyota engineers have balanced out their production and driveability goals the best way they know how.

I agree with others, the concept of overdrive is kind of pointless in a cvt, and even more so with a vehicle where the cvt is simulated by the activities of 3 combined motive sources in the PSD. I know that on flat highway at the speed limit the engine isn't roaring like my old car, which indicates to me that the PSD and the computer systems are doing their job, placing the ICE in its most efficient RPM for a particular speed and amount of effort necessary to obtain and maintain desired speed.

 

Does anyone have a list of what features are re-programmable on the PRius? For example, I had the dealer reprogram the unlock feature so that it does not "beep" when I unlock the car...I also had the dealer reset the time that the car stays unlocked from 20 seconds to a minute and a half or something like that.

I really want to disable the back up beeping after 5-10 seconds but the dealer said it could not be done.

what have other people done?

 

I think overdrive makes as much sense for a CVT as it does for any other transmission. The overdrive is not for the transmission but for the engine.

So yes I want it to lug when I want it to lug instead of downshifting quite so easily.

The over drive mode is there and visible on the displayed instant mpg, but virtually impossible to use around here for more than 3 seconds. I just ideally want to be able to adjust the torque point the rpm increases, so I can choose the balance of economy vs hp. I expect that feature alone would help me get several more mpg. If you live in a flat area, the overdrive as it is works pretty good and this would not help you.

The compromise Toyota chose is pretty ideal overall, but there is no one setting that fits every kind of terrain. And without a select button Toyota has to set things for power and not economy.

With conventional overdrive, you have to shift out of it to accelerate, or even hold speed on a hill, but when you can tolerate the speed changes from the lack of power it helps a lot with economy.
I expect a Prius would work the same but with the added advantage it could be like the EV button and go out of the mode automaticallly when you really pushed the accelerator.

The problem with the car now is even a tiny rise brings the car out of overdrive, and the hysteresis keeps it out even if it is a very short rise, so it requires lots of effort to get it back in the economy mode.

Another way to look at it is now the car downshifts immediatly when the load increases. Then it stays at the higher rpm till you pretty much release the accelerator and coast, ie re-feather.
I'd like it to lug a bit more and then go back to the overdrive lowest rpm mode more easily when the load decreases.

 

AFIK you have a choice of either having it on, or turning it off completely.