Attention Prius Owners, I believe I have discovered a previously unknown Mechanism of Low MPG.

Mendel Leisk · Jul 15, 2024

Trivia: to convert km/100km to mpg (US gallons), or vice versa, divide either into 235.2. I forget how I arrived at that, but it's just a distillation of the conversion process.

Troy1994 · Jul 17, 2024

Mendel Leisk said: ↑

Trivia: to convert km/100km to mpg (US gallons), or vice versa, divide either into 235.2. I forget how I arrived at that, but it's just a distillation of the conversion process.
Click to expand...

That’s handy, thanks!

Frankusa94 · Aug 24, 2024

wr69 said: ↑

I've had the 12V battery unplugged on several occasions on my 2010/2013. At times, it was unplugged for a week - due to my negligence in not having the correct assortment of parts. I never really noticed the MPG's drop after such events. Anytime you futz with a circuit, which has computers in it, you risk static discharge potentially frying the motherboard of the computer. It would not surprise me if its possible to fry the a Prius ECU with a static shock during such exercise. From experience, I had a bad Main ECU and the car ran fine and didn't throw any codes, but failed to beep when locked/unlocked. Very annoying problem, which I eventually had to solve by process of elimination and trial and error - not much info on the Prius computers floating around on the Internet. The other thing I could envision is maybe 12v battery might be going bad and disconnecting it triggers final failure; and MPG doesn't recover due to bad 12V, but I have no logic to back that up ATM.
Click to expand...

Your post made me realize my 07 Prius no longer chirps when doors are locked…and I am also experiencing 40mpg in city and 50+mpg on drives above 40 mph. I did disconnect my 12v a few months… and ICE immediately kicks on with the very little pedal press. Must be an easy way to restore max ev … has anyone spoke to Toyota about this?

Frankusa94 · Aug 24, 2024

TheLastMojojomo said: ↑

I know the post is alot to take in and very schizoy... you do not want to disconnect the 12v Battery. Disconnecting the 12v Battery is what causes the WEAK EV State... you want to avoid disconnecting the 12v at all costs.

The commuting however may activate the MAX EV State. But it is more complicated than just driving. To trigger the parameter that activates the MAX EV State likely requires multiple other factors besides highway driving... like the HV Batt needs to be between 77-104°F for multiple drive cycles in a row and potentially measuring a certain level of Internal Resistance from the Hybrid Battery as well.

I believe the parameter that triggers the MAX EV State is similar to a Drive Cycle Parameter. The Prius needs to meet certain parameters for multiple drive cycles in a row for the Hybrid Control ECU to engage the MAX EV State. Once the parameters are verified it engages the MAX EV State and stays this way until another 12v disconnect or ECU reset.

I'm making a video on this presently after trying everything over the summer to get my Prius to re-engage the MAX EV State including installing a Project Lithium Battery... I've been stuck in the WEAK EV State for 3 years and 50,000 miles now.

I will explain the MAX and WEAK EV States as best as I can in short concise video form and it will all become much more clear. I technically can't prove them yet as I can't directly show the different behaviors between the MAX and WEAK EV States... but there is plenty of evidence from other posters that point to their existence.

Here is a preliminary test video I made earlier this year to showcase the WEAK EV State:

This video shows the WEAK EV State only. It shows the relationship between Pedal Angle, HV BATTERY SOC, and when the engine kicks on.

For the MAX EV State Pedal Angles would be much higher before the engine kicks on at the same SOC's as the WEAK EV State video above. But I can't show that for comparison because I haven't been able to record data for the MAX EV State.

This was just an initial test video. I will have much more info in the final version and have a well written narrative that makes a good argument for the existence of the MAX and WEAK EV States. This may be laying the ground work for a massive lawsuit against Toyota but that is not my intent.

I am working on the final video now as we speak:

Also user @Darklandscape just to keep you updated.
Click to expand...

You may have not proved it all out yet… but you are onto something that is really happening in my 07 Prius… since 12v battery disconnect a few moths ago. My city mpg is around 38 and above 40 mph… mpg is in low 50s… complete opposite of advertised performance. Gas pedal above 10-15% … kicks ice on… even with a nearly full charge battery…
Love to hear the finds of this theory….
Frank

di0tima · Aug 25, 2024

I am also experiencing this behavior on my prius v — over 50mpg on highway and sub 40 in the city! Would really appreciate a way to reset the low ev mode to high ev!

dolj · Aug 25, 2024

I personally believe the (Gen 2) car configures itself in response to the way it is driven.

If you drive it like a race car, it will configure itself for a sport mode (less economy).

If you drive it using typical eco-driving techniques (especially pulse-and-glide), it will configure itself for economy driving.

This is just my observation, take it for what it is worth.

Frankusa94 · Aug 25, 2024

di0tima said: ↑

I am also experiencing this behavior on my prius v — over 50mpg on highway and sub 40 in the city! Would really appreciate a way to reset the low ev mode to high ev!
Click to expand...

I Believe Prius v has a ev mode button you could use to force maximum ev operation…

dolj · Aug 26, 2024

Frankusa94 said: ↑

I Believe Prius v has an EV mode button you could use to force maximum EV operation…
Click to expand...

That's not how the EV button works. Hybrids are not EVs, they are combustion cars. Using the EV button this way is just robbing Peter to pay Paul.

MAX2 · Aug 26, 2024

Frankusa94 said: ↑

You may have not proved it all out yet… but you are onto something that is really happening in my 07 Prius… since 12v battery disconnect a few moths ago. My city mpg is around 38 and above 40 mph… mpg is in low 50s… complete opposite of advertised performance. Gas pedal above 10-15% … kicks ice on… even with a nearly full charge battery…
Love to hear the finds of this theory….
Frank
Click to expand...

I'll put in a few cents.
You have several topics and messages about problems with the fuel system and engine operation of your car. What does the EV mode have to do with it?
You need to understand the engine operation first.

MAX2 · Aug 26, 2024

dolj said: ↑

I personally believe the (Gen 2) car configures itself in response to the way it is driven.

If you drive it like a race car, it will configure itself for a sport mode (less economy).

If you drive it using typical eco-driving techniques (especially pulse-and-glide), it will configure itself for economy driving.

This is just my observation, take it for what it is worth.
Click to expand...

I agree with your theses.
With an aggressive driving style, fuel consumption for the same distance is higher than with smooth pressing of the gas and brake.

Frankusa94 · Aug 26, 2024

MAX2 said: ↑

I'll put in a few cents.
You have several topics and messages about problems with the fuel system and engine operation of your car. What does the EV mode have to do with it?
You need to understand the engine operation first.
Click to expand...

it doesn’t… I’m trying to solve my highway speed stalling issue on 07 Prius

I also noticed a drop in city mpg since battery post cleaning … 1000 lies ago… “possible stuck in weak ev mode”

Frankusa94 · Aug 26, 2024

MAX2 said: ↑

I agree with your theses.
With an aggressive driving style, fuel consumption for the same distance is higher than with smooth pressing of the gas and brake.
Click to expand...

Frankusa94 · Aug 26, 2024

as little as 15- 20 percent pedal/throttle causes engine to kick on… even with all green bars on battery indicator…. This started when I cleaned battery posts 1000 miles ago… seems like Prius stuck in weak ev mode… I think I am also experiencing that phenomenon…. This is a lesser problem compared to highway stalling issue.

Still searching for answers….

✌️

MAX2 · Aug 26, 2024

Frankusa94 said: ↑

Still searching for answers….
Click to expand...

It's hard to look for a black cat in a black room where there isn't one.

TheLastMojojomo · Aug 28, 2024

I will hopefully have my final video out by the end of this year. I have most of the content I need to make the actual video... I've just delayed making it because I'm distracted by other matters.

Yes this is a very real phenomenon. There is too much evidence in my own experience and other people's posts where they describe the exact same MAX and WEAK EV State Behavior between 2 Prius or Toyota Hybrids that can't be explained by anything else..

My guess is there's a process somewhat similar to Ignition Mapping that occurs for the Hybrid Battery. Ignition mapping is where the engine software tests different Ignition points to learn knock values (engine compression causes causes fuel mixture to preignite).

During prolonged highway driving where the Hybrid Battery can be maintained at roughly 60%... software in the HV ECU does an analysis of the Hybrid Battery based on capacity, resistance, Battery temperature and other factors using methods like columb counting.

Here is my original post describing increased EV Output after multiple commutes in a row (3rd highlight paragraph):

Here is a Gen 3 owner that experienced the same thing (3rd highlighted paragraph)

Both of us drove our vehicles on stop & go drive styles for hours a day due to our jobs. Me in action below:

I'm driving in the exact same spot in the exact same way multiple days in a row on the mail route. You become very sensitized to how the Hybrid System behaves at different States of Charges and the behavior of the Hybrid System delivering mail like this... which is why I'm the 1st person to connect the dots to all of these other posts and really done the leg work to filter out any other possible causes like stages of Hybrid Operation, Hybrid Battery Temp, etc.

Now compare two other posts from a 2020 Rav4 Hybrid and 2005 Gen 2 Prius.

They both describe the same phenomenon of one Hybrid putting out more EV Power than the other despite driving both in the exact same condition.

That's because one Prius/RAV4 has met the necessary condition to verify it's Hybrid System health via software measurements and allow aggressive usage of EV Output during city driving, and the other has not. Toyota has likely programmed some version of this software into all of their Hybrids... and thisactually led to a lawsuit against them in the 2015 timeframe...

The cause of the Low EV Output in this lawsuit was misattributed to a software update... where really the software update just activated the latent WEAK EV State Software due to resetting the HV ECU.

The plaintiffs were right that they were experiencing a loss of EV Power and mpg in city traffic because of the update... but it was an indirect result rather than direct which led to the lawsuit going knowhere as they were looking in the wrong place in the software for the issue. When they brought it to Toyota's attention, the cause was misplaced and Toyota was 100% correct in that the low EV Output/MPG was not caused by the Software Update.

MAX2 · Aug 28, 2024

When the 12V battery is disconnected, several ECUs are disconnected.
The engine ECU resets fuel trim settings and other things.
This is more important than resetting the high-voltage battery ECU (internal resistance of module pairs from 22-23 milliOhm to 19 milliOhm and the SOC value.

di0tima · Oct 17, 2024

di0tima said: ↑

I am also experiencing this behavior on my prius v — over 50mpg on highway and sub 40 in the city! Would really appreciate a way to reset the low ev mode to high ev!
Click to expand...

I went in for a recall and my ride home had some improved gas mileage. Time will tell, but maybe this could point to a method of resetting?

dtgpnw · Nov 29, 2024

I have an '07 that hasn't really demonstrated over 40mpg's over a tank (calculations at the pump) since I've owned it, going to do some tests to see if mine is potentially in this state. my EV battery died and just replaced it with a greentec reman. also noted the lack of chirp when locking/unlocking. seen some posts regarding potential for parameters being held in memory even with battery disconnect etc.
good read in reading the warpstealth thread various states of the ICE/EV system are called out during warm up, which I'll study for awareness when driving., thinking I may not have driving conditions suitable to enter state 4 waiting for a new ODB-II adapter since my old one is lost. once it arrives I'll use the torque pro and provide some realtime charts data for your project. Cheers!

some good reading at the org website techno-fandom
user ~hobbit
the prius stuff is under slash prius.html
specifically under link farm (first link) and then five-stages.txt

Ford Galaxie · Nov 29, 2024

TheLastMojojomo said: ↑

Attention Prius owners,

I believe I have discovered an unknown mechanism of low mpg in the Prius. Gen 2's are 100% effected by this. There is significant evidence it applies to the Gen 3 Prius as well. It may even apply to Gen 4's.

This low mpg mechanism is not complete yet, as my personal Gen 2 Prius has been uncooperative in giving me all the data evidence I need. I only have half! So I will need the help of my fellow Prius owners to help me complete this post by testing their Prii. I have a method for testing this low mpg mechanism, which almost anyone can do, later in the post. The more Prii we can test, the better! This low mpg mechanism can easily cause a 10+ mpg difference in city driving!

Any input and help will be greatly appreciated! At the very least, help blow this post up!

TL/DR: Disconncecting the 12v Battery causes memory loss in the ECU's that negatively effects how EV mode functions by roughly halving it's capabilities. This effects City MPG's by 10+. Hybrid System and Drivetrain behavior at speeds above 42mph remains unchanged.

I call this Halved EV mode the WEAK EV State. In some circumstances the Prius never seems to regain it's full EV capabilities, which I call the MAX EV State. My Prius has been in the WEAK EV State for 1.5 years at this point. I have linked posts of other Prius owners who are stuck in the WEAK EV State on this forum. The point of this post is to prove a new mechanism of low mpg. I'm hoping those who read the whole post and test their Prii will be able to gather the evidence for the MAX EV State and maybe figure out what triggers it. I need YOUR help to complete this low mpg mechanism!

Terminology used in this post:

ECU - Electronic Control Unit

EV - Electric Vehicle

HV Batt - High Voltage Battery

ICE - Internal Combustion Engine

MG1 - Motor Generator 1

MG2 - Motor Generator 2

SOC - State of Charge

So what am I talking about?
I'm talking about what happens when you do a 12v disconnect/discharge. This resets certain ECU settings, and causes low mpg's as a result of the memory loss effecting how the Hybrid System runs.

I know knowledgeable Prius owners will say - "Yes Mojo, we know the computers need to relearn certain parameters after a 12v disconnect. It's normal for a Prius to temporarily get worse mpg's when relearning parameters after an ECU reset."

Yes you're absolutely right and I couldn't agree more. But I have found that for what I believe is the Hybrid Control ECU (also known as the HV ECU), the parameter relearn process is more complicated then people realize. The relearn process seems to be based on a certain commute style that needs to be consistently done multiple days in a row, potentially in combination with some other factor, to initiate the ECU's optimal state to max MPG's. In my experience, It seems that under certain circumstances, the Hybrid Control ECU may NEVER enter its optimal state and permanently reduce mpg's!

What is the difference between a Hybrid Control ECU that is at peak parameters compared to one that isn't?
Let me start by saying total power is not effected. If you floored the gas pedal, the ICE, MG1, and MG2 work together to provide as much power to the wheels as quickly as possible. In either ECU state, flooring it, as well as behavior at speeds above 42 mph will essentially be the same.

The main differentiation occurs with how much pedal travel, acceleration, and distance is allowed in pure EV mode before the ICE spins up at speeds between 0-42mph.

I call these two different states of EV operation the WEAK and MAX EV state. In both EV states, EV mode effectiveness directly correlates with HV Battery SOC.
View attachment 218638

The WEAK EV State Graphic Overview.

Hybrid Control ECU States: WEAK vs MAX
In a WEAK EV state Prius, EV mode capabilities are a fraction of its maximum capabilities. Pure EV mode is still possible with exceedingly light pedal pressure, but you have to accelerate VERY slowly. It makes it very unrealistic to stay in EV mode and drive normally the majority of the time in the city traffic. The Prius refuses to discharge the HV Battery aggressively through pure EV mode in any circumstance, even at a full HV Battery charge. Once the HV Batt SOC drops below the 6th SOC bar, the ICE kicks on almost immediately with any amount of pedal pressure. It becomes impossible to use EV mode by itself unless you're at a slow crawl. City mpgs will barley scrape past 35 when in the WEAK EV state..

In the MAX EV state, you get much more acceleration, speed, distance, and pedal travel in EV mode on a much lower HV Batt SOC. EV mode is able to be used aggressively. Easily clearing a mile or more and are able to keep up with the stop and go traffic, accelerating and decelerating completely normally without the ICE kicking on down to 4 HV SOC bars. In most situations, you get about 2-4x the pedal travel/acceleration in pure EV mode compared to the WEAK EV state. However, once SOC drops below 4 bars in the MAX EV state, that's when EV mode will really begin to struggle in normal city traffic and all bets are off as to pure EV mode operation. In my experience, 4 SOC bars in a MAX EV state Prius is equivalent or greater to 8 SOC bars in a WEAK EV state Prius in terms of EV Mode ability. The MAX EV state roughly doubles EV mode capabilities. That's how drastic the difference is, and why city mpg's are generally effected by 10 or more. In the MAX EV State, you should be getting 45+ mpg's during city driving. The MAX EV State is the half of the mechanism I don't have data for.

Entering the MAX EV State: What triggers it?
What causes the Hybrid Control ECU to enter the MAX state? I couldn't tell you 100% for sure in no uncertain terms, but commute style seems to be the most critical factor. I have a general idea of what seems to be required. It seems that a period of interstate driving at 65+ mph, possibly with cruise control on, done multiple times, with a rest period, done 2-3 times in a row is required to initiate the MAX State. I must stress, I'm not 100% sure on the exacts of the commute style required. There may be other factors as well. Doing this was just the commute style that reverted my ECU back to the MAX EV state after over a year of being in the WEAK EV state. Once my ECU achieved the MAX EV state, it stayed that way no matter how or where I drove until a 12v disconnect.

This is where it starts to get complicated...
I'm not going to go in-depth to it here... but for the whole comprehensive background story to this post, read My Low Mpg Story Post. My occupation as a rural carrier, which requires the use of my Prius, had a lot to do with me figuring all of this out.

But to summarize, my Prius has spent 2 separate long periods of time in the WEAK EV state since I bought it in 2016. I was in the MAX state for the first year or so after acquiring the vehicle. Then I disconnected my 12v battery in late 2017ish and lost EV power and was in the WEAK EV state. This maintained until mid 2019 when I engaged in the commute style above and re-entered the MAX EV state. I disconnected my 12v Battery 2 separate times after this in 2019, which caused my Prius to revert to the WEAK EV state. But as long as I did the commute style above a few consecutive times, my Prius would re-enter the MAX state.. In 2020 I disconnected my 12v Battery again and lost the MAX EV state.

The problem is I haven't been able to get my Prius back into the MAX EV state since my last 12v disconnect in 2020, despite doing similar commutes that triggered the MAX EV state before. There must be another factor I'm missing or something that's different with my Prius now. I believe commute is still a primary trigger regardless. My HV Battery is still at 65% health according to Dr. Prius. I don’t think HV Battery health is a factor in why this occurs as long as it's not failing and seems to be functioning otherwise normally. No other error codes of any kind either. My Prius appears to be in perfect health. Again, read my Low MPG Story Post for the specifics.

To back up these claims...
I've found several other posts on PriusChat/Reddit that describe this exact low mpg phenomenon of the ICE spinning up quickly with little pedal travel.

First, here is a different post I made a few months ago on PriusChat describing what I described here, just not as fleshed out.

Here are the other posts I found that sound very similar to my low mpg mechanism, even on brand new Prii!:

Beware of Dealer ECU Calibration MPG way down

Significant reduction in MPG between 2004 and 2005 Prius'

2007 "poor" gas mileage

Gen 2 prius; why is my HWY MPG so high and city so low?

Here is one from a Prius v (Gen 3 drivetrain): Possible undiscovered performance and MPG issues with Prius v (lowercase v)

I also mostly confirmed this mpg mechanism existed with another Reddit user.. but they unfortunately deleted their account a couple weeks later! It occurred in their Prius after disconnecting the 12v battery and replacing the Hybrid Battery. He said doing the commute style I described above fixed it!

Now on to the Evidence.

Testing and Evidence
How do you determine scientifically that your Hybrid Control ECU is in the MAX or WEAK EV state? All you need to do is measure the percentage of gas pedal travel that is allowed while traveling in EV Mode at city speeds before the ICE kicks on. The amount of pedal travel allowed before ICE operation will show whether you have a MAX or WEAK EV state Prius. More pedal travel in EV mode being the MAX state, and less pedal travel being the WEAK state.

Note going forward, pedal travel will also be referred to as Accelerator Pedal Angle due to it being the measurement term. I will use them interchangeably.

The tests below were done using a Bluetooth Code Reader, Smartphone, Torque App, and the Realtime Charts add on for Torque. I'll explain how I did the tests after I convey the evidence.

WEAK EV State Evidence and Testing.
Pedal Angles are much lower in the WEAK EV state for EV mode. When the HV Battery SOC is between 5-8 bars on the display, Accelerator Pedal Angle is limited to a max of 25-35% before the ICE kicks on when traveling between 10-40 mph. The max pedal angle for EV mode is allowed to be slightly higher at 40-50% when accelerating between 0 and 10mph. But for simplicity, we won't be worry about speeds below 10mph as it's to hard to record.

As stated before, SOC effects the max pedal angle in both EV states. For the WEAK EV state, 7 bars of charge will allow closer to the 35% max pedal angle in EV, while 5 bars SOC will be closer to 25% max pedal angle in EV before the ICE kicks on. Also note that up to 11ish% pedal input is "glide". So no force is being applied by MG2 or the engine until past 11% pedal angle.

Below is a screenshot of a of a trip that I graphed with Realtime Charts via Torque in my Prius using my Phone:
View attachment 218639

This trip was done while my Hybrid ECU was in the WEAK EV state. The various lines relate to the legend in the upper right. Their instant value and meaning are displayed to the right of the corresponding color square. The 5 yellow dots hitting the data lines in the center of the graph are attached to the instant values displayed in the legend. So speed that has a value of 16.16 corresponds with the white line where the yellow dot is in the photo. Some graph lines are scaled to make the lines fit the graph better which is noted in the legends as [1.0x] or [0.1x] etc to the far right. The instant value reads 1.0x for all graph lines despite it being scaled when graphed. Instant mpg's are hidden from the line plot because it's very erratic and makes the data look sloppy. The light blue MG2 line is the force the electric motor is applying. This graph is being used to represent what the WEAK EV State looks like. I slowly pressed the gas pedal in succession until the ICE kicks on. This shows what pedal angle activates the ICE in relation to HV Batt SOC.

Here is a zoomed in portion of the above graph showing the WEAK EV State in action:
View attachment 218641

Notice how every time I slowly press the accelerator pedal and approach the 25% pedal angle (blue), the engine (red) kicks on without fail? This is indicative of the WEAK EV State. HV SOC (green) is around 60% and is what causes the Pedal Angle to max out at 25% in the WEAK EV State. Also notice how electric motor torque (light blue) immediately drops off when the ICE engages? See the yellow dots on the graphic for an example of what I'm talking about.

Here is the same thing on a higher HV Batt SOC of around 66%:

View attachment 218640
See how pedal Angles are allowed to be up to almost 35% before the ICE kicks on, but never higher?

MAX EV State Evidence and Testing???
Pedal Angle and MG2 Torque are much higher for EV mode in a MAX EV state Prius before the ICE kicks on. The problem is, as stated in the beginning, I haven't been able to measure the MAX EV state because my Prius has been in the WEAK EV state for the past 1.5 years. I still have not been able to reinitiate the MAX EV state, even with trying experimental commutes.

This is where you guys come in!
To help complete this low mpg mechanism I will need you guys to test your Prii so I can gather the MAX EV state data, prove the MAX EV state exists, and maybe discover why my Prius and others are in the WEAK EV state. I have shown what the WEAK EV state is, I'll need test data from YOUR PRIUS to prove the MAX EV state. I know there are many Prii out there in the MAX state, and maybe we'll get a better idea of how many are effected by the WEAK EV state. There are at least a few as evidenced by the linked posts of other Prius owners above!

How to test this low MPG mechanism yourself.
I will list multiple ways to do these tests. I have made everything as easy and straightforward as possible. With a few $ spent on an OBDII adapter and couple of apps, the testing will be a breeze.

For the preferred method you will need:

1.) An Android Smartphone (Apple users skip these steps, alternative method below)

2.) A OBDII Bluetooth Code Reader to connect to your Smartphone. Any OBD II that connects to your Android phone should work.

3.) Torque Pro App

To get access to the Prius sensors I used to make the charts, you'll have to add the Custom Prius PID's in the settings.

4.) Realtime Charts add on for Torque.

5.) Download my Hybrid Control ECU Analysis Chart Setup for use in the Realtime Charts App. The app will automatically import the chart setup file when you open the app after downloading. All you have to do is then load the chart setup via the app and record data with it. You don't have to go through any trouble creating the chart!

6.) (Optional) - Download my WEAK EV state data file to view in Realtime Charts and compare against your data file. Again, the app will automatically import it after being downloaded and you just have to open it via the Realtime Charts file opener.

7.) RECORD THE DATA!

Max sure your Prius is warmed up with as minimal accessories on as possible and has a relatively high HV Batt SOC. You can force charge the battery by putting the Prius in drive and fully depressing the gas and brake pedal at the same time. Then while recording the data, drive at city speeds between 25-40mph and slowly press the gas pedal in succession to measure when the ICE activates in relation to Pedal Angle.

If the Pedal Angle maxes out at 35%ish or lower for EV mode, you're in the WEAK EV state.

If Pedal Angle maxes out significantly higher than 35% for EV mode, you're in the MAX EV state.

Again, make sure this is done at speeds between 25-40mph and you have a relatively high HV Batt SOC, around 60%.

8.) POST YOUR RESULTS

Then post your results here or at this post!

You can do this by screenshotting the data or uploading the actual Realtime Charts data file for everyone to view. You will have to upload the chart file through something like OneDrive and share the link here.

Apple/Alternative/Cheap Method:
For the alternative method you will need:

1.) Apple/Android Smartphone

2.) A WiFi OBDII Code Reader or a more expensive Bluetooth OBDII Code Reader due to iOS using newer Bluetooth. Android users can still use the cheap Bluetooth Code Reader

3.) A compatible free or paid OBDII scanning app that allows you to create graphs or display sensor data similar to the Torque screenshot below:
View attachment 218637
You will need to add the Prius specific OBDII PID'S to whatever app your using. There should be an option for this in the settings if the app is reputable. You will need to find out how to setup the sensors/data yourself.

It will take some fiddling around to get the settings exactly how you want them, I'm not going to explain step by step how to do it as that will take too long.

Once you get it setup to record the appropriate data, see step 7+ of the preferred method.

If you made it this far...
Thanks for reading and hopefully together we can discover an unknown cause of low mpg. Test away and help me prove my theory!

Any other questions or comments, please ask!

Thanks guys!!!
Click to expand...

You ever see those old V6 Buick Century's/LeSabres on the road that appear to be operated by autopilot?

After passing them you realize that it's just some old lady whose head barely is over the dash. I think the Waymo AI is based on one.

Yeah, I drive like that. I've disconnect the 12V battery more times than I would have cared to do. So maybe thats why I haven't seen a hit in MPG.

Attention Prius Owners, I believe I have discovered a previously unknown Mechanism of Low MPG.

Mendel Leisk Witness Leader

Troy1994 New Member

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Attached Files:

RCMN-20V369-2893.pdf

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Attention Prius Owners, I believe I have discovered a previously unknown Mechanism of Low MPG.

Mendel Leisk Witness Leader

Troy1994 New Member

Frankusa94 Junior Member

Frankusa94 Junior Member

di0tima New Member

dolj Senior Member

Frankusa94 Junior Member

dolj Senior Member

MAX2 Member

MAX2 Member

Frankusa94 Junior Member

Frankusa94 Junior Member

Frankusa94 Junior Member

MAX2 Member

TheLastMojojomo Active Member

MAX2 Member

di0tima New Member

Attached Files:

RCMN-20V369-2893.pdf

dtgpnw New Member

Ford Galaxie Member