I think I'm getting the hang of it (60 mpg)

Awesome!

 

great job there
Im making a record with my own car as well, but mine is the other way. My km/l rise every day. I blame the job, very heavy traffic and a/c all day

 

That is a primary data point of interest. In theory the HV ECU could use the same calculations I use with the NHW11. What helps would be to see a plot of torque (Y-axis) as a function of rpm (X-axis.) At low rpms, we should see a wide variation of troque but as the rpm increases, we should see it mostly flip between two values, the normal and 'heretical' mode. There should also be some negative values from starting the engine. The variance of torque associated with the ICE rpm helps validate the value.

Don't forget the vehicle ECUs that are formatting the data in response to various direct inputs. They are the source of data but also contribute to data timing variations.

You are asking exactly the right questions. You may also be thinking of "interpolation" versus "replication" where having a series of data points of known time offsets, we assume a linear relationship between two points to 'interpolate' an assumed value. It has to be done carefully with sensitivity to the data sources.

BTW, the CANbus has much higher data rates, Mbps and 100s of Kbps than the ISO 9141 that runs at 10.5 Kbps. The faster CANbus avoids another source timing delays I've had.

Critical to BSFC plots.

Excellent! I had to do an offline analysis but had thought about making it interactive. But it would have been to my laptop and that is a bad way to drive.

The cooled exhaust recirculation may also have an effect by allowing a leaner than 14.7 mixture. You might want to use ICE rpm and injector timing and checking the linearity of MAF vs calculated fuel flow. The slope should be ~14.7 but any variation suggests cooled, exhaust gas recirculation.

I know, welcome to the 'leading edge.' <grins>

Ignore the throttle. We want something a dyno can not supply, the ICE efficiency 'in the field.'

Knowing the efficiency in the field gives us ICE efficiency in different operating modes such as acceleration, highway speeds and hill climbs. Once we correlate the vehicle efficiency boundaries, we can avoid 'the dark side' of vehicle performance. This leads to what I call "Johnathan Livingston Seagull" moments where we learn how to achieve optimum performance for minimum costs.

Works for me.

I was lucky to get a Graham Miniscanner that was developed by an excellent engineer. The 50 some odd data elements happen to be the ones needed for vehicle efficiency studies as well as maintenance. But it also takes careful attention to data collection and analysis.

You are doing excellent work and I'm just happy to share my 'lessons learned.'

Bob Wilson

 

The speed of the CANbus means we don't have to deal with the rather lethargic ISO 9141 at 10.5 kbs.

These are the leading edge questions where a lot of folks are looking.

I've been reading the datasheets on the CANbus and the addressing scheme is listen-while-talk and perfectly detect a collision. Based upon the address of the node, the high priority, defined by the node, 'wins' and the other waits for the next window.

I wish but mostly I use the datasheets for the interface chips. FYI, ISO 9141 comes in two flavors, fixed length and variable length KWP2000. They do use separate signals.

The real problem with our NHW11 is one of the CAN bus lines is also mapped into the Ts/Tc lines a 'jumper' technique to trigger code flash and reset. This causes many scanners to trigger false error codes on the NHW11 ABS. But that is another problem.

Bob Wilson

 

In your text file at the bottom. There is information about GPS "Device: j-Generic GPS Version:2.1.3-2022". Is that comming from the DashDAQ or the Prius? If is't comming from the Prius then we could save $80 not buying the antenna.

 

Very impressive accomplishments as far as mpg!

I've only had my 2010 since end of May but it's going up since getting it. Using A/C really makes a difference, and since most of of my trips are severe city driving I think I'm doing quite well.

I'll post my pics later but average about 52mpg - 48, 54, 54 (4 fill ups). (actual calculated mpg).

I am working on a tank with 200miles and a little over 61 mpg on computer... As cooler weather arrives, my mileage hopefully should improve...

ps: used to always use cruise control, now I never use it...

 

Hi all,

This thread has been REALLY helpful for maximizing my mpg over the last few weeks. For example, on my 20-mile commute that includes both highways and surface streets I normally average around 60mpg. (I once got 73mpg but had no idea how I did it.). Well, today, on the exact same commute I got 78mpg indicated. I was amazed. Here's a summary of the approach that I used, based on the info in this thread and the various links:

Starting
- I Pulse/accelerate with the HSI just below the power area. (This isn't the exact sweet spot for the engine, but it's pretty close and gets me up to speed in a reasonable time.)

Non-Highway Driving
- Once I get up to speed, i do pulse and glide. Pulse is done at a level on the HSI just under the right side of the ECO symbol. (This is the sweet spot of the motor at 15kw or 20HP.)
- Where road conditions allow, I only pulse to 44mph so that the motor doesn't start to spin and create a 5kw drag. (it really is amazing how far the Prius will glide at 44 mph compared to 46 mph). To stay under 46mph I sometimes even find the need to glide up a hill for a short time to bleed off a few mph.
- Of course I also do a little anticipatory driving on hills where I accelerate on a downhill or on a flat area leading to a hill, and then bleed off some speed on the uphill. (Unless I'm careful I tend to slowly accelerate up hills, with the speedometer incrementing another mph every 5 seconds or so. If I'm already at a reasonable speed I have to intentionally back off the throttle a bit to keep speed constant instead.)

Highway Driving
- Similar to non-highway mode, I try to pulse or maintain speed with the HSI at just under the right side of the ECO symbol. On the highway, during low load conditions, my challenge is to not let the HSI drift down to just above the centerline, as this is where the efficiency of the motor starts to drop off dramatically. (This is still a bit strange to me, since the links in this thread mention that efficiency is lower at this HSI reading. However, the instantaneous mpg display shows as quite high...) In those low load conditions, I don't hang around the centerline anymore, but instead lay off of the throttle and then slightly press it again to cancel out the regen.
- I try not to exceed around 65mph since the air resistance begins to get much higher and I can't maintain speed at the pulse level described above.
- Of course anticipatory driving on hills applies here too.

Misc
- Note that I rarely if ever run on battery power anymore. This is a key piece of advice from experts on the forum. This too was counterintuitive to me, because I could see my average mpg going up whenever I ran on battery-only power. However, what I couldn't see later on was the cost and inefficiency of making up that battery state of charge with the engine.

I hope this helps others. I'm looking forward to gaining more experience with this approach, and tweaking as I go.

 

I do believe you are getting the hang of it....I too am in Maryland and depending upon the weather I am either running the AC or the windows are down. Right now my best to date is 68.4 mpg and that is traveling the posted rate of speed, no sudden accelerations and decelerations and making sure not to carry heavy loads. My neighbors still can't believe I bought Prius but then when I am at the pumps once every 8-10 days and my gas last month was less than $100 total including a round trip to Philly and back. This car is going to more than pay for itself in the first three years.

 

On the first and second pictures of post 37 - Is the HSI bar too far to the right of the center line to be considered under the ECO bar? It looks like if from the center line to the Eco bar = x distance, in the picture on 37, the bar is 2x from the centerline. In the Highway mode that produces ~15kw of power, I'm assuming the bar should be around "x" where "x" is the bar lined up under the right edge of the ECO symbol.

Correct?

 

I think it was Hobbit's post (or linked via it) I was thinking of in regards to the Eco bar. My interpretation from the post was the actual <ECO> symbol that straddles the middle bar of the two fat bars. And that the most efficient spot to be in was to the right side of the word <ECO> but not extending much past it (in fact, maybe to try to line up underneath it), which would be approximately 1/4 of the distance between the center line and the PWR border line.

 

Very encouraging indeed!! Grats!

 

I'm not expert or mechanic either, but the way the Prius' brakes feel, I bet it as conventional brake, but with regen braking added as an extra boost. The sensor reads pedal position and appropriete regen braking is added to the mechanical braking force. Ie. the higher pressure on the pedal, the higher percentage of braking from friction. IMHO, there is no way brake is "fly by wire" operation, it is always attached mechanically just like the Prius' steering wheel (electric power steering giving a boost of course) for safety reasons.

Any Prius mechanics who can chime in?