[bwilson4web]

Hi,

I recently had my ScanGauge upgraded to V4.x to work with the 2010 Prius. So far, the standard features appear to work just fine. I had not been using it in the ZVW30 but I'd volunteered to test it with my wife's car that has 19,000 miles and 10,000 miles on the tires.

The ScanGauge has a number of setup values that need to be tweaked:

• fuel type -> hybrid :: tends to set the sleep mode so when the engine goes off, the ScanGauge continues to run
• engine -> 1.8L
• tank size -> 12 gallons :: in fact, our car appears to have 12.1 gallons 'to dry' but this will take at least 3-4 weeks to test.

Initially, the indicated ScanGauge speed indicator was off reading 48 mph at an indicated GPS and speedometer reading of 50 mph. So I changed the ScanGauge speed adjustment by +4% to bring the scangauge, GPS and indicated speeds within the display limit, 1 mph, @50 mph. To gain more resolution, I used a trip report:

57.2 MPG, 38 mph, 13.8 miles - ScanGauge (+4%)
58.0 MPG, 39 mph, 13.5 miles - ZVW30 Prius

The trip report suggests that for an exact match on miles and speed over a trip, the correction factor needs to be +5% which I'll test this morning and compare with the GPS.

In 2009, the collected PriusChat reports showed a 5% optimistic error between the indicated and actual MPG mileage. This suggests the ScanGauge speed adjustment could be tweaked to give an accurate, live MPG and use GPS and indicated speed for velocity and distance measurements. One caution, this 5% calibration and the earlier error could just be coincidence:

Looking at the 50 MPG line, the actual appears to be 47.5 MPG, a 2.5 MPG or 5% optimistic indicated report versus the pump measured 50 MPG.

Also testing the ScanGauge, I found the best sleep-mode, trigger is "voltage." I was looking at the options with the car parked and engine off and just as I saw "rpm", it went to sleep. <grrrr>. I also tested "CMD" but came back to find the ScanGauge still running after being parked for several hours. So far, "voltage" appears to be the best bet.

So far, a few setup tweaks helps the ScanGauge to work with our 2010 Prius, ZVW30 model.

Bob Wilson

[bwilson4web]

bwilson4web said:

. . . To gain more resolution, I used a trip report:

57.2 MPG, 38 mph, 13.8 miles - ScanGauge (+4%)
58.0 MPG, 39 mph, 13.5 miles - ZVW30 Prius

The trip report suggests that for an exact match on miles and speed over a trip, the correction factor needs to be +5% which I'll test this morning and compare with the GPS.

So I used the longer, faster and less fuel efficient route:

To Work (no AC, 81F):
54.1 MPG, 40 mph, 13.4 miles - ScanGauge (+5%)
**.* MPG, 45.1 mph (moving), 13.2 miles - GPS
54.8 MPG, 40 mph, 13.1 miles - ZVW30 Prius

Lunch (no AC, 90F):
58.8 MPG, 38 mph, 15.7 miles - ScanGauge (+6%)
**.* MPG, 37.7 mph, 15.6 miles - GPS
58.9 MPG, 38 mph, 15.4 miles - ZVW30 Prius

Return from Lunch (with AC, 95F):
53.1 MPG, 49 mph, 15.5 miles - ScanGauge (+6%)
**.* MPG, 48.7 mph, 15.3 miles - GPS
51.8 MPG, 50 mph, 15.2 miles - ZVW30 Prius

So tweaking the ScanGauge setup for speed adjustment has an effect and seems to be bringing it closer to the ZVW30. One more pass at 6% may be the charm. However, this will likely get the distance and speed right but won't correct for the built-in, indicated MPG error. Sort of a 'pick your poison.'

Bob Wilson
ps. My tires are Toyota replacement, Sumitomo T4, P195/65R15

[billysbarn]

Hi Bob
I finally made the leap of faith and bought an SG2 from the distributor int the UK as he assured me the bugs had been sorted!
Can you please tell me how to input the codes into XGAUGE? (and how to use them?)
Can I connect it to my PC and upload them or do I have to type them in?
Do you have any tips as to how to program the XGAUGE?
Thanks
Billy

[jdenenberg]

Biil,

Read the xGauge instructions in the manual and the details at::

http://www.scangauge.com/support/toyota-specific/
Which includes a link to more xGauge definitions.

You do have to type them in using the procedure in the manual.

JeffD

[bwilson4web]

JeffD is right but not to worry. You will get a lot of help.

Let me suggest the first step is to install the cable and route it up to where you want the ScanGauge to be. You will want to reach it easily while keeping a weather eye out for traffic. It took me two tries to find the right place so be flexible. It is more important to get the location right than anything else.

Ok, let's get some basics out of the way. Start the car and using the ScanGauge menu, find out what version you have. Also, we want to make the ScanGauge match your car:

• displacement and year? The NHW11 is ISO-9141 but the others are CANbus
• fuel type - make sure it says "hybrid"
• stop - depends upon your car

BTW, you are in luck as I've had several recent epiphanies about Prius performance and we'll tailor the ScanGauge so you can exploit them. <GRINS>

Bob Wilson

[billysbarn]

Thanks Bob.and JeffD
Now installed on steering column using magnets and steel strips with double sided sticky pads.
Set to Hybrid. (Lexus Rx400h)
Displacement 3.3 litre
Not sure what "stop" means?
Many thanks
Billy

[bwilson4web]

Good deal!

For now, start with these four built-in gauges:

• gallons per hour (or the metric equivalent) - it turns out that better than miles per gallon, the rate of fuel burn is one of the better indicators of the transmission state. I'll cover this in more detail later.
• coolant temperature - the Toyota hybrids have two major operational modes: warm-up under 70C and operational above 70C.
• engine RPM - this is used to make sure the car has fully passed into the operational, hybrid mode.
• miles per gallon (or metric equivalent) - this will help show how 'driving the load' measured by gallons per hour or the metric equivalent pays benefits.

COLD-START

From cold-start the engine tries to burn fuel just to warm-up the car and most of the power comes from the traction battery. For example, my 1.5L Prius shows:

• ~0.30 gallons per hour in "N" - regardless of speed, this is the minimum fuel burn rate of this engine. This is close to the 1.8L Prius minimum fuel burn rate. You'll need to measure it for your car.
• ~0.60 gallons per hour plateau in gentle acceleration - as you speed up with gentle application of pedal, the car will draw power from the traction battery. The car energy display will show the current from the battery to the wheel motors. Our 1.8L Prius has a little higher, warm-up fuel burn. I suspect the ratio is roughly 2:1 but you need to observe it with your car. As your car speeds up, the initial, cold-start will reach a point where this slightly higher plateau goes away and fuel consumption will jump up and the engine rpm increase.

The duration of cold-start lasts from 45 seconds for our 2003 Prius and nearly 200 seconds for our 1.8L Prius. But by gentle acceleration on EV power, the car can reach 35-40 mph with impressive, high mileage values. By shifting into "N" while rolling, the car MPG will shoot up to very high values and you can easily achieve 30+ MPG.

Sorry, I forgot to ask, do you prefer liters over gallons and km/h versus mph? Sad to say, my numbers are the smaller USA gallons.

WARM-UP

Until the engine coolant reaches 70C, the engine will run at every opportunity and not necessarily in the most fuel efficient mode. During this time, I use "N" in my glides to unload the engine and then shift into "D" if I will be slowing down or stopping for regenerative braking. In this mode, I try to take neighborhood routes, 25 mph, and maximize use of "N" to avoid inefficient fuel burn. This takes about a mile in the summer and a mile and a half in the winter.

OPERATIONAL

It turns out the Toyota systems have a 'normal' and 'energy recirculate' mode that works to slow engine rpm. But the engine is so quiet and transmission so smooth it is almost impossible to tell. The effect is a 2x ratio of fuel burn. When in the more efficient 'energy recirculate' mode, the fuel consumption at a given speed on flat terrain will be a minimum and the instantanious fuel consumption show a peak. But if more power is needed to speed up or climb a small grade, it will switch out of 'energy recirculate' and into 'normal' mode with nearly twice the rate of fuel consumption. I'll post a graph later to show the two modes.

You can extend the 'energy reciculate' mode by lightening the accelerator. As for the 'normal' mode, if you can use a downgrade to speed-up, you don't have to go into higher power, higher fuel consumption modes. But it turns out that there are modest power modes that handle acceleration without burning a lot of fuel.

One other thing is there is a critical speed below which the hybrid can turn off the engine and use traction battery. Above this speed, the engine has to run all of the time even if not producing much power (or burning much fuel.) For the 1.5L Prius, it is 42 mph. The 1.8L Prius threshold speed is 46 mph. I don't know what it is for your car but it can be measured.

Find a hill, longer is better, that with the car in "D" it continues to gain speed. Starting at say 35 mph at the top, take your foot off the accelerator and let the speed build up while watching the engine rpm. When you reach the threshold speed, the engine will start. This is an important speed for efficient driving.

If you can take routes where the speed limit is below this threshold, the car will automatically cycle between engine and battery power and you will get really good mileage. With a 'guard band' of say 4-5 mph below it, you'll get great fuel efficiency. Above this speed, you can still get good mileage by moderating the higher power settings, the gallons per hour of fuel burn and staying in the 'energy recirculate' mode.

Bob Wilson

[billysbarn]

Hi Bob
That's very helpful.
Actually I prefer miles and gallons! Sorry!
I presume you have established it is safe to travel in "N" neutral?
My last car was a Saab 9000i auto and the Saab handbook said not to coast in N or be towed in N over 30 mph or it would damage the transmission.
Just checking!!
BTW, when the SG2 says zero RPM, is the engine still rotating without fuel?
Also, I notice that the SG mpg reading is a lot lower than the built in MPG readings.
The SG gave an average 50 mile trip today of approx 32 mpg, yet the car gave approx 39 mpg (UK gallons of course)
Could that be because the SG has yet to be calibrated or is the lexus lying?!!!!
Thanks
Billy

[billysbarn]

PS, I forgot to mention the SG MPH reads exactly the same as my GPS which reads exactly 4 MPH less than the speedo throughout the speed range.
Also, the SG is set to Hybrid and goes to sleep a few seconds after turning off the engine.
So no corrections needed there
I hope to get my Enginer phev kit fitted permanently in the next few days. I had to remove the temporary set up to make room for luggage for my daughter

[bwilson4web]

billysbarn said:

Hi Bob
That's very helpful.
Actually I prefer miles and gallons! Sorry!

Here in the USA so do we but I'm also happy to post metric. Normally I do both but for now, we'll leave it in 'English' units.

billysbarn said:

I presume you have established it is safe to travel in "N" neutral?

Yes, because unlike traditional hydro-mechanical transmissions, there are substantially fewer moving parts and they are not nearly so dependent upon engine power being on. In the Prius transmissions, there is a small oil pump that is driven by the engine BUT this is a hybrid and below the critical speed, 42/46 mph, the engine goes off anyway!

billysbarn said:

My last car was a Saab 9000i auto and the Saab handbook said not to coast in N or be towed in N over 30 mph or it would damage the transmission.
Just checking!!

According to the Toyota documentation, the car should not be left in "N" with the engine off and allowed to coast down a hill faster than the 42/46 mph limit. What happens is it spins MG1, the engine counter-torque motor generator, faster than it is designed to work. However, I and good Prius Friend Hobbit have done the forbidden experiment, me to 49 mph and Hobbit faster. So far, our MG1s have enough reserve strength to not fly apart. But I make it a point to shift into "D" if going down a hill and reaching 42/46 mph so the engine will start and then back to "N" so it idles at a minimum fuel burn rate.

Now once I reach the descent speed I want, I shift into "B" and let the engine handle most to the braking going down a hill. The reason is this avoids putting a heavy charge on the traction battery, an exothermic reaction. If you are driving through hilly country, say 100-150 m hills, the ascents and especially the descents can 'heat pump' your traction battery to much higher temperatures. Using "B" on the descents is a great way to get down the hill without 'heat pumping' the battery, having to use brakes, and generally enjoying the view. We have three shift positions and with my feet flat on the floor, I use "N", "D", and "B" to maintain the desired speed. <GRINS>

One other thing, if you are doing mountain or tall hill driving, I like to use a heavy lorry or truck as my hill-climb pacing vehicle. Their power-to-weight ratio means they climb hills at a very efficient, hill climb speed for a Prius. I don't tail gate but use them as my pacing vehicle as their rate up the hill is just about the optimum conversion of fuel energy to altitude at a reasonable speed.

billysbarn said:

BTW, when the SG2 says zero RPM, is the engine still rotating without fuel?

It is not rotating but you will see a small, 0.02 GPH, so the miles per gallon calculation won't blow up with a divide by zero problem.

billysbarn said:

Also, I notice that the SG mpg reading is a lot lower than the built in MPG readings.
The SG gave an average 50 mile trip today of approx 32 mpg, yet the car gave approx 39 mpg (UK gallons of course)
Could that be because the SG has yet to be calibrated or is the lexus lying?!!!!

What is the ratio of the US gallon to the UK gallon? I suspect the ScanGauge is showing our smaller, USA gallons per mile. But I just checked the User Manual and it looks like there are only two alternatives, liters and gallons.

The folks at ScanGauge support are very helpful and if you send them a note, they may have a fix that allows use of Imperial gallons instead of our Yankee, undersized gallons. <GRINS>

billysbarn said:

PS, I forgot to mention the SG MPH reads exactly the same as my GPS which reads exactly 4 MPH less than the speedo throughout the speed range.

Some of our EU friends have reported that there is a requirement that the EU speedometers show higher than true speed to 'fool' drivers into going slower. Since I use different size tires than stock, I go by GPS speed.

billysbarn said:

Also, the SG is set to Hybrid and goes to sleep a few seconds after turning off the engine.
So no corrections needed there
I hope to get my Enginer phev kit fitted permanently in the next few days. I had to remove the temporary set up to make room for luggage for my daughter

Excellent!
The parameter I was trying to remember is called "Sleep Event" and it sounds like setting the car type to "hybrid" now means you don't have to fiddle with it. In my case due to the earlier software, I have used either 'volts' as in the 12 V battery voltage going low or CMD as in the vehicle stops communicating. But the V4.02 and 4.05 seem to have fixed this area.

Bob Wilson