MPG vs mode for 6MT cruise control - Honda CRZ Forum: Honda CR-Z Hybrid Car Forums
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post #1 of 26 (permalink) Old 02-02-2017, 04:09 PM Thread Starter
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MPG vs mode for 6MT cruise control

Took my first long (~1K miles) interstate trip in my 2016 CR-Z. I was going about 65 mph on I75 south and switched between normal and eco while in 6th gear with cruise control on. The instantaneous mpg indicator was several bars higher in eco mode than in normal, but the ima battery charge slowly dropped while in eco mode. Once the ima battery charge indicator got down to about 2 or 3 bars the mpg indicator dropped and switching modes didn't make any difference.

Interesting.

I should have tried sport mode as well but didn't think of it.

For the first half of the trip I averaged 40 mpg. I was able to go 70 mph on the homeward half of the trip due to less traffic; overall at the end of the trip I got 39 mpg.
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post #2 of 26 (permalink) Old 02-02-2017, 04:56 PM
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Yes, interesting. Just the sort of testing I never remember to do.

I don't think we've hit a consensus on the mode change effects. It seems that if you're doing a lot of hills or traffic, Sport will often give better mileage than Econ.
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post #3 of 26 (permalink) Old 02-02-2017, 05:06 PM Thread Starter
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I would really like to see a clear, detailed description of the algorithms used by the IMA charge/assist in the 3 modes. I did see plots of throttle vs gas pedal position for the 3 modes, although I can't remember where.
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post #4 of 26 (permalink) Old 02-02-2017, 06:06 PM
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I would really like to see a clear, detailed description of the algorithms used by the IMA charge/assist in the 3 modes. I did see plots of throttle vs gas pedal position for the 3 modes, although I can't remember where.
The maps of IMA assist are around here somewhere, did you read any of the several dozen threads on the subject?

Which 'Mode' do you drive in the Most?

Who mostly uses Normal Mode?

better mpg in sport mode

Eco Mode MPG vs MPH

Most Economical Driving Mode

Fuelly Statistic and profile Thread

http://www.crzforum/forum/honda-cr-z...ing-modes.html

Which Mode Do You Drive in Most?

Normal vs Econ vs Sport - how do you use them?

Maintaining fuel economy when driving up a mountain



Also suggest not going by the vehicle's computer alone and doing fill-up to fill-up calculations with exact miles driven and fuel pumped to compare, leaning towards the actual measured results over the vehicle computer. And focusing less on the instant mpg gauge and more on right foot discipline.

I don't know that you'll find any more detailed an image than the one thats been shared around here. You can pull all the data off the ECU and analyze it or just go by the information, observations and experiences owners have been sharing here for years or do your own testing. Personally I'm in normal mode almost entirely, cruise control 6MT cross country freeway driving can be 38-50mpg.
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post #5 of 26 (permalink) Old 02-03-2017, 08:19 AM Thread Starter
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Thanks Koala Yummies! I've read some of these threads, but not all.

I drive mostly in normal. Eco seems to work well for stop-and-go traffic.
I've noticed eco mode almost always engages auto stop; normal sometimes
leaves engine running when it is cold out. Got the car in October, so haven't used
the AC yet.

I use sport on "interesting" roads.

I don't really obsess with mpg, but love seeing it above 40!

And as an engineer, I'm really interested in figuring out exactly what the car is doing.

Totally agree with "right foot discipline".

Did test in cruise control to remove "right foot" variable.
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post #6 of 26 (permalink) Old 02-04-2017, 12:44 AM
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.....
I've noticed eco mode almost always engages auto stop; normal sometimes
leaves engine running when it is cold out. .....
If the defroster is on, Auto-Stop doesn't. I'm sure that applies to when the heating system engages the defroster during its auto function.
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post #7 of 26 (permalink) Old 02-04-2017, 10:18 AM
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ECO is trying to maximize mileage so it does use more Auto Stop. This works as designed.

I find it amazing the car has all of this with a manual transmission. It hurts my head to think about all of the decisions this system has to make as you drive and stop.

Quote:
Originally Posted by ptsmith View Post
Thanks Koala Yummies! I've read some of these threads, but not all.

I drive mostly in normal. Eco seems to work well for stop-and-go traffic.
I've noticed eco mode almost always engages auto stop; normal sometimes
leaves engine running when it is cold out. Got the car in October, so haven't used
the AC yet.

I use sport on "interesting" roads.

I don't really obsess with mpg, but love seeing it above 40!

And as an engineer, I'm really interested in figuring out exactly what the car is doing.

Totally agree with "right foot discipline".

Did test in cruise control to remove "right foot" variable.
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post #8 of 26 (permalink) Old 02-04-2017, 01:19 PM
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And as an engineer, I'm really interested in figuring out exactly what the car is doing.
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ECO is trying to maximize mileage so it does use more Auto Stop. This works as designed.

I find it amazing the car has all of this with a manual transmission. It hurts my head to think about all of the decisions this system has to make as you drive and stop.
Yeah, its a damn programming nightmare thats what it is! Think of all the parameters and variables and how many times "if x = then y =" had to be programmed into the computer and then multiply by 3 for the different modes.

A few variables just for the control of auto-stop engagement: engine temperature, HVAC settings, defrost settings, vehicle speed, gear in or out, clutch in or out, brake pressure and likely more.

Thats one operating parameter for one thing with all those variables.

OP if you're interested in more information the official service manual 'Helm' has a sizable section on the IMA system, you should be able to find a link to an online copy around this site. It can help explain some of the system and operating decisions a little further but it still doesn't list exacting parameters (like precise level of IMA motor assist per given RPM, throttle input and drive mode for example). Those would all be in the ECU software. And even then those values change depending on certain factors (charge level, engine temperatures, battery temperatures and so on).
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post #9 of 26 (permalink) Old 02-05-2017, 01:30 AM Thread Starter
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I find it amazing the car has all of this with a manual transmission. It hurts my head to think about all of the decisions this system has to make as you drive and stop.
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Originally Posted by Koala Yummies View Post
Yeah, its a damn programming nightmare thats what it is!
I wonder if the CVT version is an easier or harder problem. It has the extra work of shifting, but on the other hand it doesn't have to take into account a driver who doesn't shift when the system thinks it's time to shift.

In any case it is an impressive feat that Honda got it to work so transparently.
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post #10 of 26 (permalink) Old 02-05-2017, 08:31 AM
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I think the best thing is I can just get in and drive and for the most part it decides what to do with all the fuel saving features.
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