Optimum shift speeds question - Honda CRZ Forum: Honda CR-Z Hybrid Car Forums

JustSomeGuy · 01-14-2011, 09:19 PM

I originally posted this question over on the new owner forum and it was recommend to me that this may be a more appropriate place, so here goes.

I've only had my 6-speed EX for a couple weeks and my fascination with the control panel hasn't worn off. Given weather and road conditions recently, I've mainly been driving in normal or Econ mode rather than sport.

The odd thing I've noticed is that the "optimum" shift speeds for the manual transmission are listed as 15, 25, 40, 47 and 52 mph in the Owner's Manual (p 207) but the instrument panel is consistently signalling me to shift up to a higher gear (during normal, versus aggressive acceleration) much earlier, up to 20 mph earlier. For example, when I'm already in 5th, it's giving me an up-shift indicator at about 32 mph.

The dealership didn't have any definitive information on this, but thought it might be related to a difference in Colorado's 5000 feet of altitude versus a standard sea level calibration. I could image some amount of difference, but not enough to account for 20 mph.

I'm just wondering if this is a symptom that something's off with the computer or if it needs to be recalibrated. Alternatively, why would the shift indicator be programmed for something other than the optimal shift speeds?

Thanks for any feedback!

northbridge · 01-14-2011, 09:22 PM

nothing wrong. my car wants me to be in 6th gear at around 32 also. Its for fuel economy - nothing more. You can always shift up later than the recommendation with no ill effects.

Currently · 01-15-2011, 02:09 AM

It is easy to let all that instrumentation tell you how to run the car.

Case in point, was following another thread on battery depletion going up entry ramps and hills. Today was the first day I rode my car in some mountain roads ... switchbacks and the like.

With people complaining about battery depletion and sluggishness in mind, I drove the car like it had no battery, I just downshifted into 4th gear and kept the RPM's above 4k and a funny thing happened ...

The battery never went down below 3 bars from full charge, the car had all kinds of power ... and I had a chit eating grin on my face.

There is a time and place for fuel economy and there is a time and place where you need power. Just drive it.

BTW, about a third of the way down the mountain, I had full charge ... 8 bars with the car coasting down on the gears. It was almost disconcerting to see the charge meter inactive because the battery was fully charged.

j_praj · 01-15-2011, 04:34 PM

yes as mentioned above the indicator is for fuel economy. you can change later than instructed with no consequences.

its very easy to let the car take over and let it tell you when to shift...just drive it like any other car no need to constantly check if the indicator is showing to shift up or not

JustSomeGuy · 01-15-2011, 05:34 PM

I agree with all your observations.

Maybe my question is more about how the Honda enginnering team's calculations were interpreted by the team writing the owner's manual, and which ones they chose to document.

I think we can all agree that there are many ways we can drive, each of which is optimal (or far from it) in a different way. For example, keep it in sport mode, jack up the RPMs and optimize the fun.

If the computer on board is trying to optimize the mileage what do you think is being optimized by the shift speeds in the manual? For example do you think it's related to the smoothest acceleration, engine life and maintenance, or something else?

Yeah, I'm a geek.

dr61 · 01-15-2011, 10:44 PM

Quote:

Originally Posted by JustSomeGuy

If the computer on board is trying to optimize the mileage what do you think is being optimized by the shift speeds in the manual? For example do you think it's related to the smoothest acceleration, engine life and maintenance, or something else?

I've seen similar 'suggested shift speeds' in manuals for many makes and models of cars over the years. Never could figure a good reason for printing them. Perhaps these are just a rough median between shift points for maximum acceleration (at or near red line) and shift points for maximum economy (as the shift lights suggest).

01-14-2011, 09:19 PM	#1 (permalink)
JustSomeGuy Junior Member Join Date: Jan 2011 Location: Colorado Posts: 11	Optimum shift speeds question I originally posted this question over on the new owner forum and it was recommend to me that this may be a more appropriate place, so here goes. I've only had my 6-speed EX for a couple weeks and my fascination with the control panel hasn't worn off. Given weather and road conditions recently, I've mainly been driving in normal or Econ mode rather than sport. The odd thing I've noticed is that the "optimum" shift speeds for the manual transmission are listed as 15, 25, 40, 47 and 52 mph in the Owner's Manual (p 207) but the instrument panel is consistently signalling me to shift up to a higher gear (during normal, versus aggressive acceleration) much earlier, up to 20 mph earlier. For example, when I'm already in 5th, it's giving me an up-shift indicator at about 32 mph. The dealership didn't have any definitive information on this, but thought it might be related to a difference in Colorado's 5000 feet of altitude versus a standard sea level calibration. I could image some amount of difference, but not enough to account for 20 mph. I'm just wondering if this is a symptom that something's off with the computer or if it needs to be recalibrated. Alternatively, why would the shift indicator be programmed for something other than the optimal shift speeds? Thanks for any feedback!

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01-15-2011, 02:09 AM	#3 (permalink)
Currently Member Join Date: Dec 2010 Posts: 92	It is easy to let all that instrumentation tell you how to run the car. Case in point, was following another thread on battery depletion going up entry ramps and hills. Today was the first day I rode my car in some mountain roads ... switchbacks and the like. With people complaining about battery depletion and sluggishness in mind, I drove the car like it had no battery, I just downshifted into 4th gear and kept the RPM's above 4k and a funny thing happened ... The battery never went down below 3 bars from full charge, the car had all kinds of power ... and I had a chit eating grin on my face. There is a time and place for fuel economy and there is a time and place where you need power. Just drive it. BTW, about a third of the way down the mountain, I had full charge ... 8 bars with the car coasting down on the gears. It was almost disconcerting to see the charge meter inactive because the battery was fully charged.

01-15-2011, 05:34 PM	#5 (permalink)
JustSomeGuy Junior Member Join Date: Jan 2011 Location: Colorado Posts: 11	I agree with all your observations. Maybe my question is more about how the Honda enginnering team's calculations were interpreted by the team writing the owner's manual, and which ones they chose to document. I think we can all agree that there are many ways we can drive, each of which is optimal (or far from it) in a different way. For example, keep it in sport mode, jack up the RPMs and optimize the fun. If the computer on board is trying to optimize the mileage what do you think is being optimized by the shift speeds in the manual? For example do you think it's related to the smoothest acceleration, engine life and maintenance, or something else? Yeah, I'm a geek.