To those who have dabbled a bit more deeply (i.e. ScanGauge or better): The ECO indicator on the HSI (and 1/5 minute consumption) screen seems to indicate an accelerator pedal "setting" at a specific state or lower, and is visible in "D" (not P, R, N, or B driving modes) only, and only in Normal or ECO drive modes. The manual suggests that this indicator will illuminate when the driver is driving in an economical fashion. For the technically minded engineer types, that's a pretty vague description. Has anyone dug in any further to determine if there's a specific throttle % (at the throttle body), accelerator pedal %, power request % (post ECO/Normal mode translation), injector fuel flow, air/fuel enrichment (unlikely), BSFC, EGR state, or other specific criteria that we're meeting or not meeting to trigger this indicator while the ICE is running? Is it entirely arbitrary, or is it continuously fixed to one specific operating parameter? I guess I'm curious on behalf of many on just how Toyota engineers determined what is economical vs. what is not, and what's going on behind the scenes when the light is on vs. not.
I think it's entirely arbitrary - as long as the HSI is not in the "power" zone and you have not selected PWR mode, the Eco light is on (from what I have seen). Not sure if it stays on when you regen or brake, but obviously you're being "economical" then by charging the battery. I haven't tried EV to see if it's still on then - but again, that's all battery. The more I use the HSI, the less useful I think it is.
I think there is a point in the programming of the car at which economy is not paramount, a point where the engine RPM and or other things will be allowed to happen in order to produce more power as opposed to maintaining optimum efficiency. I would like to think this is the point at which the ECO light extinguishes. Of course it could be an entirely arbitrary thing driven purely by the marketing dept., but I hope not. But to answer the original question, no I do not know what trips the light
The ECO light does turn off, even when not in PWR zone and in Normal or ECO mode, when driving faster than 142km/h.
I think possibly then at least that part of it can be correlated to an RPM, above which it's not economical to operate. I think there is more to this light than merely a gas pedal position indicator.
Agree. I was seeing this indicator as the throttle into which the ICE can operate into its most efficient regime (either off or 220g/kWh). Then, depending on your speed, the ICE might have to run faster to avoid MG1 from overspinning, which bumps the ICE out of its most efficient regime. Why does the ECO indicator does not lit in EV mode, normal or PWR even if the throttle is within the efficient range, I do not know. It would have been useful.
I think the ECO light is on even when the ICE is below its most efficient regime - like in the bottom half of the HSI when it's not putting out very many RPM's. And I think this is where pulse&glide proves to be more efficient, by pushing the ICE into the sweet spot for the pulse, and shutting it off for the glide (rather than keeping it on the low end of the range where consumption is less, but efficiency is also less). In short, I think the ECO light is tied to how much gas you are putting into the engine (i.e.: it comes on as long as the flow is below a certain number), not how effectively that gas is being used. This may explain why it goes off above a certain speed even when it's still in the right "range" on the HSI.
From my observation the last few days, my ECO light stays on as long as I am to the left of the PWR range on the right hand side, even when slowing down in regen or CHARGE range on the HSI, all the way down to a complete stop.
Exactly. So (IMO), it must be tied to a fixed fuel-flow number, or possibly a fixed RPM number. (above=bad, below=good, even if it's below the sweet spot) Does anyone know how the HSI calculates the position of its indicator?
I saw this issue previously either here or more likely at cleanmpg. The thinking then was that the HSI is approximating the amount of power requested (not that being produced).
