Curious economy light behaviour

[andruec]

(No - not another complaint!)

I was driving to work from the dentist today along the B4100 out of Bicester. The main stretch is NSL so I was driving at 60mph. Now it's a fairly flat road but is gradually rising toward the A43 and does have a couple of slightly steeper inclines. What I noticed was that on the fairly flat parts the engine was doing just under 2,000 rpm. On the slight inclines it jumped to 3,000 rpm. Now first off this is not a dig at the CVT. That performed the jumps seamlessly and if it wasn't that I pay attention to the dashboard I'd never have noticed. I didn't even need to move my foot on the pedal, it just changed up then down as it needed to.

I'm guessing that 60mph on that road was right at the cusp of the change in the engine operating mode. What intrigued me though was that the economy lights either side of the speedometer were light blue when the engine was at 2,000 rpm but went bright green at 3,000 rpm. I've seen this before on occasion. Accelerating at 3,000 rpm I sometimes get green lights but when I ease off the lights go blue until I lift off properly.

It seems odd given that presumably the engine was doing more work when maintaining speed up the slightly steeper inclines than when maintaining speed on the flatter bits. I don't think it's a fault but it's curious.

[Skyrider]

I suspect the eco lights are linked to engine load or torque output. As I have a manual car I can control the light colours with my right foot and the gear stick. With a CVT the car changes the gear ratio as you move your right foot so I don't know how you can predict what the lights will do. Most of the time I ignore them and the up/down gear change lights, the only reason they have not been switched off is the boss seems to like them.

Edit

You said that the lights went blue when you lifted off the accelerator, could this be because the CVT changed its ratio up putting more load on the engine?

[edam]

Now I'm changing back to a CVT after driving the manual for 4 months it could be interesting to see the differences apart from the obvious

[andruec]

You said that the lights went blue when you lifted off the accelerator, could this be because the CVT changed its ratio up putting more load on the engine?

Yeah I think that's what's going on. So it might be correct in what it's saying. It's more efficient to accelerate at 3,000 rpm than at 2,500 rpm. Perhaps at 2,500 you're pushing the Atkinson cycle really hard but at 3,000 rpm you're in the sweet spot of the Otto cycle.

[edam]

I think you need to "throw out the rulebook" with this engine.

[VicW]

The ECO light on my 2011 CVT goes out at the slightest hint of an incline when on a fixed throttle.  Put it in Cruise Control and the ECO light never goes out !

Vic.

[Skyrider]

I think you need to "throw out the rulebook" with this engine.

It is not a problem if you know how the Atkinson, Otto, and i-vtec systems interact and use them to best achive economy or performance as you require them. Of course you could just drive it in blissful ignorance of what the car is capable of.

[Skyrider]

I think Honda may have missed a trick! It would be handy if the eco lights indicated green for Atkinson mode, blue for Otto mode, or it could be an option in the setup. Or maybe the trick they missed was explaining what they are actually indicating. They must be more than pretty lights to impress the punters. Green for eco does not mean much.

[VicW]

I doubt that the average owner gives a stuff about what cycle his engine is operating as long as it produces the best overall performance for his/her money. There is quite enough information displayed these days to distract you from the job of driving although said lights could be optional as Deeps said.
That's another ten pages of info in the drivers manual then !

Vic.

[Skyrider]

The lights can be disabled in the Multi-Information Display setup menu. I like to know how my cars work and what dashboard indicators actually mean. They seem to be another version of the Instant Fuel Economy readout in the Multi-Information Display. These could be driven by the MAF sensor and / or computed from the fuel injector timing and duration. I realise the some (most?) people treat their cars like domestic appliances and don't know or care how they work. The fact that a few people use this forum indicates that they have some interest in, or dislike of, their car.

[DWF]

I have noticed that the lights (and the change gear indicator) do behave differently if I am going up a long hill

[Downsizer]

According to page 121 of the Good Book, the so-called "ambient" meter changes from green to blue under aggressive braking as well as acceleration.  I can't say I've noticed this - my attention is elsewhere when emergency braking!  So the lights seem to reflect pedal pressure rather than fuel economy.

[Skyrider]

Maybe I think they are more clever than they really are and they are only an accelerator pressure indicator. :-)

[culzean]

Maybe I think they are more clever than they really are and they are only an accelerator pressure indicator. :-)

most economy indicators only used to measure the inlet manifold vacuum value,  the harder the engine is working the lower the vacuum,

going up a hill or high revs = low vacuum (bad economy)

at tickover and going downhill = high vacuum (good economy)

maybe a bit more sophisticated these days,  with throttle position sensors and ECU but principle is the same