Topic: Cylinder de-activation systems

[si]

Thought.  With all the traffic these days, and many traffic lights taking a minute or two to show a green light, would it be economically beneficial to turn off your engine at extended wait intersections rather than keep idling.  This would be full cylinder deactivation!  Imagine if you were to spend 10 minutes every day stopped idling doing 0.0 L/100km.  Wouldn't turning off one's engine make an improvement?   All you would do is just turn off your car, put it in neutral and enjoy your fuel consumption rate.

Yes, starting the car does cause wear, but so does idling.  Only major con is for safety sake you may need to accelerate promptly?  It may only save a couple liters every tank but it's a topic worth discussing. 

[AVToller]

Actually, one of the features available on the Vitz (JDM Yaris), but not available on our Yaris is an automatic shut down system when halted at lights, etc. I'm not certain about the exact implementation, but as I recall, they claimed something like an 8% improvement in city driving economy.

[si]

Actually, one of the features available on the Vitz (JDM Yaris), but not available on our Yaris is an automatic shut down system when halted at lights, etc. I'm not certain about the exact implementation, but as I recall, they claimed something like an 8% improvement in city driving economy.

That would be even more substancial on a thirsty V8!

[mdxtasy]

I nominate you to do a test Robo.  Drive one week as you do now in whatever car you are driving...record fuel consumption.  Next fill, do the same but turn off the car at each light.  Monitor the fuel consumption and post the results and savings. 

In addition, I'd like to know how you like to manually stop and start the car at each light.  How much fuel it saves and is it worth it. 

Thanks for volunteering.

[si]

That sounds interesting, too bad I don't drive consistently every week or drive only one vehicle per week.  Also, as much as I don't like paying for fuel, I am not frugal with it It would be easy to calculate potential savings if only I knew how much fuel it took to start a car. 

I know that the engine is thrown a bunch of fuel when you turn the key, but does anybody know precisely how much - say if it's comparable to 2 X idling

At a personal level, saving a few bucks on gas is insignificant, but if every car manufactuer was to implement the technology of the Vitz as mentioned above, there would be huge collective savings.

[AVToller]

The "rule of thumb" that economy experts bandy about is that you save gas by turning of and restarting IF you have to idle for 10 seconds or more.

I agree - 8% city driving savings (if that is the correct figure) would be highly significant.

[chrischasescars]

I nominate you to do a test Robo.  Drive one week as you do now in whatever car you are driving...record fuel consumption.  Next fill, do the same but turn off the car at each light.  Monitor the fuel consumption and post the results and savings. 

In addition, I'd like to know how you like to manually stop and start the car at each light.  How much fuel it saves and is it worth it. 

Thanks for volunteering.

There's no doubt that having to do it manually would be a pain in the ass. And of course, there's the matter of what you would do if you needed to move, right-now-and-fast only to remember that the engine's not running. Hybrids shut down at idle, but they've got the electric motor to back up the gasser. While I think it'd be a great idea - I hate idling at red lights - the system used has to be pretty slick to get the motor running again on less than a moment's notice for those gotta-move-now situations.

[Wetson]

I would volunteer to do this since I mostly do city driving but.... I don't want to put unneccessary wear and tear on my starter.   

[jeeper]

Many mfgs in Europe have it in their compact cars...
Opel Corsa, Fiat Punto...etc etc...i think its a good idea but i dont know how the system will behave in our winter....maybe thats why we dont get it here?

[gta_driver]

Does anybody remember the early  80's fwd Caddy Seville? I think that was one of the first mass produced NA production vehicles to have cylinder deactivation. It didn't work to well. GM hadn't ironed out the bugs.

[ovr50]

gta - IIRC that was the GM V8 called the 4-6-8 engine and it did NOT work very well at all. It was in more vehicles than the Seville I think (Barrie would know better). I believe that technology has come a long ways forward in 20 years.

[mark]

Anybody know what happens to the HVAC system when the hybrids shut off at stoplights?  Does the air circulation system stop?  Maybe a minor point, but this would not be fun crawling in traffic on a summer Friday afternoon, crawling all the way home or to the cottage.

[johngenx]

Hybrids used to have areal problem with running the HVAC system in very cold or hot weather.  Most are now turning to electrically powered systems so that the gas engine can be shut down and the AC run, but the problem in winter still remains as the gas engine loses heat very quickly if you're stuck in traffic and the car's system restarts it to keep the cabin temp as selected.  Hybrids lose some of their advantage in cold climates.  Batteries are not as efficient (yes, even NimH an Lio) and the heater relys on engine heat.