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Thread: Shutting off engine at red lights?

  1. #21
    Quote Originally Posted by Anonymous View Post
    Not to mention extra wear and tear on the starter.
    I was just about to say this. On top of this, engine start up causes up to 90% of engine wear.
    Yes its already warm, but your letting all the oil settle then a "less" lubericated engine is started.
    Regardless of engine temp, the ecu will raise rpm and enrich fueling until it checks all sensors. This takes a few seconds to minutes,
    Hell, my catalytic temp doesnt operate until its at least 165 F, I assume the o2 sensor( which controls fuelling ) also isnt fully operating once the engine is turned off, until it cycles up to temp again.

    Short trips and start/stop will increase fuel unless the ecu is designed to operate in those conditions and thus have the appropriate programming to understand this is a red light stop/start, car only understands "im on, and now im off, im on" just like a laptop , desktop or cell phone, the default start up protocol is to cycle first, then determine what to do. Until it figures this out it assumes it must use the enrichment startup table.

    Hope that all makes sense.


        __________________________________________

        click to view fuel log View my fuel log 2015 Micra S manual: 7.7 L/100 km ... 36.8 mpg (Imp) ... 13.0 km/L ... 30.6 mpg (US) ...


  2. #22
    Quote Originally Posted by Daox View Post
    Yes, I do turn my engine off at lights. Actually, my engine is off before I get to the light. I see no point in running the engine if I'm headed towards a red light. If it turns green on the way, I start the car up and go. If I must stop, I wait and when it turns green (or is about to turn green if I can see the cross light) I start up and go.

    As for the pulse and glide, it is used in appropriate situations and traffic patterns. For instance, in light traffic I use hills when using pulse and glide to maintain a more normal speed (pulse up, coast down). I don't typically do it in heavy traffic if its only a single lane road so as not to annoy other drivers. Typically, there is not much more speed variation than anyone else, and certainly less than someone on a cell phone.

    I also rarely exceed the speed limit. I'd say more people are annoyed by me actually driving the speed limit than any variation in speed they may notice. To that I say tough. Its the law and I do try to obey it. I'm certainly not going to disobey it just because someone else thinks I should. They certainly won't be paying my ticket if I am caught.

    No doubt this is an odd driving technique to most out there. It is also pretty advanced in the slew of fuel economy driving techniques that are used to get better fuel economy. That being said its also highly effective, and if you're really wanting good mileage its worth looking into.
    How do you save fuel by shutting off the engine when approuching a light.
    Our cars inject nothing when whinding down. The IGN TIMING goes to -15 and a/f r goes to 29.8:1 ( meaning so little fuel it doesnt even acknowledge there is fuel. The l/100km drops to 0.00

    The only thing your doing is;
    Locking your steering wheel, disabling abs, disabling thottle, disabling electronic steering assist, and your sensors should someone rear end you, your airbags wont deploy and the event data recorder will see that the last thing you did was turn off your car while in motion. Which will put you "at fault" regardless of who hit who.
    Your cooling fans which would normally turn on, are off. Allowing your engine to sit in it heated stated.

    To summerize; i doubt your accomplishing what you mean to, and your leaving yourself liable and at risk. And risking other people "potential" safety to save what? A few cents?!???

    So those lights on the front of your car, they use electricity, which robs power ( thus fuel economy ) from your engine. Might as well rip those out. Side mirrors, aero. Remove those.

    I mean youll be lighter and have less power robbing parasites, and saved a couple more cents...

    * * * slow clap * * *

    Rant/

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra S manual: 7.7 L/100 km ... 36.8 mpg (Imp) ... 13.0 km/L ... 30.6 mpg (US) ...


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  4. #23
    Administrator Daox's Avatar
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    Its not illegal in the least. Its also really not dangerous if you know what you're doing and know how to drive that way. The same could be said of driving in general. Driving in general is dangerous unless you actually know how to drive. Same with flying a plane, using heavy machinery, etc. This really isn't any different, its just uncommon.

    As stated, engine wear is increased. However, it is minimal since its not a cold start with all the oil in the sump. I've personally never had an engine or starter issue in the 10 or so years I've used the technique. Thus I consider it a non-issue.

    The fuel saved turning the engine off on the way to the light is not as much from not having the engine running as much as maintaining momentum. The key really is to not have to stop for the light at all. If I'm going 35 km/h when the light turns green vs 0 km/h that is that much less fuel I need to burn to accelerate back up to speed. In certain cases I may employ engine braking to do this. That is a viable technique though often not the most efficient.

    Again, knowing how to drive this way is key. I'm not disabling any car features. The engine is killed, but the car is not turned off because I do it via a momentary switch that kills power to the injectors or ignition system. ABS, electric power steering, airbags, cooling fans and everything else electric is unaffected. Hybrids these days do this all automatically, and more and more non-hybrids are starting to use start/stop systems to save fuel. My techniques are no different other than there isn't a computer controlling them.

    I personally don't do this so much to penny pinch. I own fuel efficient cars that are efficient to start with, however this does increase fuel economy even farther. Mainly, I find it quite fun to drive this way, and I enjoy trying to beat my own high score. So, it becomes a sort of game. The additional fuel savings is a nice perk I admit. Driving normally is boring IMO. Driving aggressively can be fun, and I do enjoy this aspect of driving as well from time to time (usually on my motorcycle). But, it also can become frustrating quickly as traffic gets in the way.

    I'm not sure why this riles people up so much except that they don't understand what is actually going on and assume the worst. If you don't like this way of driving don't do it lol. You're not gonna ruffle my feathers, and I'm not making anyone drive a certain way. I'm simply explaining how I do it and how you can save fuel. So, I hope that clears up some of the misconceptions and questions, but feel free to ask away if there are more.

  5. #24
    Senior Member micrapolis's Avatar
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    everything i've read about this (and related) behaviors support that IMPUL says.

    it's not worth putting ppl at risk.

    anyways, im done here.

  6. #25
    Senior Member lbarouf's Avatar
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    As a side note, I changed my commute for a less traveled path. I have roughly 40Km each trip with a total of 12 lights. I cruise at 80km/h on average, and avoided the highway. That on average means for me I can do 5.7L/100Km (real). I am lucky enough to be able to choose hours that are less affected by traffic, and having options in routes. But in the end what I mean to say, is I see better benefits of a steady drive at steady speed, vs trying to go through extreme measures to same on gas in traffic. I'm no hyper miler, but sure am conscious of waste.

    Just my 2 cents. And no, I would not consider stopping the car unless I know for sure I will be stuck there for more than 2 minutes like when they close the darn 401 for accidents (thank you rubber neckers).

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra S manual: 7.7 L/100 km ... 36.6 mpg (Imp) ... 13.0 km/L ... 30.5 mpg (US) ...


  7. #26
    Senior Member dani3d's Avatar
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    You don't have to shut off the engine to avoid stopping at a red light, you just have to lift your foot from the gas pedal and the engine drop to 0 fuel consumption then you just coast to the light the same way if the engine would be shut off, except you retain all controls. Much safer and does not cost more fuel. I coast to red lights all the time that way.

    Because of that, it's not worth shutting off the engine before the car is fully stop because one might not even need to do so because the light will turn green. There is really no advantage of doing this. I don't even see an advantage in shutting off the engine if the light is not long enough.

    If you have modified your car to have a system for engine stop and start then it's probably safe, but most Micro owners will not have this system and would probably be at risk by doing what you do.


    Quote Originally Posted by Daox View Post
    Its not illegal in the least. Its also really not dangerous if you know what you're doing and know how to drive that way. The same could be said of driving in general. Driving in general is dangerous unless you actually know how to drive. Same with flying a plane, using heavy machinery, etc. This really isn't any different, its just uncommon.

    As stated, engine wear is increased. However, it is minimal since its not a cold start with all the oil in the sump. I've personally never had an engine or starter issue in the 10 or so years I've used the technique. Thus I consider it a non-issue.

    The fuel saved turning the engine off on the way to the light is not as much from not having the engine running as much as maintaining momentum. The key really is to not have to stop for the light at all. If I'm going 35 km/h when the light turns green vs 0 km/h that is that much less fuel I need to burn to accelerate back up to speed. In certain cases I may employ engine braking to do this. That is a viable technique though often not the most efficient.

    Again, knowing how to drive this way is key. I'm not disabling any car features. The engine is killed, but the car is not turned off because I do it via a momentary switch that kills power to the injectors or ignition system. ABS, electric power steering, airbags, cooling fans and everything else electric is unaffected. Hybrids these days do this all automatically, and more and more non-hybrids are starting to use start/stop systems to save fuel. My techniques are no different other than there isn't a computer controlling them.

    I personally don't do this so much to penny pinch. I own fuel efficient cars that are efficient to start with, however this does increase fuel economy even farther. Mainly, I find it quite fun to drive this way, and I enjoy trying to beat my own high score. So, it becomes a sort of game. The additional fuel savings is a nice perk I admit. Driving normally is boring IMO. Driving aggressively can be fun, and I do enjoy this aspect of driving as well from time to time (usually on my motorcycle). But, it also can become frustrating quickly as traffic gets in the way.

    I'm not sure why this riles people up so much except that they don't understand what is actually going on and assume the worst. If you don't like this way of driving don't do it lol. You're not gonna ruffle my feathers, and I'm not making anyone drive a certain way. I'm simply explaining how I do it and how you can save fuel. So, I hope that clears up some of the misconceptions and questions, but feel free to ask away if there are more.

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra SR automatic: 7.0 L/100 km ... 40.4 mpg (Imp) ... 14.3 km/L ... 33.6 mpg (US) ...


  8. #27
    Senior Member Micra In The Mountains's Avatar
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    I usually go by the 10-20 second rule, especially if going thru the drive-thru. I turn off the engine in traffic only as long as it is safe to do so, depending on traffic conditions


    Nice!

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