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Old 25th February 2007, 13:34   #1
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Default Idling at signals,traffic jams

There have been threads regarding fuel consumption at signals and things like that, but I did not get whether we should let the engine idle at signals or turn off the engine in terms of damage to the engine.
In cities like pune the signals are not synchronized in many places and you keep getting a red at every intersection once you get a red at any intersection.This results in frequent switching on and off the engine.Also my driver keeps switching off/on the engine even in traffic jams.

Kindly advice if chances of damage to the engine are too large to offset gains in fuel saved.
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Old 25th February 2007, 13:41   #2
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Thumb rule - if the stoppage is for more than 30 secs, engine should be switched off.
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Old 25th February 2007, 13:48   #3
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Lets take two intersections maybe not that far apart,after switching on/off the engine at this signal,i reach the second intersection and find a red there too,now should i apply the 30 second rule here too.
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Old 25th February 2007, 14:45   #4
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This thumb rule applies to distinct stop/start situations and not where one set of stop/start seamlessly merges with another. In which case its better going on horseback anyway.

Nothing prevents a car from being switched off/on frequently except for the prospect of a blown starter.
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Old 25th February 2007, 17:17   #5
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most traffic signals here have a wait time of over 120secs...usually we dont put the car off..the car idles with the a/c on or off...even in traffic jams..the car is kept on...unless your the first one at the signal and its over the above mentioned time then it is wise to switch off.
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Old 25th February 2007, 17:36   #6
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but while idling for a car that gives around 12 km/l what would be the fuel consumption per min while idling(with ac off)


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Old 26th February 2007, 01:05   #7
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multiply the time i mean if u get 12kmpl at 4000rpm and if it takes 40 seconds for a km so 4 X 40 160 seconds
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Old 28th February 2007, 16:53   #8
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As per Maruti website, idling for a minute is equivalent to 1 km ride (doesn't say whether a highway ride or city), so if you idle for 12 mins, you'll burn out 1 litre of fuel.

Actually, I don't agree with the 1st statement. Let's say you put the car in 5th gear, and the road is leveled, and silk smooth, and your rpms are very modest (almost like idling), your speed would then be close to 50 kmph, which covers 0.833 km per min. So, if your car gives 12 kmpl, your idle time for 1 litre is 14 mins, not 12.
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Old 28th February 2007, 17:07   #9
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I am not sure if this would apply for turbo charged Engines as the manufacturer recommends that the Engine is allowed to idle for a minute after every start.
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Old 28th February 2007, 17:38   #10
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Hmm, I switch off only when its close to 90 or 100 seconds or so. Not the right thing, it seems like from this thread..
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Old 1st March 2007, 01:16   #11
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I switch off when it's more than 60 secs and am not the 1st one in the que. The thread seems to talk about 30 secs.....isn't that amount of fuel be spent in restarting the car.

Let's hear the biggies.
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Old 1st March 2007, 01:38   #12
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i just wanted to know how much fuel is used while idling. i NEVER turn my car off even if its close to 120 seconds cause i need my car on for my ICE to run smoothly.
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Old 1st March 2007, 02:36   #13
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Quote:
Originally Posted by paras211 View Post
multiply the time i mean if u get 12kmpl at 4000rpm and if it takes 40 seconds for a km so 4 X 40 160 seconds
Arrey ...How come? Consider factors like while car is running engine has a load of its body weight, passengers, Wind thrust etc..etc. While engine is idling its virtually load less. So it will consume proportionately far less fuel.
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Old 3rd March 2007, 00:15   #14
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Easiest way to find out? Drain your gas tank completely, add a litre of fuel to it post that & then time it to see how long before it runs out.
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Old 3rd March 2007, 07:16   #15
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I never switch off the engine at traffic lights, jams etc. The A/C is always on in my car.
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