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Old 8th December 2010, 15:58   #16
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Default Re: How much of fuel is used up during idle?

In cars the basic thumb rule is 3 minutes of idling is equal to the 1km of drive. Thats something i have seen recommended in high end cars manual by manufacturers.
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Old 8th December 2010, 16:15   #17
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Default Re: How much of fuel is used up during idle?

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Originally Posted by prajwalkashyap View Post
but in motorcycles, I have been able to extract maximum mileage just by equating the amount of fuel consumed to thumb-start the engine = 5 seconds of idling at 1100 rpm.
Do you mean to say we save more fuel by switching off and then on at a 10 sec signal? I was always under the impression that switching off is beneficial only if the signal is >30 seconds!!
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Old 8th December 2010, 16:31   #18
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Default Re: How much of fuel is used up during idle?

My Skoda Laura Diesel burns from 0.6 to 0.9 litres/hour, the max figure is with AC used on full blast. All figures from MFD.
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Old 8th December 2010, 17:11   #19
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Default Re: How much of fuel is used up during idle?

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Originally Posted by mondymk3 View Post
In cars the basic thumb rule is 3 minutes of idling is equal to the 1km of drive. Thats something i have seen recommended in high end cars manual by manufacturers.
This thumb rule makes some sense.

Can someone confirm from a Manual or some other source if this approximation is approximately correct
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Old 8th December 2010, 17:31   #20
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Default Re: How much of fuel is used up during idle?

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Originally Posted by kavesh55 View Post
I personally used to keep the idling speed close to 750 rpm...
How do you personally control the idle speed of engine close to 750 RPM?
I have never seen any car with 750 RPM. IMHO it is actually around 900 RPM.
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Old 9th December 2010, 21:18   #21
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Default Re: How much of fuel is used up during idle?

Thanks all for your replies.

After a long trip,I kept my palio home with fuel needle just hovering around the red mark.
In indica xeta,when the fuel indicator touches red,it still has around 5-7lts left in it.I thought its same case with palio also.

Due to heavy rain.I did not take my car out for more than 2 weeks.
I use to idle it for 5-10mts every 4 or 5 days.

Shell petrol bunk is just 4kms away from my home, Even if the car gives a mileage of 5km/ltr still i can reach it comfortably.
But to my horror,it has exhausted all the fuel within 3kms of running.
Still wondering how i managed to exhaust all those 5ltrs during idling.

Any pointers?
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Old 9th December 2010, 23:09   #22
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Default Re: How much of fuel is used up during idle?

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Originally Posted by rock18 View Post
Thanks all for your replies.

After a long trip,I kept my palio home with fuel needle just hovering around the red mark.
In indica xeta,when the fuel indicator touches red,it still has around 5-7lts left in it.I thought its same case with palio also.

Due to heavy rain.I did not take my car out for more than 2 weeks.
I use to idle it for 5-10mts every 4 or 5 days.

Shell petrol bunk is just 4kms away from my home, Even if the car gives a mileage of 5km/ltr still i can reach it comfortably.
But to my horror,it has exhausted all the fuel within 3kms of running.
Still wondering how i managed to exhaust all those 5ltrs during idling.

Any pointers?
Check what is the amount of fuel left when the guage hits reserve.. also, when the needle hits red, it doesn't necessarily mean you have the enter reserva quota of fuel left.

Another thing, the car must've burnt quite some fuel each time you started it; and considering there was heavy rain, probably some more to get the engine to optimum temp.

I doubt the car can exhaust fuel till the last drop. There must be some cut-off after which the fuel supply shuts off.
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Old 9th December 2010, 23:52   #23
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Default Re: How much of fuel is used up during idle?

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Originally Posted by libranof1987 View Post
]Also read this : "the FE reduces during idling because the engine heats up as there is no air in the opposite direction as is when it is travelling"..
There is no fuel efficiency when stationery.

When we say fuel "efficiency" we really mean fuel consumption, the amount of fuel it takes to move the car a certain distance (or, as we usually put it, the distance a car will move for 1 ltr of fuel). When the car is not moving, this is meaningless! 0km/ltr, always!
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Old 10th December 2010, 02:11   #24
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Default Re: How much of fuel is used up during idle?

Quote:
Originally Posted by Thad E Ginathom View Post
There is no fuel efficiency when stationery.

When we say fuel "efficiency" we really mean fuel consumption, the amount of fuel it takes to move the car a certain distance (or, as we usually put it, the distance a car will move for 1 ltr of fuel). When the car is not moving, this is meaningless! 0km/ltr, always!

Fuel Efficiency doesn't necessarily mean km/ltr. Car being a locomotive, we translate the efficiency figures into Kms.

The fuel efficiency of an engine can be measured in many ways. kms/ltr, hrs/ltr, W/ltr or whatever is the purpose of that engine.

Quote:
Also read this : "the FE reduces during idling because the engine heats up as there is no air in the opposite direction as is when it is travelling"..
I believe, the author must have meant, the overall efficiency of that engine.
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Old 10th December 2010, 03:37   #25
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Default Re: idling fuel consumption and pollution

Please check & continue the discussion on one of the following threads

Link 1 (Cars idling at crossings burn Rs 1,000cr a year in Delhi)

10 Engine Idling 'Did You Know' (10 Engine Idling "did you knows" EDIT: Myths & Facts added!)

Thread Closed
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Old 28th September 2011, 12:29   #26
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Question How does idling affect your fuel (Petrol and Diesel) consumption

Folks,

Can anybody tell me at idling what is the consumption of diesel and petrol.

As you all know most of our cities even if we drive less than 10 kms a day, the amount of idling we do is humongous.

Needs inputs on following

1. How much fuel or money we lose while idling and especially is there a major difference in fuel / money lost for a petrol or diesel

2. In cities, there are massive traffic jams that you face every day, does it make sense to include idling as a parameter when you calculate while choosing a diesel or petrol vehicle. How do we calculate that?

Post on.

Cheers
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Old 28th September 2011, 12:39   #27
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Default Re: How does idling affect your fuel (Petrol and Diesel) consumption

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Originally Posted by sahakar View Post
Folks,

Can anybody tell me at idling what is the consumption of diesel and petrol.

As you all know most of our cities even if we drive less than 10 kms a day, the amount of idling we do is humongous.

Needs inputs on following

1. How much fuel or money we lose while idling and especially is there a major difference in fuel / money lost for a petrol or diesel

2. In cities, there are massive traffic jams that you face every day, does it make sense to include idling as a parameter when you calculate while choosing a diesel or petrol vehicle. How do we calculate that?

Post on.

Cheers
Most cars idle aroung 900 - 1100 RPM mark. Unless you know the precise amount of fuel that the car is taking in, this will be difficult to say.

Also, from my discussions with a person from the industry (the company manufacturing the highest number of engines sold in India today), the ECU is designed to reduce the fuel fraction intake at idling speeds, which will improve efficiency. So sometimes, after prolonged idling, you will have a slightly higher lag when moving from standstill.
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Old 28th September 2011, 13:29   #28
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Default Re: How does idling affect your fuel (Petrol and Diesel) consumption

In Fabia TDI, the real time fuel consumption calculator shows 0.3L/Hr being consumed on idling (without AC) and between 0.7-1L/Hr with AC
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Old 28th September 2011, 14:28   #29
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Default Re: How does idling affect your fuel (Petrol and Diesel) consumption

Quote:
Originally Posted by ragzv View Post
In Fabia TDI, the real time fuel consumption calculator shows 0.3L/Hr being consumed on idling (without AC) and between 0.7-1L/Hr with AC
So that would mean for any similar diesel hatchback of Fabia's size, half an hour of traffic jam (which is most of us would face during rush hour) would cost half a liter of diesel everyday.

So around 10 liters a month and approx 100 liters a year.

Straight monetary difference between petrol and diesel would be savings of around 2200 Rs on a diesel.

Now if somehow we can find out, whether a diesel consumes less or more fuel than a petrol engine while idling.

Cheers
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Old 28th September 2011, 14:35   #30
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Default Re: How does idling affect your fuel (Petrol and Diesel) consumption

I have done an actual test on my Alto on the idling thing. I always calculate FE by the tank full-to-tank full method.

I once checked if there is any difference when I switch of the engine during traffic halts of more than 60 seconds. The comparison is over 2 tank-fulls; which means an average of around 450 kms of driving all within city.

I found that when I switch off the engine the FE actually went down by about 1km to the litre. I got an FE of around 14 if I did not switch off and an FE of 12.9 when I started switching off.

I have started to believe that I waste more fuel by switching off.
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