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Old 16th February 2007, 20:59   #16
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A minute isn't a long time if you really see the long term benefits. This sticker is also on the TCIC engined Safaris as well. As the turbo revvs at a very high speed, this one minute act is suggested after starting to lubricate all components of the turbo and before shutting off is for allowing the turbo to cool down & allow the oil to return back.

Answer for your second query - yes, I very diligently practice this.

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Originally Posted by prabuddhadg View Post
I read a sticker on the dashboard of a Scorpio, saying "Turbo charged engine. Run at idle for a minute after starting and before shutting off engine. "
Isn't a minute a looong time? Does anyone really do that?
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Old 16th February 2007, 21:53   #17
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So, what do we conclude from all the above observations ? Can we have it as a thumb rule that before switching off the ignition we let the engine idle for about a minute (w/o revving) and then shut it off ?
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Old 16th February 2007, 22:04   #18
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Yes! Letting the engine idle for 15-30 seconds before shut-off is recommended, though not completely necessary in modern, non-turbo cars.

Revving the engine before shut-off is the dumbest thing one can do and will put excess strain on it. (sorry if I hurt anyone there). Those of you with electrical problems forcing you to do this should look into them, rather than hoping that the extra revs will boost your battery or something.

As far as turbo nitty-gritties go, I'm pretty ignorant....however, in some aftermarket turbo setups that I've seen, an electronic turbo timer can be added that will actually keep the engine running (after u've shutdown and got out of the car) for a while to let the turbo stop spinning and cool down. Pretty handy....
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Old 16th February 2007, 22:15   #19
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While you original query was on how to switch off the car engine, certain posts digressed to switiching off the turbo diesel engines. What is good for the goose may not be for the gander (it is not sidhuism).

Hence the practice reccommended/adopted for turbo diesels need not necessarily be true for the petrols. Coming back to your post, one of the reasons that I heard long time back about revving the engine before shutting off, apart from topping the battery strength was that it left unburnt petrol in the chamber, thus enabling it to start the first thing in the morning. Now this was the time when all engines had carbs.

While this practice does not hold water, then & now, simply because any unburnt petrol in the chamber would have evaporated anyhow due to the raised temperature inside. So, it would not have made any difference to the starting procedure in the morning.

My conclusion is that you can't have a thumb rule for how to start & switch off coz it would vary for engines based on the kind of fuel they use. Basically, if the engine is well tuned & maintained and all other parameters like battery being good etc, remaining same this is not a major issue or of concern. Practising what manufacturer reccommends is the best..!

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Originally Posted by rr_zen View Post
So, what do we conclude from all the above observations ? Can we have it as a thumb rule that before switching off the ignition we let the engine idle for about a minute (w/o revving) and then shut it off ?
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Old 16th February 2007, 22:20   #20
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This turbo timer comes only for a very limited makes of turbo diesel cars - read imported technolgy being built in India. Example: Skoda, Toyota, Fiat etc. This turbo timer is not available for Indian built models: Safari, Indica, Scorpio etc..

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Originally Posted by vezj420 View Post
As far as turbo nitty-gritties go, I'm pretty ignorant....however, in some aftermarket turbo setups that I've seen, an electronic turbo timer can be added that will actually keep the engine running (after u've shutdown and got out of the car) for a while to let the turbo stop spinning and cool down. Pretty handy....
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Old 16th February 2007, 23:05   #21
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i was advised to stop for a min before i switch off the engine to take care of the turbo,in my verna.in old cars it was done for the battery and the oil circulation.ram
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Old 16th February 2007, 23:59   #22
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As far as I know in present cars it would only lead to charging the battery if revved ior left idle since the fuel air mixture being electronically controlled is automatically made rich when the sensor detects a cold start.as far turbocharging is concerned gd you wer absolutely right quting from wikipedia
"Turbochargers can be damaged by dirty or ineffective oil, and most manufacturers recommend more frequent oil changes for turbocharged engines; many owners and some companies recommend using synthetic oils, which tend to flow more readily when cold and do not break down as quickly as conventional oils. Because the turbocharger can get hot when running, many recommend letting the engine idle for one to three minutes before shutting the engine if the turbocharger was used shortly before stopping (most manufacturers specify a 10-second period of idling before switching off to ensure the turbocharger is running at its idle speed to prevent damage to the bearings when the oil supply is cut off). This lets the turbo rotating assembly cool from the lower exhaust gas temperatures, and ensures that oil is supplied to the turbocharger while the turbine housing and exhaust manifold are still very hot; otherwise coking of the lubricating oil trapped in the unit may occur when the heat soaks into the bearings, causing rapid bearing wear and failure when the car is restarted. Even small particles of burnt oil will accumulate and lead to choking the oil supply and failure. This problem is less pronounced in diesel engines, due to the lower exhaust temperatures and generally slower engine speeds."
" At the same time the lubricating oil from the engine is able to circulate properly so the turbine won't burn the lubricating oil that would otherwise be trapped within the charger with the turbine rotating at high speed. With regard to modern automotive turbochargers, the need for a turbo timer can be eliminated by simply insuring the car does not produce any 'boost' (during driving) for several minutes prior to the ignition being shut off."
Sourcehttp://en.wikipedia.org/wiki/Category:Turbochargers
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Old 17th February 2007, 20:56   #23
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A little off-topic:
Don't know about idling at shutdown, but you should definitely idle for a few seconds after startup, esp. when the engine is cold. And, this applies to all cars - Petrol/Diesel/Turbo/Carb/MPFI, etc. This is because, when the engine is cold, condensed petrol/diesel droplets go into the engine rather than the vapor, and burning efficiency is very very poor. Hence, lots of noxious gases like NO3, SO3 and what not are released. If you drive like that, the engine would feel powerless and burn even more gas. The harmful gases, which form acids when mixed with the water vapor, will corrode the insides of your engine. Result - low power, poor FE, poor engine life, lots of pollution.

Once the engine warms up, NO2 and SO2 gases are released, which also form acids that are much milder. Moreover, there's very little water vapor available to form the acids, and the gases are swept away to the exhaust.
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Old 17th February 2007, 21:22   #24
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Quote:
Originally Posted by amu1983 View Post
A little off-topic:
Don't know about idling at shutdown, but you should definitely idle for a few seconds after startup, esp. when the engine is cold. And, this applies to all cars - Petrol/Diesel/Turbo/Carb/MPFI, etc. This is because, when the engine is cold, condensed petrol/diesel droplets go into the engine rather than the vapor, and burning efficiency is very very poor. Hence, lots of noxious gases like NO3, SO3 and what not are released. If you drive like that, the engine would feel powerless and burn even more gas. The harmful gases, which form acids when mixed with the water vapor, will corrode the insides of your engine. Result - low power, poor FE, poor engine life, lots of pollution.

Once the engine warms up, NO2 and SO2 gases are released, which also form acids that are much milder. Moreover, there's very little water vapor available to form the acids, and the gases are swept away to the exhaust.
FIAT recommends driving away gentle after a cold start albeit not much acceleration and hard drive for initial couple of kilometers.

Coming back to the rational, How will idling help ? Infact cold start releases more dangerous emissions than a warmed up engine does. It is better not to idle upon a cold start if the car is in closed parking or in residential areas.
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Old 17th February 2007, 22:30   #25
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Quote:
Originally Posted by rr_zen View Post
I have observed a lot of drivers (cars and other four wheelers too) rev up the engine a bit before turning the ignition off.

I have asked this to one of our old age mechanic who used to do old age 'diesel' cars like ambys, fiats, jeeps, tempos etc etc... according to him, this helps the system in two ways... (1) the revving up will load the fuel lines with more fuel (than normal) which will ease up the next start. This is mostly done on the diesel vehicles which had that "pull" type engine killer switch!! (2) In those days, as the service of battery is supposed to be for 'life time' of the vehicle... everyone were extra sensitive on keeping the battery charged fully for the next start.

Felt the reasons pretty sensible to me!!! What say?!!
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Old 19th February 2007, 12:58   #26
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I usually do the following -
- bring the car to a halt, put it in neutral
- put on the handbrake
- turn out the headlights and/or foglamps
- remove the faceplate of my audio head-unit, place it in the glovebox
- wind up all windows
- take all my stuff
.. and then I switch off the engine. These activities typically take upto 30-40 seconds to complete. Come to think of it, I never actually thought of doing this for any particular reason. Somehow, it comes naturally to me. I'm glad to learn that it actually benefits my ride.
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Old 19th February 2007, 14:03   #27
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Quote:
Originally Posted by etchemkay View Post
I usually do the following -
- bring the car to a halt, put it in neutral
- put on the handbrake
- turn out the headlights and/or foglamps
- remove the faceplate of my audio head-unit, place it in the glovebox
- wind up all windows
- take all my stuff
.. and then I switch off the engine. These activities typically take upto 30-40 seconds to complete. Come to think of it, I never actually thought of doing this for any particular reason. Somehow, it comes naturally to me. I'm glad to learn that it actually benefits my ride.
Add to that the time I take for noting in my diary the names of main places I visited and the kilometres covered during the trip, and you have about a minute which is what I take.
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Old 19th February 2007, 14:04   #28
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Don't know about diesel cars, but definitely not required for a petrol engine - seen this only with old Amby/PremierPadmini types. If it were important, it would find a mention in the owner's manual - never seen it for our cars.
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Old 1st May 2007, 23:15   #29
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Quote:
Add to that the time I take for noting in my diary the names of main places I visited and the kilometres covered during the trip
Just wondering, why u do that ?
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Old 18th January 2008, 13:04   #30
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Quote:
Originally Posted by prabuddhadg View Post
Add to that the time I take for noting in my diary the names of main places I visited and the kilometres covered during the trip, and you have about a minute which is what I take.
Quote:
Originally Posted by austere_sly View Post
Just wondering, why u do that ?
Interesting that you have the patience. Lot of stuff to read for when you retire eh
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