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Old 29th January 2013, 08:28   #16
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

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Originally Posted by SDP View Post
So for turbo-charged engines, one should wait for 30-60 seconds after stopping at a signal before thinking about turning off the engine.
XUV comes with the start/stop option, where the engine switches itself off at thse signal. Does this mean, we should disable this function, to extend the longevity of the turbo? Or is there some fuzzy logic on the electronics, that takes care of this idling time ?
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Old 29th January 2013, 08:28   #17
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Smile Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

GTO, as usual thanks a ton for the wonderful insight to the turbo charged engines.

However irritated I used to get listening to the previous gen diesel engines still I used to idle my friend's Indica for about a minute or so before shutting it off. I am surprised as to why the car manufacturers havent thought about automating this simple technique - Have some kind of a timer to allow the clutch/gear/accelerator to be used only after a minute of starting and dont allow the engine to shutoff unless idled for a minute.

Does the coking have an effect on turbo charged petrol engines too?
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Old 29th January 2013, 08:36   #18
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I am surprised to learn this. I did not spot anything in my Superb's owner's manual asking me to idle the car after shut down. Wonder if it is automated, since the cooling fan usually continues running for almost a minute after I come to a halt and switch the engine off (usually leads parking attendants to call me back).
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Old 29th January 2013, 08:43   #19
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

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Originally Posted by Hayek View Post
I am surprised to learn this. I did not spot anything in my Superb's owner's manual asking me to idle the car after shut down. Wonder if it is automated, since the cooling fan usually continues running for almost a minute after I come to a halt and switch the engine off (usually leads parking attendants to call me back).
Hayek sir, I believe the point is about having enough lubrication for the turbo rather than cooling down the turbo. The lubrication is dependent on whether the engine is running.
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Old 29th January 2013, 08:55   #20
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Just checked the manual. It specifically tells you to start and drive right away without idling the engine, but to idle for 2 minutes before switching off if the engine has been operated at high loads for a long period of time. What is the definition of high loads - is it only high RPM, or would Bombay style stop and go traffic also be a high load? It also says do not idle in a closed area, which is an issue since I park in a closed parking.
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Old 29th January 2013, 09:14   #21
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

Thanks for sharing this very insightful post GTO.

I religiously follow the idling rule on our Swift D. I idle for at least 30 seconds during each start up and ride the torque and keep the revs under 2000 till the temp needle hits the standard level. Thank God for that analog temp needle.

For stops, I keep the RPM low towards the end and stick to the 30 seconds idling. During highway trips, when the speeds are high, I keep it On for 1 min after pulling over.
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Old 29th January 2013, 09:27   #22
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

This is something which I have been following diligently. Everytime I am about to reach office, I slow down and reduce the revs. After any hard drive, I again idle the motor.

In case of my Altis, I don't idle before shutting off since it's not a turbo but on a cold start I idle for a minute, drive at low revs for 10mins till the temp needle rises to stable value then drive normally.

It's now embedded. Manson and Rehaan will agree with me
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Old 29th January 2013, 09:37   #23
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

Question:-

How do cars equipped with start/stop technology ( the technology when the car shuts off when you press the brake and comes to a stop & starts when the accelerator is pressed) .. like the latest BMW 3 series , deal with the one minute idling requirement for the turbos?

I'm pretty sure in the 328xi i drove the car shut off much earlier than a min. And I believe the 328xi is a 4 cyl turbo.
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Old 29th January 2013, 10:34   #24
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

Thanks a ton for compiling this wonderful insightful article. Maybe it should be tagged with Article as well.

There are different turbo technologies so there will be variations.

Generally till date most of vehicles have been sporting single turbos which operate and functional at higher rpms for highway speed runs. It is mostly then that the turbo cooling will primarily come into effect in such vehicles.

There has been influx of VVT and CVT variable turbos which operate and function at both lower and higher rpms for which this will start becoming binding to follow some strict rules in idling.

Also, the cooling techniques too have become pretty advanced in todays turbos having liquid cooled bearings which will help them bear the brunt of not idling. But inspite of that I wonder whether it is worthwhile to drop the idea of idling completely.

STILL, inspite of all the variations in turbos and their operating and cooling techniques, it does not hurt to do some minimal preventive action to idle pre/post drive absolutely. As Rehaan and SDP rightly mentioned above, the last leg of the journey can be sedate drive letting the turbo cool its heels but not necessary a killer for idling process.

But Start/Stop function is always going to put this into contention and which is where people will start wondering whether the Start/Stop function to be used or bother about the turbo idling. I remember, there was a small discussion on this on SDP's cheetah thread.

What I think, the Start/Stop function is meant and will come into action mostly in stop/go city traffic where the turbo is not going to be revved too high to need its heels cooled before one shuts off engine at a junction signal. The turbo has to be designed in way to bear this much load atleast in such cases. I would most probably use Start/Stop function in the city traffic but turn it off in highway runs.

Last edited by parsh : 29th January 2013 at 10:36.
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Old 29th January 2013, 10:44   #25
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

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Originally Posted by thoma View Post
Could you please mention the regular maintenance schedule / itinerary for a turbo-charger and its related parts too.
Just stick to the maintenance schedule of your owner's manual.

Quote:
Originally Posted by SDP View Post
Turbos are precision engineered and are VERY costly in comparison with other parts of the car.
You can say that again. A turbo repair / replacement build can run as expensive as an engine overhaul / replacement!

Quote:
Originally Posted by Biraj View Post
Ever since I got the T-jet, I have been trying to follow this rule religiously.
It's the turbo that makes the T-jet the special car it is . Please take good care of it.

Quote:
Originally Posted by subratasenn View Post
I must change this habit. I hope at 7500 km on my ODO it's not to late to begin!
Never too late, buddy.

Quote:
Originally Posted by soonya View Post
However on another thread where I read that it is recommended to switch off engines at the traffic lights to save fuel.
Switch the engine off only if your turbo has had sufficient time to cool down. And don't revv the minute you start her up again! I personally wouldn't switch a turbo-engine off at traffic lights.

Quote:
Originally Posted by amolpol View Post
A noob question - would basement parking allow for suitable time to cool down the turbo and keep it lubricated? Typically one has to stop and reverse their car in the tight spots which is done at idling rpms.
Drive at low rpm for the final kms and you should be okay with 30 seconds of idling. But the worst thing you can do is high-revv your diesel into your basement and then switch it off immediately.

Quote:
Originally Posted by Mudhalaipatti View Post
XUV comes with the start/stop option, where the engine switches itself off at thse signal. Does this mean, we should disable this function, to extend the longevity of the turbo?
The start / stop function kicks in only after a couple of seconds, right? That should allow the turbo to cool down a bit. I believe you can set the start-stop timer too? Take it to 30 - 45 seconds.

But of course, there isn't a doubt that the start-stop system puts additional stress on the turbo, starter & battery. In my 4 days with the XUV500, I put the start/off system off.

Quote:
Originally Posted by Hayek View Post
I did not spot anything in my Superb's owner's manual asking me to idle the car after shut down.
As far as I know, the 1.8L TSI petrol has a water-cooled turbo. Still, as mentioned in the article, you should idle for a minimum of 30 seconds before and after a drive. Alternatively (second choice), keep the revvs really, really low at the start / end of a journey.

Quote:
since the cooling fan usually continues running for almost a minute after I come to a halt
The cooling fan does nothing for the turbo.

Quote:
Originally Posted by Hayek View Post
What is the definition of high loads - is it only high RPM, or would Bombay style stop and go traffic also be a high load?
High rpm.

Quote:
Originally Posted by Jomz View Post
like the latest BMW 3 series , deal with the one minute idling requirement for the turbos?
The BMWs use water-cooled turbos. Also, the start/stop system switches the engine off only after a couple of seconds (not immediately).
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Old 29th January 2013, 10:57   #26
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

This is a great article for the large number of car owners who drive a turbo-diesel (or, for that matter, a turbo petrol) but are not aware of the do's and don'ts of how to take care of the turbocharger. Thanks for the detailed explanation, GTO.

A couple of points:

1. Make sure that the engine oil is the right grade and quality, or better than, as recommended OE. And don't skimp on oil changes, since there is sludge buildup in diesel engine oils rather quickly, especially if the car runs in an urban stop-start-stop environment. Sludge is the stuff that settles around turbo bearings and oil seals, and forms the 'coke' (carbon) layer over a period of time. If your manufacturer recommends 15k km between changes, I'd say change at 10k km max.

2. After a hard run, when you stop and let the engine & turbo idle, don't do it when your car is positioned over tall dry grass. The almost red-hot turbo and the exhaust pipe can set the grass on fire without your knowing it.
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Old 29th January 2013, 10:58   #27
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

Great thread.

The Toyota Fortuner manual has some conflicting advise:
1. Don't idle before driving off
2. Normal city driving: no cooling off period required

Obviously it also says that one should cool for 1 min or 2 mins after high speed driving (depends on speed and for how long - it doesn't mention RPM, but has thresholds based on 80 kmph and >100kmph) - this is a must.

But why # 1 and #2? In fact it says that excessive idling can damage the engine.

I follow the 'slow down before reaching destination', 'don't rev/push a cold car' and 'idle for 2 minutes after high speed driving' diligently, but would like to get the 'no need to idle for normal/city driving' confusion sorted out for peace of mind :-)
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Old 29th January 2013, 10:59   #28
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

Thanks a ton, GTO. This is excellent information and an eye-opener for guys like me. All my life, i thought warming up at the time of start up is all that needs to be done. Never knew idling before switching off is so important. This is all the more important for me bacause i have never driven any turbocharged car till now but i am going to own one soon.

OT: @GTO, this thread can be one of the "Hot Threads" on home page.
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Old 29th January 2013, 11:21   #29
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

Excellent thread GTO

have doubts!

how effective the turbo timers are.any users here?

how will the central locking work with the turbo timer.once the car switches off wont it unlock the doors? assuming you leave the car idling with handbrake,lock the car and walk off.
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Old 29th January 2013, 12:11   #30
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Default Re: Why you must practice the "Idling Rule" with Turbo-Charged Cars

Thanks GTO for this informative thread.

Like in my car ( F30 with the N20 ) i see the start stop doesnt work when the engine is cool & starts to operate after reaching a minimum engine heat level.

But what after a high revving run if i approach the signal & the engine shuts down to save fuel would'nt it harm the turbo ?

Quote:
Originally Posted by GTO View Post
The BMWs use water-cooled turbos. Also, the start/stop system switches the engine off only after a couple of seconds (not immediately).
^ Does this mean couple of seconds are enough for water-cooled turbos ?

Last edited by karan561 : 29th January 2013 at 12:21.
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