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Letting the engine idle for a bit before switching off

Discussion in 'A3/S3/Sportback (8P Chassis)' started by mikeyboy, Jun 16, 2013.

  1. mikeyboy
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    mikeyboy Member

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    I'm having a bit of a debate with my dad here, I always idle my engine for at least 30 seconds before switching it off or 2 mins if I've been planting my right foot on the throttle. The reason I do this is to keep the oil supply to the turbo while it slows down so it's not spinning without lubrication. My dad on the other hand reckons this is a load of ******** and is just a waste of diesel. So is it a good thing to do or not?
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  2. Gaz!
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    Gaz! Member

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    Very good thing, the turbo will still be running down after you switch off. Prolong it's life and keep the oil supply going to it.
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  3. phil76
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    phil76 Member

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    Tell your dad to keep to ironing
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  4. mikeyboy
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    mikeyboy Member

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    Yeah I thought so. So do you do the same?
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  5. mikeyboy
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    mikeyboy Member

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    lol nice one. So I was right after all
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  6. gogz s3
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    gogz s3 Active Member

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    Even though it's Fathers Day, he is wrong :arco:

    Always let it cool down and wait til engines up to temp before thrashing :yes:
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  7. wangdoodle
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    wangdoodle Member

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    I thought if you turn the engine off with a hot turbo then the heat soaks into the now sitting oil and of course the hot oil isn't carrying the heat away.
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  8. mikeyboy
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    mikeyboy Member

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    Yeah that's what I do. I never rev it past 2500 revs until the temperature gauge is at 90 degrees
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  9. sliced
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    sliced Drive safe, stay alive.

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    Doesn't matter too much tbh, thought there was some fan thing that comes on if the turbo was too hot when u turn the engine off
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  10. Minstadave
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    Minstadave Member

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    Whilst I can see the logic behind this do you have any evidence that this is the biggest cause of shortening a turbo's life?

    More and more turbo cars are being sold and I've never seen a manufacturer actually recommend this, and I'm sure the vast majority of people just switch off. If it really was that important surely this would be automated (electric oil pump that runs after ignition is cut).
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  11. mikeyboy
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    mikeyboy Member

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    but you still need the oil to lubricate the turbo as it's spinning
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  12. mikeyboy
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    mikeyboy Member

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    an electric oil pump would be a good idea
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  13. Chillout
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    Chillout Member

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    Running your engine for a few minutes at idle circulates oil an prevent caramelisation of the oil within many jap cars were retrofitted with turbo timers for this reason even when you remove the key and lock the car it would over run for bit
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  14. chinnyhill10
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    chinnyhill10 Member

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    That's only the water temp. If you go into the service menu on your dash you'll be able to see an oil temp readout. It's buried in with the service interval details.
    #14
  15. Patrick_c99
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    Patrick_c99 Member

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    How do you get into these details I've never found then?
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  16. mikeyboy
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    mikeyboy Member

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    I don't have full DIS mate
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  17. SPARTAN91
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    SPARTAN91 RED FIVE STANDING BY

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    Having the white DIS spec I,ve found the oil temp reading can you see that info on the red DIS spec
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  18. DJ-S3
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    DJ-S3 Member

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    My mates RX7 did that. It always worried me that someone could just smash your window and drive off!
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  19. Sevv
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    Sevv Pushing the limits..

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    i usually wait 5 minutes after driving the car... and tend to drive between 1.5 2 RPM 5 minutes before arriving to my destination
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  20. immo
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    immo Stop me

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    Do you actually sit in your car idling for 5 minutes after every journey? If so, WOW.
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  21. Lewbo
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    Lewbo Well-Known Member

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    What engine do you have mate on the 2.0 TFSI there's a secondary auxillary water pump that circulates coolant round the full system once the engine is turned off. This goes the opposite way round compared to when coolant flushing round when engine is running this helps protect engine turbo ect. Don't think diesels have one though.
    #21
  22. leeds2592
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    leeds2592 When I grow up, I want a 964!

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    ain-t-nobody-got-time-fo-dat-sweet-brown-31241125-480-330.jpg
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  23. bez101
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    bez101 Yorkshire & Humber Rep.

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    dont bother wasting your time leting the audi idle there modern cars they just dont need it
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  24. sliced
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    sliced Drive safe, stay alive.

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    i believe he does, forgive me if I'm wrong but I think he's the one that has or has had big turbo conversion so it makes sense lol
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  25. MartayMcFly
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    MartayMcFly Well-Known Member

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    You're better off easing off a bit before you park and letting the turbo cool down before turning the car off. I'm never sure what's an old wives tale and what's still best practice on modern cars/engine, but generally a bit of a rest before turning off is going to help prolong the life of the motor.
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  26. bootneck_max
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    bootneck_max Member

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    Unless your running a highly tuned turbo charged engine, it's a waste of time! The car manufacturers would specify this when you buy the car if there was any requirement to do so!! So stop wasting your life and just turn the bloody thing off!

    However I do agree when you have a highly tuned car! My rx7 was running 480bhp on single turbo....and would always cool this down, however it's a highly tuned performance engine.... The diesel in your a3 is not a performance engine, and the people at audi take into consideration when they design these engines that people will drive them hard then switch them off! ... Your not driving a race car... End of....
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  27. Sevv
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    Sevv Pushing the limits..

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    yes its me , i wait 5 minutes on a 2.0tfsi quattro.. i think it helps the engine .. oil cool down pressure goes down etc... even though they have an after run pump.. to me it dont matter... usually it doesnt need more then 2-3 minutes but my OCD kicks in....
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  28. mikeyboy
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    mikeyboy Member

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    Looks like we have a keyboard warrior here! What the **** has performance got to do with it? Regardless of what you drive if you turn a turbocharged car straight off (even after a short journey) the turbo will still be spinning with no oil supply! The whole point of letting it idle for a bit is to keep the oil supply to the turbo while it slows down to a halt. Think before you jump the gun and bang away at your keyboard mate.
    Last edited: Jun 21, 2013
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  29. Gaz!
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    Gaz! Member

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    Lol, spot on. Some people have no idea about engineering principals.
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  30. mikeyboy
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    mikeyboy Member

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    :icon_thumright:
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  31. s3reptdi
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    s3reptdi Member

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    Mikeyboy is 100% correct, I personally cant be bothered with it, if the turbo is going to go its going to go, then time for hybrid and remap
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  32. ShaunS3
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    ShaunS3 Yorkshire & Humber Rep.

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    It's what is commonly referred to as 'Mechanical Sympathy' and I've always believed in 'look after your car and your car will look after you'

    I always warm up and cool down my cars correctly, even more so with turbocharged cars.

    Warming up properly is vitally important as 95% of engine wear occurs within the first minute of your engine starting/running and it's important not to thrash it until the oil has warmed up and properly circulated.

    Cooling down is just as important with turbocharged cars as previously stated due to the oil feed still being there whilst the turbo is still spinning. This reduces wear to the turbocharger as the bearings are not running dry whilst still spinning after the engine has been shut off, which could ultimately result in premature failure. Something I don't want to encourage, especially after fitting a new hybrid turbo.

    Some car manufacturers do give guidelines for this, such as Subaru. Located on a sticker inside the door shut on some imprezas was something on the lines of "allow to idle for 1 minute after high speed driving"

    Either way, it's all based on personal preference and how much knowledge of engines you hold, how much mechanical sympathy you have for your own car. Personally, I prefer to warm up and cool down correctly to minimise engine wear....each to their own.

    Shaun.
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  33. kog
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    kog New Member

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    If you need to idle a turbo before you STOP the engine, then I see a BIG problem. Picture this, you are coming off a motorway, onto the slip road into a queue of traffic having been on a long run. You come to a stop and the STOP/START Technology in your car kicks in and stops your engine dead as it does. What happens to your turbo???
    Last edited: Jun 21, 2013
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  34. s3reptdi
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    s3reptdi Member

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    That is a good point, personally I think stop start is **** It has to do more harm than good
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  35. DJ-S3
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    DJ-S3 Member

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    Some times the stop start doesn't actually do it. I imagine that's because the turbo needs oil after being used hard. I'm probably wrong but it doesn't sound that far fetched.

    If you go on a track day then yeah, leaving it to idle for a few minutes sounds about right. But if you've been giving it some down country roads and then go into a 30zone (or 20 in my case, damn speed bumps!) surely the turbo stops spinning after 30seconds of poodling to your house or place of work...? In which case turning it straight off should be fine.

    Im not mechanic and I'm not saying that everything I've said should be believed but when your not using the turbo (ie coming to a stop) surely the turbo shouldn't be spinning? Just like to point out again, I'm not a mechanic and if I'm wrong (could be) I'm sure someone will put me in my place. Haha
    Last edited: Jun 21, 2013
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  36. s3reptdi
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    s3reptdi Member

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    The turbo is always spinning, it relies on exhaust gases
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  37. SPARTAN91
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    SPARTAN91 RED FIVE STANDING BY

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    Car manufactures don't bother wasting there time to tell car buyers things like this because most people only buy a car to get them from A to B and don't give a dam how it works or how to care for it so as long as the parts under warranty last the 3 years or so the manufactures don't care how you look after your car or how you drive it.
    Last edited: Jun 22, 2013
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  38. 964kevin
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    964kevin Member

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    it is good practice, and as an apprentice a few years ago it is how I was trained to do this, I did it on my old B4TDI whihc covered 255,000 with no problems what-so-ever, and I continue to do it on the 8P.

    it is mechanical sympathy. I believe my drivers book also says after a hard drive slow down for the last couple of miles, or similar....

    After all, does it do any harm? costs 2 mins of time....hey ho, life that short you can't afford this?

    K
    #38
  39. DJ-S3
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    DJ-S3 Member

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    And there we go. Thought I'd be wrong. Damn! Ha.
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  40. R34nel
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    R34nel Member

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    It does state that after driving under load to let the car idle for xx seconds before switching off, in many car handbooks, I haven't checked if it says that in the audi however.

    it's like people who hammer their car from cold.... So nieve
    #40

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