Engine idling isn’t as good as we thought

How-To, Interesting | January 7th, 2015 by 27
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Moral of the story is: don’t idle when the car is cold, just drive it to warm it up

I hate winter. Okay, maybe I don’t hate it, but I’m definitely not a fan. I like the idea of winter, though. The picturesque winter you see in pictures of snowy treetops and frozen lakes.

Not New Jersey winter, which is usually just a slushy, cold mess that’s more aggravating than beautiful. That’s the winter I have to deal with. So when I start my car in the morning, I’ll usually go back inside while it warms up so I don’t have to sit in the cold while I wait. Apparently this isn’t the best idea.

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@Syed Hoda

 

I thought, like most people, that driving your car when the engine is ice cold was bad for it. It isn’t really anymore. That was true during the days of carburetors, as they wouldn’t work well when cold. But now that cars are fuel injected, this is no longer an issue. In fact, driving the car, albeit somewhat slowly, is the best way to warm the car up. It’s also the fastest way to get the heat working.

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I’m no Eco-Mentalist, but I can also agree that it isn’t best for the environment to be pumping out exhaust fumes longer than necessary. Especially when the engine is cold because catalytic converters need to warm up to work properly, so emissions aren’t the best when cold. This may not sound like the type of thing BMW enthusiasts care about, but there’s no sense in hurting the environment while idling. It’s way more fun to hurt the environment while driving fast.

Also, idling for more than ten seconds is actually less economical than restarting the car. It was always said that shutting the car down and then restarting it was bad for the engine, and worse on gas. Again, maybe during the carburetor times, but not so anymore. Especially with direct injected engines which are extremely efficient as the cars brain can figure out the exact amount of fuel necessary for any given moment.

So, the moral of the story is: don’t idle when the car is cold, just drive it to warm it up. However, a friendly word of advice, let the engine get up to operating temperature before really giving it the beans. I don’t like to rev my car past 3,000 rpm until it’s warmed up and my car’s made it to 237,000 miles and still runs beautifully.

So don’t idle, just take it easy until it’s warmed up, then punch it.

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27 responses to “Engine idling isn’t as good as we thought”

  1. Slawomir says:

    Sorry, but you are wrong. If your cars is covered with snow, you HAVE TO warm it up, to get clear windows.

    • Jean Val Jean says:

      Nooo, just drive off, the air rushing over the car at 40-50 will clear the snow off the windows. And most bmw drivers have no patience to wait for the ice to melt anyway… :/

    • John Greenstreet says:

      Last night my car was covered with snow over a layer of ice. But with a good scraper and brush I had it clean in under three minutes. During that time the car wouldn’t have warmed up by any significant extent.

    • orlandipo says:

      Idling the engine is one of the most inefficient ways to clear windows

  2. John Greenstreet says:

    In Germany, for pollution reasons, it’s actually illegal to just start your car and leave it sitting to warm it up. That’s why remote starters aren’t available from the factory for BMWs.

  3. Ilk says:

    Does this apply to diesel (common-rail diesel) engines?
    (sorry if the question is stupid)

  4. Ash says:

    sorry for this sill question – but how do you know when the engine has warmed up?

  5. […] article Engine idling isn’t as good as we thought appeared first on BMW […]

  6. BMWGuy says:

    What about the Oil. You have no protection while the oil is cold. you have to wait for xx temp before the oil is protecting the engine…

  7. BMWGuy says:

    What about the Oil. You have no protection while the oil is cold. you have to wait for xx temp before the oil is protecting the engine…

    • Horatiu B. says:

      Some say the synthetic oil is fine. I guess conflicting info. BMW techs said just drive up, don’t rev up past 2K RPM and it will be fine

    • Dereklsj says:

      This is correct. The oil needs to have some temperature to it. It doesn’t take long, maybe 30 seconds to insure all the components that have basically gone dry overnight, or longer, have the proper lubrication and film on them. This was mentioned to me by a BMW engine builder, especially with four overhead cams.

    • Dereklsj says:

      This is correct. The oil needs to have some temperature to it. It doesn’t take long, maybe 30 seconds to insure all the components that have basically gone dry overnight, or longer, have the proper lubrication and film on them. This was mentioned to me by a BMW engine builder, especially with four overhead cams.

  8. […] Read the original … Engine idling isn’t as good as we thought […]

  9. Dereklsj says:

    I agree for the most part about not idling for more than 10 seconds. I disagree slightly when it’s sub freezing. With four overhead cams, there’s a lot of surfaces that are critical to having all the right oil pressures and lubricity, if it’s been sitting overnight, or longer. In these cases I idle for 30 seconds, then drive.

    • Horatiu B. says:

      So I guess a balance…lots of people today are idling the car for 15 min

      • Dereklsj says:

        I think 15 minutes is way overkill and isn’t the best for your engine. 2-3 minutes if you want to idle it for an “extended” time, should be plenty. After that, it should be driven to completely warm it up. Long term idling can create problems in the combustion chamber. For one, all the gas that enters the chamber isn’t completely burned and creates carbon issues during long idles.

      • Dereklsj says:

        I think 15 minutes is way overkill and isn’t the best for your engine. 2-3 minutes if you want to idle it for an “extended” time, should be plenty. After that, it should be driven to completely warm it up. Long term idling can create problems in the combustion chamber. For one, all the gas that enters the chamber isn’t completely burned and creates carbon issues during long idles.

    • Horatiu B. says:

      So I guess a balance…lots of people today are idling the car for 15 min

  10. Dereklsj says:

    I agree for the most part about not idling for more than 10 seconds. I disagree slightly when it’s sub freezing. With four overhead cams, there’s a lot of surfaces that are critical to having all the right oil pressures and lubricity, if it’s been sitting overnight, or longer. In these cases I idle for 30 seconds, then drive.

  11. Edwin says:

    Article? What article? I can’t stop drooling over that 1M.

  12. Billy Sánchez Olivares says:

    It’s not just about the injection it’s about the right temperatura of the metals in the engine and the temperatura of the oil engine.
    Also, since I love my Ultimate Driving Machine and I do Cheer The Driuving Pleasure, I do understand the risks for the enviroment when driving and reving up my BMW with cold engine.
    As long as we don’t see a real fact about this, I’m still warming my car for at least 5 minutes before driving it properly.

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