4 cylinder mode

Discussion in 'Dodge Challenger General Discussions' started by Mfknjadagr8, Aug 15, 2020.

  1. Mfknjadagr8

    Mfknjadagr8 Full Access Member

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    I know its not really a great idea to idle a lot in our girls but when I'm at work I tend to sit in my car and enjoy the ac on lunch as its usually 100f+ inside where I work i like the cooldown. I wish there was a way to force the car into 4 cylinder mode when im going to sit for an extended period of time as it definitely doesn't need all 8 cylinders when idling for awhile... im assuming there is a reason this doesn't work this way but I cannot see it damaging anything if it were an option. Does anyone else think this would be a good option or know if its possible to do this or perhaps why it would be a bad thing? Open to all opinions on the matter :)

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  2. SRT-Tom

    SRT-Tom Well-Known Member Staff Member Super Moderator Article Writer

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    Besides wasting gas (allowing your car to idle for two minutes is equivalent of driving a mile), you should also consider these negative effects about prolonged idling:
    • It is bad for the environment. Your exhaust system produces emissions into the air and contributes to air pollution. Sitting in one spot for a long period of time pollutes air.
    • Decreases performance. Over time, idling can cause your head gasket,spark plugs, or cylinder rings to deteriorate and stop working.
    • Drains car battery. Idling does not allow your battery to charge and causes it to strain.
    • Burns up oil. Longer time leaving your engine running causes more motor oil to be circulated and burned up. This will cost you more money due to more frequent oil changes.
     
  3. Katshot

    Katshot Full Access Member

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    Gotta say, these points range from taking the obvious to extremes, to flat wrong.
    The answer to the question about whether you could utilize modulated displacement while idling is actually pretty simple. While some applications "could" actually continue running at idle while dropping cylinders, the engine wouldn't be running very well, let alone able to properly support normal accessory loads such as charging system and HVAC.
     
  4. Mfknjadagr8

    Mfknjadagr8 Full Access Member

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    Thanks Kat this is kinda what I was looking for. I was sort of under the impression it would likely be a rough idle and admittedly I didn't read up on exactly how the mds works prior to asking this was strictly from a gas savings standpoint. I will have to make more trips to the pump or forego my air conditioned outings at work....i would wager ive spent a full tank idling in the past 4 weeks but i did wait until 500 miles before I did any major idling....

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  5. Katshot

    Katshot Full Access Member

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    While idling is by no means a super efficient RPM for an engine, it's not like it's going to kill it. Modern engines are far more tolerant of varying operating conditions than older ones. I know many people who live only a couple miles from work and I can tell you that they are doing far more damage to their vehicles than you with such short duration runs.
     
  6. Mfknjadagr8

    Mfknjadagr8 Full Access Member

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    I only live few miles from work as well but its at 65 speeds and I usually up to operating temperature by the time I get to work so its not short cycling I guess. I was always told short cycling and not reaching full operating temperature was hard on everything in the motor due to everything not fully expanding before it contracts again. That and fluids not reaching optimum temperature for lubrication etc. Often if for whatever reason im not at operating temp for where I go I idle until I reach it before turning the car off just in case. I've never owned anything nice until now so I never really cared if I short cycled but its more of a question now that I'd like to take care of this one.

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  7. 70-426_10-SRT

    70-426_10-SRT B&E body lover

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    Crap, I have waited, STOPPED, Idling in PDX Traffic for more than 45 minutes.
     
  8. Golfnut

    Golfnut Active Member

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    What I have heard and read is the biggest culprit wanting to implode an engine are the number of cold starts. Cold starts tend to cause the engine to start working without the benefit of complete lubrication as oil has drained off the pistons/cylinders surfaces while not running. Using synthetic oils helps eliminate this problem as synthetic oil adheres to the surfaces better than dino oil. I am not an expert on this and am only repeating what I have read many times and seen talked about in car maintenance videos many times.
     
  9. Katshot

    Katshot Full Access Member

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    While cold starts are indeed a tougher operating condition than a warm (or hot) start, the engine is designed for it. In a perfect world, an engine would only operate in a nice cool (not cold) environment, be brought to about 3500rpm or so right after start, and remain there under a continuous light load. We all know that's just not realistic.
    Not sure what car (engine) you have but going by my 6.4, I can tell you that it is rather slow to warm up. That being the case, I'm likely to believe that short trips are especially tough on my car.
    Regarding this issue, you need to remember that just because your temp gauge shows the engine is up to temp, it doesn't mean you're OK. There's still a lot of moisture and petro impurities (including acids) in the oil and exhaust that needs to be boiled off, and that takes time. If this moisture etc doesn't get eliminated during each trip, you end up with a cumulative effect over time. You can adjust for this partially by increasing your oil change frequency but that only helps the engine. The exhaust will still suffer. Luckily, most new cars have largely stainless components in the exhaust so the effects of increased moisture is minimized.
    In the end, your driving habits and maintenance practices have everything to do with how your car will survive your ownership of it. Luckily, these cars are built to handle a great deal of abuse so it's not likely to fall apart on you if you're not operating it in the best possible way. That being said, you certainly can help the situation by being mindful of how your driving habits affect your car and making adjustments in your maintenance schedules to minimize the potential damage.
    In my mind? Drive the car however it makes you happy and keep up with maintenance. If it breaks, it breaks.
     
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