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Auto Start/stop worth it?

Discussion in 'Audi S4/A4/A4 Cab (B8 Chassis)' started by rosscotdi, Aug 1, 2010.

  1. rosscotdi
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    rosscotdi Member

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    We have had our 2.0tfsi for 1500 miles now and getting used to the start stop.
    Now i can understand it is usefull to switch off when waiting for a long set of traffic lights, traffic jam etc but what is the cut off point?
    All that power required to start the engine, fuel used to start the engine, electrical power used by the car whilst engine is off, that needs put back in the battery... Not to mention starter/solenoid/flywheel (other engine parts i dont know) wear+cost of replacement

    So the question... when is it worth the engine going off... if i know the traffic lights are changing soon should i keep the clutch in... or let the car do what it wants cause it knows best
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  2. scoTTy
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    scoTTy Active Member

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    I've heard different figures ranging from 7 secs to 35 secs.

    I don't let it (either clutch or button) turn off it we're gonna move within 20 secs or so....which is probably the worst of both worlds! ;)
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  3. hittchy
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    hittchy Member

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    I think the novelty wears off after a while. I tend to hit the button straight away now to disable it and haven't noticed any difference in fuel economy on my daily journey. I can see the point if you're often stuck in standstill traffic, but when this has happened to me the car has restarted after a minute of two anyway!

    It's caught me out a few times where I've tried to pull off too soon and the electronic handbrake hasn't released. This hasn't happened with stop-start disabled though.

    It's a valid point about extra wear and tear - I'd be a little concerned if I was buying a 3-4 year old car, but I guess it's the same for any new technology.
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  4. Crazyfool
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    Crazyfool Lead boot

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    I just leave it on and let it decide whether it wants to turn the engine off or not. As Hittchy says, if you are at the lights with the handbrake on and s/s, it takes longer to move off; but I think it is more to do with the brakes rather than the s/s system, although the delay is compounded by the combined system.

    What gets me is when the car restarts due to something making it vibrate or judder; such as a motorbike passing or closing the boot (whilst someone else is in the driving seat)
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  5. PetrolDave
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    PetrolDave Active Member

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    I had an A3 courtesy car with start/stop for several days and ended up turning it off. I got fed up of the aircon going off and the fan speed reducing, which resulted in me baking in the hot sun (this was about 3 weeks ago) while waiting at traffic lights.

    I read somewhere that it put hill hold on when it stopped the engine (which seems to agree with what hittchy has seen), so there's no need to manually put the handbrake on.

    The speed it restarted the engine on pressing the clutch was impressive though.
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  6. scoTTy
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    scoTTy Active Member

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    I thought the A/C wouldn't turn off. i.e. it's one of the conditions of Auto stop/start that the engine should continue if required to maintain the temp that's been set....isn't it?
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  7. hittchy
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    hittchy Member

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    I thought the same.... however, I have noticed that the fan speed sometimes reduces if the stop-start activates. I wonder if it maintains cabin temperature within a few degrees - once it goes above this limit the engine re-starts.
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  8. Crazyfool
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    Crazyfool Lead boot

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    I think it is. The garage told me that it will only activate once the car is happy with the inside and engine temparatures.
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  9. PetrolDave
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    PetrolDave Active Member

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    On the 2010 A3 loan car I had the auto Start/Stop still cut the engine off even though the inside of the car was really hot (well above the set temperature so the A/C was blowing hard), and when the engine cutoff the fan slowed right down and obviously ambient air was blown into the car. IMHO that's rubbish.

    If what you say is correct then I could be sold Start/Stop, but that's not how it worked on the loan car I had.
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  10. redspudder
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    redspudder Sparky

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    If the air con is on auto then stop/start only activates if cabin temp is at the set temp which is selected in this case then the fans would have stopped anyway.if the fans are on manual then stop/start will not activate at all are you sure the A3 stop/start activated?if so then it sounds like fault
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  11. PetrolDave
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    PetrolDave Active Member

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    Yes, absolutely 100% sure - it was pretty obvious when the engine stopped and the rev counter dropped to zero.:keule:

    If it was faulty then that's pretty poor for an Audi dealer loan car that had less than 3000 miles on the clock.

    Yes, the air con was on Auto.:thumbsup:

    What you say about how start/stop should work would be OK by me, but my only experience of an Audi with start/stop doesn't bear it out.
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  12. murran
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    murran Active Member

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    i really cant see the point. the shear idea of it seems like such a non idea.
    i mean a modern fsi engine injects the smallest of small amount of fuel at tickover.
    taking this into account against wear and tear of the engine starting up all the time, starter, flywheel wear. not to mention the oil pressure dropping when the engine stops, then it starting again and building up pressure after a second or two. all those seconds causes bearing wear.

    i wouldnt have it!
    Last edited: Aug 11, 2010
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  13. scoTTy
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    scoTTy Active Member

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    Then you won't get a new manual 2L (pertrol or diesel) A4 or in future many other cars. Like it or not it's becoming more common.

    I personally don't have any problems with it.
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  14. murran
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    murran Active Member

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    actually, my daily transport is a 28 year old bmw! so no, no danger there lol!
    i just work on these stupid, over complicated, awful cars everyday.....
    #14
  15. Crazyfool
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    Crazyfool Lead boot

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    Wasn't it BMW that introduced the stop/start system first...I could be wrong!
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  16. Mcgough
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    Mcgough Member

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    Ive got start/stop and it never works if aircon is on or above around 6 speed on fan, and its never lowered the speed to stop and never turned aircon off.

    But is very useful if you stall car like a plonker at roundabout or crossing because as soon as you dip clutch it restarts and you can be away in a jiffy before your face turns red.
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  17. Crazyfool
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    Crazyfool Lead boot

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    Agreed, I have been caught out a couple of times when I have had the revs too low and it just restarts the engine
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