New SL350 and kickdown lag

InsideInsurance

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I have bought my first Mercedes and my first auto in the form of an SL350 (2013). Generally its all good after the first few user errors were sorted out but unfortunately my local MB garage has gave me wrong advice on all of these so far (eg the automatic application of the parking break if car is turned off in Hold, they claimed this didnt happen and the manual was wrong) so I hoped that you guys may be more knowledgeable.

The one outstanding thing, if I "floor it", and go through the first point of resistance on the accelerator the rev counter immediately jumps up and continues to rapidly go up but the vehicle doesnt accelerate significantly at all until after about 1.5 seconds or so when the rev counter is near the red line at which point the car accelerates rapidly.

The lag between going through the kickdown point and it actually putting the power down to the road doesnt seem normal to me but wondered if I am doing something wrong or not?
 

Peter De La Mare

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Mine doesn't exhibit those symptoms, though I feel all cars kick down one too many gears when you floor it, so I 3/4 floor it which I think produces better results.

Having said all this, I'll try it tomorrow and make notes, I'll report back.
 

st4

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Does the rev counter jump down, first, then you here the engine note change and feel the acceleration.

To be honest you can manually over ride the gears using the paddles. Drop into 3rd manually around 50mph, here the V6 sing then hit the go pedal.

It'll shift ;)
 
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I

InsideInsurance

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Does the rev counter jump down, first, then you here the engine note change and feel the acceleration.

I'll double check this afternoon.

From memory it doesn't during the phase when the revs go through the roof without any acceleration but when the acceleration does kick in I am concentrating on the road too much to see what the rev counter is doing.

Logically it wouldnt make sense that it drops a gear when its red lining but that's what physically it feels like.


Haven't used the paddles at all yet, its next on the list
 

Corned

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All autoboxes I have ever had have displayed this characteristic to some degree or other.

They all seem to need some 'thinking time' before reacting to sudden inputs. And the more sudden and/or demanding, the worse it gets.

My 5G has, on two conspicuous occasions, frightened the life out of me when I have suddenly needed a quick squirt of power. Once, attempting to exit a petrol forecourt into busy traffic, I spotted a gap (after much waiting), so I mashed the throttle to step smartly out across the road into the slot in the traffic. Except nothing much happened. I had time to bellow "Move, you b@5t@rd" in full before the car leapt forward, by which time the owner of a black X5 was almost in the side of my car, honking and flashing as he came - and rightly so! I would have been annoyed if I had been him.

My situation was made worse by the CDI engine, so there was turbo lag to add onto the gearbox indecisiveness.

I too wonder if a more progressive application of the throttle would yield much better results. In my case, I wonder if I experienced what aeronautical engineers call 'compressor stall', which happened to aero engines in days gone by if they were throttled up too quickly.
 


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