Lag switching between drive and reverse

[fast-ferret]

Not sure if this is anything of concern but when I’m switching between drive and reverse it can sometimes take some time, sometimes more than a second, maybe a second or two - especially if I’m in reverse and am going something such as 5mph and I put it in drive I can travel some distance before first engages. Is this fairly normal or unusual?


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[Russboy]

Not sure if this is anything of concern but when I’m switching between drive and reverse it can sometimes take some time, sometimes more than a second, maybe a second or two - especially if I’m in reverse and am going something such as 5mph and I put it in drive I can travel some distance before first engages. Is this fairly normal or unusual?


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Presume DSG? If so, quite common I believe.

I've learnt in Asda car park to be a little patient for it to engage.

 

[youngy93]

i would always make sure the car is static when changing between forward and reverse, might be waiting for the speed to drop before changing?

 

[fast-ferret]

Sorry yes I have it in my head that all S4’s are DSG, not the I know! But yes, it’s a DSG. I imagine it’s best to be static but I suppose I’m used to “normal” autos (CVT I guess) which let you go in reverse just fine, I assume DSG boxes aren’t too Ken en engaging drive whilst you are going backwards?

Re the Asda car park - yes I can imagine! If I were in a car park yesterday I’d have hit something as it took quite some time to engage. I must have travelled a meter or two.


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[jdp1962]

And I thought Audi drivers only shopped in Waitrose......

 

[Russboy]

And I thought Audi drivers only shopped in Waitrose......

Gotta save some money somewhere to be able to afford the petrol for the S4!

 

[Russboy]

Sorry yes I have it in my head that all S4’s are DSG, not the I know! But yes, it’s a DSG. I imagine it’s best to be static but I suppose I’m used to “normal” autos (CVT I guess) which let you go in reverse just fine, I assume DSG boxes aren’t too Ken en engaging drive whilst you are going backwards?

Re the Asda car park - yes I can imagine! If I were in a car park yesterday I’d have hit something as it took quite some time to engage. I must have travelled a meter or two.


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It's just something you get used to. Used to bother me, but now I know I was just asking it to change too quickly.

 

[rum4mo]

I never ever take my S4 into our local Waitrose car park as it is a very compact roof park affair, that is a job for wife's Polo, and if busy I stay in the car and move it around when cars get too close, its all to do with trying to keep away from the walk way as idiots use it to widen their car parking slot - and that forces the trolley drivers to try to squeeze between cars well away from the now semi blocked walk way, selfish donkeys!

 

[Dippy]

Is this fairly normal or unusual?

Normal. 1st is on shaft/clutch1 and R is on shaft/clutch2. The TCU needs to protect the clutches from overheating/wear and in fact instructs the ECU to reduce torque during the overlap as the gears change. This is doubly important when switching between 1st and R. My expectation is that the TCU should actually refuse to select 1st until the car has stopped moving from R (and vice-versa). The delay should be for it to prove to itself that the car is static. Have you actually found that you can force your car to apply 1st gear to stop reverse travel? If you have I'm going to be surprised (and suggest that you stop doing it).

 

[fast-ferret]

Normal. 1st is on shaft/clutch1 and R is on shaft/clutch2. The TCU needs to protect the clutches from overheating/wear and in fact instructs the ECU to reduce torque during the overlap as the gears change. This is doubly important when switching between 1st and R. My expectation is that the TCU should actually refuse to select 1st until the car has stopped moving from R (and vice-versa). The delay should be for it to prove to itself that the car is static. Have you actually found that you can force your car to apply 1st gear to stop reverse travel? If you have I'm going to be surprised (and suggest that you stop doing it).

Now you ask the question I question myself but yes I would say so but only from quite slow speeds.

Something else I noticed today very randomly (i have never tried this before) is that I put the car in N and let off the brake for about 10 seconds, when I reapplies the brake and put it on D it took a good couple of seconds to engage, I may have applied the accelerator too soon perhaps though which may explain why? Tried it again and no such delay.

Thanks for the info.


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[Dippy]

As you know, there are various messages that come up on the DIS telling you what to do or not to do with brakes and transmission select lever. This is just good German safety engineering. Whilst a second or two delay can be irritating, it makes sense if the control unit is simply doing what it needs to do to protect the transmission from damage.

I have a Miele (German) coffee machine and it is far more unforgiving than my S5. Sometimes I need to open the door and close it again just in order for the control unit to recognise that I have completed an action and so it can go to the next step.

 

[fast-ferret]

As you know, there are various messages that come up on the DIS telling you what to do or not to do with brakes and transmission select lever. This is just good German safety engineering. Whilst a second or two delay can be irritating, it makes sense if the control unit is simply doing what it needs to do to protect the transmission from damage.

I have a Miele (German) coffee machine and it is far more unforgiving than my S5. Sometimes I need to open the door and close it again just in order for the control unit to recognise that I have completed an action and so it can go to the next step.

Yes definitely sensible, and as long as it’s fairly normal I’m happy enough, I just hadn’t really noticed it before.

This leads me on to something else, this may possibly be me noticing things that aren’t there, but I could swear that when the car is cold it is more sluggish in reverse than when warmed up. When I say at the moment I suppose I mean winter (I haven’t noticed it before then, it occurring now may just be a coincidence in any case).

It feels like the clutches don’t engage quite as quick or with quite as much pressure. When I say sluggish I’m not talking about the time to engage reverse, I’m talking the time to start moving when pressing the accelerator, with reverse having been engaged for enough time for it to select. Feels like riding the clutch in a manual a little.

Might be in my mind..


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