Auto (9-speed) 4th gear downshift revs

(05-05-2015 06:22pm)couplands Wrote:  Hi,

Our 3 week old Dynamic Auto is great, but one thing seems to bother me (but it might just be me..!).

When downshifting using the "command shift" paddles into 4th, it seems to give the engine way too many revs. I understand that it gives a few more revs when down shifting in most of the gears, but 4th is so much that the car will accelerate slightly before slowing downing. This is very disconcerting as I use the downshift to help when travelling downhill (giving a bit of engine braking) and the acceleration occurs just when I need it to be slowing down.

Just wondered if anyone else has this issue..?

cheers

simon

Hi Simon

I have a 9 speed auto as well and have noticed this effect, the car actually seems to accelerate towards the hazard (or whatever reason you are changing down for, in your case a hill). I have found a solution that works for me. If you have your foot on the throttle as you change down the effect does not seem to be so great. The best way to describe it is to pretend you are driving a manual car, on approaching a corner (or downhill section or whatever) you would rev up the engine yourself with the throttle as you changed down to get a smooth change. When you do this on the 9 speed auto the car does not seem to 'run away' in the same way. I thought at first it was just because I was more mentally prepared for the downshift but I think it is more than that, I don't think the system revs up as much if you do it yourself.

(With respect to travelling downhill it may also help to follow the 'police system of car control' and slow down early (before the hill really gets steep) with the brakes then change down gears to hold your speed which is subtly different from using the brakes to slow you down. But this is very much a matter of personal preference and whether you've ever experienced any form of advanced driving tuition).

Anyway I've rambled on for far too long

Hope some of this helps at least

Gary

Gary,

I'm glad someone has also noticed the phenomenon and in fact you described it better than me...

I used the downhill situation as an example but as you say, any need to downshift to attain better control prior to a hazard will show the effect.

Ill give your "bit of throttle" approach a try.

Do you notice this in any other gear, on mine its only 6th that suffers from excessive throttle being applied by the autobox software..?

cheers

simon

ps Re: slowing before the hazard (in the example case the hill) is the approach I'm taking, and hence the spurt of acceleration is a surprise the first few times it happened. I'm used to it now so can compensate, but its still feels wrong. I passed my IAM test in 1983 and am still a member. I enjoyed many hours "observation" training with police class one drivers during my practice for the IAM exam.

Hi Simon

Nice to come across someone else who has received advanced driving instruction. I was active in the local IAM group here for many years both as an observer and, eventually, as chairman (didn't step back quickly enough when they asked for volunteers!). I'm a bit lapsed now and my RoSPA advanced driver's retest is, also, ahem, 6 years overdue!

Anyway back to Evqoues, yes I see how this over-revving issue also affects one when driving to the Police System of Car Control. I have to say that you have been more observant than I have in determining in which downshifts the effect is more pronounced. I will experiment with some 'relaxed throttle' downshifts into various gears when next out driving and report back.

Regards

Gary

(09-05-2015 10:58am)couplands Wrote:  Gary,

I'm glad someone has also noticed the phenomenon and in fact you described it better than me...

I used the downhill situation as an example but as you say, any need to downshift to attain better control prior to a hazard will show the effect.

Ill give your "bit of throttle" approach a try.

Do you notice this in any other gear, on mine its only 6th that suffers from excessive throttle being applied by the autobox software..?

cheers

simon

ps Re: slowing before the hazard (in the example case the hill) is the approach I'm taking, and hence the spurt of acceleration is a surprise the first few times it happened. I'm used to it now so can compensate, but its still feels wrong. I passed my IAM test in 1983 and am still a member. I enjoyed many hours "observation" training with police class one drivers during my practice for the IAM exam.

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