Auto (9-speed) 4th gear downshift revs

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

Simon Hi, I'm trying not to be patronising here - simply saying!
If this was a manual box you would not be changing down into 4th and dropping the clutch until you 'knew' the resulting revs uplift was going to be happily within the engine's comfort zone. I don't know whether there is an anomolous disparity in the auto ratios when you're clicking down from 5th (I assume) into 4th but it seems to me that you're obviously pushing it and the resulting rev rise is uncomfortable to the engine.
Diesels (I'm assuming it's a diesel but it wouldn't surprise me if you said it was petrol) thrive on torque not revs; perhaps you should consider letting the speed scrub off a tad more in 5th before you punish it again into 4th?
Just FMI have you perhaps thought of using the brakes a little to slow down rather than trying to use the engine as a vacuum pump?
After having said all this I realise now that my post is a little patronising and perhaps even a tad offensive but I can't help but conjure up an image of you driving this like a racing car. These cars may be nippy but you can abuse the privilege.
I personally intend to drive mine like Miss Daisy - that's why I have ordered an automatic.
Sorry for the tone but I couldn't help it.
All the best with your new car.
Walt.

(06-05-2015 09:33am)walterwindbag Wrote:  Simon Hi, I'm trying not to be patronising here - simply saying!
If this was a manual box you would not be changing down into 4th and dropping the clutch until you 'knew' the resulting revs uplift was going to be happily within the engine's comfort zone. I don't know whether there is an anomolous disparity in the auto ratios when you're clicking down from 5th (I assume) into 4th but it seems to me that you're obviously pushing it and the resulting rev rise is uncomfortable to the engine.
Diesels (I'm assuming it's a diesel but it wouldn't surprise me if you said it was petrol) thrive on torque not revs; perhaps you should consider letting the speed scrub off a tad more in 5th before you punish it again into 4th?
Just FMI have you perhaps thought of using the brakes a little to slow down rather than trying to use the engine as a vacuum pump?
After having said all this I realise now that my post is a little patronising and perhaps even a tad offensive but I can't help but conjure up an image of you driving this like a racing car. These cars may be nippy but you can abuse the privilege.
I personally intend to drive mine like Miss Daisy - that's why I have ordered an automatic.
Sorry for the tone but I couldn't help it.
All the best with your new car.
Walt.

Oo, er, missus!

(06-05-2015 09:48am)AndyFrance Wrote:  Oo, er, missus!

Have to say, if you are command shifting down from 5th at a point the engine revs are having to be raised that much, then the ECU will have to inject more fuel to raise the engine revs to match the lower gear, and that is likely why you are getting a pushing effect on the downshift. Does rather sound like you are downshifting before it's slowed enough to accept 4th.

I'm guessing the command shift would be rejected if it were damaging to the engine, what Revs are you reaching?

As Walter says.. If I did this in my manual, I'd expect to see high revs and would have to raise the engine revs myself using the throttle or generate a lot of heat in my clutch!

Hi guys, thanks for the responses.

I'm old enough to have had cars that I needed to double-de clutch to change gears, and I'm used to heel & toeing to change gears to match revs. I'm not offended by the note and happy that someone took the time to respond.

I too drive slowly and I use the command shift to check the cars speed when going down hill so don't end up going above the speed limit without using the brakes too much. I have a Disco 4 with the 8 speed box and a Defender TD5, so happy with the different operating modes of auto and manual.

So, my point is, if you're slowing down, at say 30mph and pull the down shift to give a little engine braking, the command shift may drop from 5th to 4th. Now the revs ( this is a diesel by the way) aren't high at that speed, say 1500..? The auto box (only on downshift to 4th) adds a lot of extra revs, above what is needed to match the road speed, so the net result is the car seems to accelerate for a second or two before it gets back to the speed I was driving at.

I'm probably not explain this at all well..!

In the Disco, the same process gives a nice, gentle controlled deceleration, with a little engine blip for each down shift, but no more. What is more, on the Evoque, this only happens on the downshift to 4th, the other gears behave as I expected.

I guess by the responses, no one else experiences this, or doesn't use the command shift so much...?

Cheers

Simon

Simon Hi, glad I didn't offend you but what you say now clarifies that you aren't a boy racer. I'm glad about that, I'm an old fart as well.
Seeing as you're playing around at quite low speeds and revs I suspect this is a mapping issue. As I said before I don't know whether there is a hole in the ratios between 5 and 4 but at these low speeds and revs I'm guessing the gearbox and the fuelling is not spot on for that down change. I'm guessing that the system is not entirely happy in 4th at 1500rpm and is juicing it to tell you. Perhaps it's thinking you're changing your mind and getting ready to gird your loins and go for it.
These boxes are a bit of a pain sometimes (as you've no doubt read) and I haven't even got mine yet!
I have a golf TDI with a 7 speed DSG just now, 54000 miles and I've only frigged it manually about 3 times - just to make sure it still works! I use S more often for racing at the lights!!
If I find myself overrunning on downslopes I use the brakes and then let the gearbox catch up on its own but it is a bit slow in slowing down.
Sorry for jumping to conclusions but it's about the only exercise I get nowadays.
All the best.
Walt

POLL: Who thinks Walt should go stand in the corner?

Just kidding Walt......

Regards to you and Simon

Hehe...

I was standing in the corner but I overshot slowing down!
Walt