Originally Posted by mmcrh
Back from Wollongong to Sydney via Bulli. Went through some steep uphills. Engaged paddle shift mode on uphills, guess what happen. Press gas pedal gradually more than half way through, yet Nil response from engine, e.g, no rpm increase, no nothing. At time of engaging paddle shift mode, gear was 4th, speed was 30kph. I had to change to auto mode, otherwise car would rolling backward.
No problem when drove on same sections of Rds on downhill using paddle shift.
Bulli pass is a pretty steep hill going up.
You need plenty of torque going up there. The engine has the best Torque 570Nm between 1800-2500 revs and still has more than 500Nm
Heres the engine webpage: A 630 DOHC: V6 Motors Engine Euro5 emission 250 CV - VM Motori
When the revs are too low there is not much torque/power for pulling up the hills. (Looks at the blue & red lines on the left side of the graph)
Manual mode : 4th gear at 30kph is only about 1250rpm !! way too low revs
to to pull up a steeps hill.
In manual, you are the one to select the correct gear. You
should be changing down to 3rd or even 2nd to drive smoothly up the hill.
You should be keeping the revs up to around 2000rpm or more to go up a steep hill.
Trying to push up in 4th, it doesn't matter how much accelerator pedal you give there
When you switched back to auto mode the gearbox's "brain" would have done the correct thing and changed down to 2nd or 3rd.
Going downhill there is not any load on the engine, foot of the accelerator. Hey it does not even need to inject any fuel in.
Originally Posted by mmcrh
Are you saying engine would stall if inappropriate gear selected? To start, this car is smart enough (per users manual) to simply ignore drivers selection if its inappropriate, e.g., the car ignores my upshift to gear 6th at 40kph. In addition, engine shall not stall even inappropriate gear was selected. In my case, it just like pressing gas pedal as if engine's off.
The gearbox software has to make decision to override the drivers selection when it is not appropriate before stalling or if over revving. They have to make it idiot proof.
In your situation above, It would eventually go out of your manual selection before stalling the car.
Test it. Put the car in manual gear 4th or 3rd and then bring the car to a stop with the brakes. It will change to 1st gear just as you stop, without stalling.
The same thing if you revved it in 1st gear all the way to the the rev limiter, in manual it would automatically change gear.
Have you driven a manual car before?
When driving in the manual you want to keep the engine revving in the range where the power/torque is. With our diesel there is a nice wide rev range from 1800 up to 3500rpm
with lots of torque so it should be easy.
For example - normal driving up from stopped up to 55kph in manual
Rev in 1st up to about 2900rpm. (about 25kph)
Change to 2nd and the revs will drop to about 1900rpm - still in the good part of the power range.
Keep in 2nd going through up to 2900rpm again (about 39kph),
Change to 3rd and the engine revs go to 1950rpm agin.
rev in 3rd up to 2900rpm again and this will be about 55kph.
Change to 4th and the revs will drop to about 2100rpm etc etc
In each gear you are using the same part of the of the rev range where the most amount of torque is. It's giving up over 500Nm if you need it in that range.
If the revs drop right down (like you were, 4th at 30kph , 1200rpm) there is only about 50kW of power and less than 1/3 of the engine's torque (max 150Nm) so you're going nowhere trying to climb a steep hill.