Twincharger 7DSG - Selects higher gear than it should. Thoughts?

[prise]

My experience is different to yours. I've plotted logged engine load against RPM for my vehicle and the DSG7 does not stay long in the high load/low RPM area before downshifting. I have also experimented with manually overriding to a lower gear going up hills on cruise control and found the instantaneous fuel consumption to increase slightly so no complaints in the DSG calibration with my vehicle. A colleague had the same comments as you with his manual TSI wrt the shift indicator - complaining that the engine was labouring and using more fuel when he followed its instructions. His engine subsequenty started idleing rough and VW replaced all four fuel injectors. He now finds the shift indicator suggestion to be fairly accurate and the engine no longer labours.

The greater 'perceived' vibration experienced at lower RPM is normal for tuned vibration isolation mounts as the % of vibration transmitted increases as RPM drops towards the natural frequency of the engine mounting system.

[MariusGT]

i have kept an eye on the instantaneous fuel consumption and noticed that a lower gear + slightly higher RPM (little or no boost from guage) will use less fuel than the tall gear using more boost.

also, when using cruise control the DSG seems to want to stay in the taller gear more than if you are controlling the pressure on accelerator. if that makes sense?

Not cruise control: drops back to 5th or even 4th going up a certain steepish hill at 60kmp/h
using cruise control: on same hill at same approx speed will stay in 6th much longer and eventually drop back to 5th.

[logger]

...The whole thread revolves around the noticably greater vibration of the engine when running with large throttle openings and when the DSG decides to shift up early.

Funny that. I started the thread, commenting on how the twincharger/DSG7 combo will "...readily run at lower revs and a higher gear than most of us are used to...". Nothing about throttle openings. It is a chracteristic of the way it has been designed and configured to operate.

...while it may not be WOT, the throttle must be fairly open for the engine to load up enough for the engine mounts to be stressed in this manner.

Yeah I suppose 58% is fairly open. It is also fairly closed

Remember that with Electronic Power Control, the pedal is a power request lever and not a throttle lever. Push flat to the floor to command 100% power and ECU will "specify" an achievable load within its envelope and the engine will respond with an "actual" load. So for example; while foot to floor will give a commanded load of "WOT", throttle angle will most often be a mere fraction of this. At 1500rpm the throttle is just over 1/2 open at 58%. At 2000rpm 66%. You have to get to 5000rpm before you will actually see the throttle wide open!!

.. I've found manually shifting later in these circumstances not only reduces the vibration but also the fuel consumption and increases acceleration so the DSG programming is not optimal in these situations. This makes the notion that "I do not believe the designers would allow them to so readily operate in a regime where it could damage itself" a bit of a leap of faith, in my book.

Fair enough. I'll stick to having faith in the designers and rely on my warranty if they get it wrong. Lets hope they get it right with the brakes

My experience is different to yours. I've plotted logged engine load against RPM for my vehicle and the DSG7 does not stay long in the high load/low RPM area before downshifting. I have also experimented with manually overriding to a lower gear going up hills on cruise control and found the instantaneous fuel consumption to increase slightly so no complaints in the DSG calibration with my vehicle.

I agree. You have to intervene and place the DSG7 in manual mode to get a sustained high load at low rpm. Even then you will not not see peak loads for more than a couple of seconds before it will override you and downshift.

The greater 'perceived' vibration experienced at lower RPM is normal for tuned vibration isolation mounts as the % of vibration transmitted increases as RPM drops towards the natural frequency of the engine mounting system.

Makes sense. I actually don't mind it all. I find it a pleasant reminder of the cars ability to pull from low revs.

[Stoney!]

I'd be inclined to say the noises being heard are the injectors rattling away at low RPM, Direct injection is known for it's noisy clatter on idle and under load. Whilst it's probably not the nicest sound, I highly doubt its doing any damage, that said is there anyone that can Flash a DSG, because 7th in local speed limits sounds a bit outrageous to me.

I to have also noticed keeping the revs up on the 118tsi uses less fuel then plonking down through the gears and climbing hills at 1700rpm with the supercharger howling, And I often wondered being a manual driver how the DSG copes in this area, whether the program is intuitive enough to keep the engine in its power and economy sweet spot on hills of around 2200rpm. I got my answer now and clearly it's no.

Stoney!

[Ryan_R]

If I'm in a hilly area with a low speed limit (i.e. 60) the DSG will often change down as if it wants me to boot it up the hill (I can nearly hear it saying "c'mon slow poke" - actually that's probably me saying it to the person in front). In such cases I switch to manual and change gears between 4-6 to keep things smoother.

[RW1]

This may be of interest....

As part of some misfire investigations I've been doing, I re-gapped the factory fitted spark plugs from 0.91mm (36 thou) to 0.79 (31 thou) [VW Maintenance Manual Spec is 0.8mm to 0.9mm]. VW plugs supplied as spares are also gapped at 0.91mm.

The effect has been a smoother engine at lower rpm. As a consequence the 7 speed DSG has been better at handling the gears in the region of 1,700rpm - 2,100rpm. Where in the past I would get gear change down on some hills, the car now pulls up the same hill inclines smoothly without dropping a gear in most instances. The engine is quieter too, both at start-up with that diesel noise period initially and also while driving - almost silent inside the cabin. Gear changes are generally smoother across the gears and engine rpm's and the first gear lurching has gone.

[Brian]

This may be of interest....

As part of some misfire investigations I've been doing, I re-gapped the factory fitted spark plugs from 0.91mm (36 thou) to 0.79 (31 thou) [VW Maintenance Manual Spec is 0.8mm to 0.9mm]. VW plugs supplied as spares are also gapped at 0.91mm.

The effect has been a smoother engine at lower rpm. As a consequence the 7 speed DSG has been better at handling the gears in the region of 1,700rpm - 2,100rpm. Where in the past I would get gear change down on some hills, the car now pulls up the same hill inclines smoothly without dropping a gear in most instances. The engine is quieter too, both at start-up with that diesel noise period initially and also while driving - almost silent inside the cabin. Gear changes are generally smoother across the gears and engine rpm's and the first gear lurching has gone.

Hows it go at higher revs? eg 5k +.
Years ago I played with spark plug gaps endlessly.
General result was:
Smaller gaps = easier starting and smoother running from idle to around 4k revs but with some misfires towards redline (~ 6k in those days)
Larger gaps = u guessed it - harder starting and poorer low end performance but clean and crisp at the top end.
Mind you Im talking non ECU controlled cars here - just plain old dizzy and carbie. You could end up with thousands of combos by playing with the timing as well..

[RW1]

Hows it go at higher revs? eg 5k +

Gear changes are generally smoother across the gears and engine rpm's

I have accidentally hit 6.800 rpm without realising it until I looked down at the rev counter to see the pointer well into the red band, it's that smooth. Strange thing, that was in DSG "D" mode.

[Brian]

I have accidentally hit 6.800 rpm without realising it until I looked down at the rev counter to see the pointer well into the red band, it's that smooth. Strange thing, that was in DSG "D" mode.

Interesting. I think Ill pull the plugs and see what they are set at. The rough idle on start up annoys the p*ss out of me. Will report back.
Surprising to see the car rev to 6800 in "D' mode. I cant get it past 6500 (in ANY mode) without it changing up. Maybe I need heavier boots! LOL
Thanks RW1