7 sp DSG niggle.

[Stoney!]

I think you will find its the supercharger, it does it to me even in the manual sometimes.... The supercharger will sometimes cut in after a gear change if the revs are low but then instantly think its not needed if your being easy on the gas and therefore cut out. The the quick pause your feeling for a literally a second is the time between the supercharger cutting out and the turbo coming on boost.

Take it out into a REALLY quiet area, probably at night time and see if you can hear the supercharger or the supercharger clutch (the clicking sound as it cuts in and out) following the trend mentioned above, I think you will find this is exactly what it is. Also listen for the slight whistle (or whoosh) of the turbo directly after.

Stoney!

[Stoney!]

Anyone else with a manual or DSG 118tsi agree with the above sentiments?

I even had it do it to me on the demo I drove 4 or 5 months ago, so its completely normal, and I think what I've written above is exactly what it is.... I've even had it when driving hard before.....

Stoney!

[logger]

..The supercharger will sometimes cut in after a gear change if the revs are low but then instantly think its not needed if your being easy on the gas and therefore cut out. The the quick pause your feeling for a literally a second is the time between the supercharger cutting out and the turbo coming on boost...
Anyone else with a manual or DSG 118tsi agree with the above sentiments?

I am not so sure. I tend to disagree for several reasons.
Firstly the simplistic reason - you are describing turbo lag which is the very thing the engines configuration was designed to prevent.
Secondly along more technical lines, the supercharger does not just cut out at low revs when there there is no demand for boost. If the revs are below 2400 it can in principal run continuously (except for very low load) providing for the regulating flap to modulate closed in ~ 0.2 sec to rapidly boost the engine. Hence the design to avoid turbo lag. With part throttle and revs at 1200 pressing the acellerator will readily increase the boost from 1000 to over 2000mbar in 2 secs. No lag.

Also I think most people will be surprised how briefly the supercharger is used as compared to how often it runs. For example it may boost the engine for as little as 2 seconds as the engine accelerates, before the modulating flap opens allowing the turbo to assume the boost load. There is no bump in the boost pressure as this happens. It is all done smoothly. From what I have observed the supercharger boost generally cuts out before 2400 rpm although it can run up to 3500rpm apparently. It will not run above ~3500 so that it does not $hit itself. It will be doing 17,500rpm at this point!!

BTW I have never heard the clutch clicking noise (must be one of the lucky ones) but I can certainly hear the modulating flap noise when I turn the IGN on and perhaps this is what you can hear in a quite environment with the engine running at low revs.

My guess is CME2C's DSG niggle/lag/pause is more related to how the DSG processes the gear changes and controls the engine torque while doing so. I know from looking at the clutches that it is not uncommon for it to slip the K1 clutch all the way through 1st until it engages K2 for second - So the 1st to 2nd change will happen really quick and early and imperceptibly. It never fully got into 1st you see. At this point is will be in 2nd with K2 engaged without slip, it will have selected 3rd and swap the clutches to take K1 again and 3rd without slip. So possibly it deals with the 1-2 change differently to the 2-3 change. As the DSG7 effects and control the engine torque it could quite will be doing slightly different things for each of the changes. For instance a greater torque drop for the 2-3 change would show up as a pause to the driver. For the 1-2 change as both clutches are slipping the whole way little or no torque drop as the change occurs. Anyway just an idea.

[MaccaTSI]

I think my car does this as well. But I'm not sure if it's the same issue.

Sometimes if I accelerate hard after I've been cruising along, to overtake or something, I'll hit the accelerator and it will rev from about 2k - 4k before accelerating. I thought it was just downshifting before accelerating and that's what was causing the pause, but the other day after reading this I noticed it was staying in the same gear.

It's probably only a one second pause.

Is that the same thing??

[logger]

I am not sure. Doesn't make a lot of sense - Eng rpm doubling without accelerating when in a constant gear, unless a clutch is being slipped.

Here is a small xls spreadsheet showing Supercharger regulation during a 2 minute drive. It shows to some degree how quickly the supercharger can build the boost. Also shows how briefly it is actually used. May be of interests to some of you.

[MaccaTSI]

Re: 7 sp DSG niggle.

It's not like it just doubles, it accelerates a bit but doesn't fully kick in I guess, like it goes a bit, then at 4000 it really accelerates.

I'll have a play around and see if it's just me, have only just noticed it so haven't had a chance to really test it.

Thanks for the info logger, I'll have a read through it

[CatonaPC©]

Have you tried resetting the DSG? With the vehicle stopped and engine turned off press the accelerator completely to the floor . . ..

This is not true. You need a VAGCOM setup to do this and it's a lengthy procedure, I have been told. The above procedure is supposedly something one could do to reset the throttle range. It's most likely a myth.

[cme2c]

I am not sure. Doesn't make a lot of sense - Eng rpm doubling without accelerating when in a constant gear, unless a clutch is being slipped.

Here is a small xls spreadsheet showing Supercharger regulation during a 2 minute drive. It shows to some degree how quickly the supercharger can build the boost. Also shows how briefly it is actually used. May be of interests to some of you.

Thanks for that, logger, it's really interesting. Seems like an expensive solution to turbo lag from the larger turbo (than the 90TSI) . It certainly works, though. Having driven the GTI which is almost lag free, the 118 is better IMHO.

[logger]

Yes I agree - it certainly seems to work very nicely. I have no complaints and I am very much enjoying the car. Really is surprising how little the S-Charger is used though

[mr gee]

Logger
can you determine when the supercharger clutch activates?

I think the hesitation could be due to the drag when the clutch activates at around 1000rpm before boost compensates. it certainly not so evident when a purposeful prod of the accelerator is used.

[logger]

Logger
can you determine when the supercharger clutch activates?

No unfortunately. Thats the one piece of the jigsaw that still has me beat.

I reckon there may be a gap between supercharger clutch engaging and the regulating flap closing to load it up. So I am not sure how much "drag" there would be on engagement. But I cannot know this for sure until I work out how to watch either the PWM or the clutch voltage.

[Stoney!]

Has anyone else noticed (manual) that sometimes when you enter a corner in gear above say 1500 rpm and with foot flat to the floor it feels a bit numb whilst waiting for the turbo to boost, i thought the supercharger was supposed to kick in at call to cover the turbo lag?

Stoney!

[mr gee]

If I enter a tight corner, I drop to "S" mode so that I get a lower gear to deal with that

[Stoney!]

Sorry but what a silly reply, it contributed nothing to the topic of conversation, I already stated I have a manual and was asking why the supercharger wasn't compensating for the turbo lag as its supposed to, good on you for knocking it back a gear, i could do that too but choose not too.

Stoney!

[cktsi]

Has anyone else noticed (manual) that sometimes when you enter a corner in gear above say 1500 rpm and with foot flat to the floor it feels a bit numb whilst waiting for the turbo to boost, i thought the supercharger was supposed to kick in at call to cover the turbo lag?

Stoney!

I know you're looking for a response from a manual driver, but oftentimes I'm driving only with the tiptronic on the DSG, so characteristics should be similar since it's also a clutch setup in the transmission (though the ratios are different). So thought to ask a question & write something about my observations.

Which gear are you in when this happens and are you specifically asking about corners because it only happens in corners? I've played around a bit in straight lines and noticed that the car is more responsive in the 1500rpm rev range between different gears (that goes without saying - duh)... but the point is.... it is quite striking how much the difference is.

The engine spins like a feral in 1st & 2nd, but in 3rd gear it's nowhere near the push in the back sensation I get from 1st & 2nd.