1.0 TSI manual: difficult to pull away smoothly

[gogo110]

Hi,

 

I've got a 2023 Fabia Mk4 1.0 TSI 6 speed manual, and even after 6000 km on the clock I cannot consistently get a smooth start from a standstill. What happens is that I give it some gas (about 1.5k RPM), bring the clutch up to the bite point, the car starts to move, I continue to hold the clutch at the bite point, but once the clutch plate engages completely it is as if the car briefly cuts acceleration (resulting in a stutter) before resuming to accelerate normally as I apply more gas. Now, I've tried multiple things to mitigate this, including giving it more gas from the start (about 2k RPM), giving it more gas as the clutch begins to bite, etc. And it sometimes works and I can pull away smoothly, but it is inconsistent and there doesn't seem to be a rule when it will judder and when it will not. The only circumstance under which no stutter occurs is if I pull away without giving any gas (but that is too slow for normal traffic). Now I've owned other manual cars and haven't had this problem before.

 

Has anyone else experienced something like this?

 

[Warrior193]

Hello gogo, welcome to the forum. I'd suggest having the throttle module scanned. One thing you could try - switch the drive mode to sport and see it that improves things.

Edited 26 October, 2023 by Warrior193
typo

[gogo110]

Well, before taking the car to a garage I'll get someone else to drive it (some friends have TSI cars as well), to rule out operator error Regarding the drive modes, unfortunately I don't have that specced on my model.

[Warrior193]

2 hours ago, gogo110 said:

Well, before taking the car to a garage I'll get someone else to drive it (some friends have TSI cars as well), to rule out operator error Regarding the drive modes, unfortunately I don't have that specced on my model.

Are you sure? - the spec sheets I've seen for the Mk 4 Fabia appears to suggest drive modes are standard.

[gogo110]

Yep, pretty sure. It's not a UK market model

[SurreyJohn]

On 27/10/2023 at 20:09, Warrior193 said:

Are you sure? - the spec sheets I've seen for the Mk 4 Fabia appears to suggest drive modes are standard.

The UK brochure has no model with drive mode as standard, shows as cost option on Monte Carlo spec only

 

Only 4 of 15 specs in UK come with 6speed manual gearbox, so not going to be that common here either. 7 of 15 UK specs are 7speed DSG

 

https://www.skoda.co.uk/_doc/775d73bc-eb9d-4a50-911e-863d73b99333
 

[ettlz]

Welcome to wonderful world of electronic throttle pedals trying to second-guess your driving intent. Additionally, the Fabia's clutch and gas pedals are incredibly light which makes it harder for the brain to judge exactly where the pedals are and what commands they're sending to the vehicle. What I've found:

• There's an inactive spot at the top of the gas pedal travel. (The ECU sees all this movement, it just ignores it.) Beyond that zone the pedal response is very sensitive so fine foot control is required. Techniques for fine control include using the arch of the foot (which is more sensitive and moves less) or using the right of the ball of the foot with a twisting motion.
• The clutch goes from biting to slipping to fully enagaged roughly in the middle of the pedal's travel over a region that's smaller than you'd expect. This can be hard to judge from the lack of feedback underfoot.

I suspect what's happening is as follows:

1. You set the gas, and pull the clutch up to biting point.
2. The car begins to accelerate and the front end lifts. You continue to lift the clutch pedal, and apply sufficient throttle to keep the engine revs level.
3. The clutch pedal reaches a point where it's engaging more than you think, which slows down the engine a bit.
4. Finally the clutch then engages fully, so the car's speed is suddenly locked to the engine's. The car stops accelerating and the front end dips down. The loss of acceleration is what you feel.

So you can try, in combination depending upon requirements:

• Slow down what happens in steps 3-4 by identifying the bit of pedal travel just before full clutch engagement and slowing your left foot's movement. This gives two sides a bit more time to equalise their speeds.
• Apply a little more gas progressively throughout engagment, so that the car continues to accelerate throughout engagement, but with a softer edge as the car transitions to constant speed. See the note on fine pedal control above.
• If the car's going fast enough for it, just change to 2nd gear before fully engaging the clutch anyway.

Obviously don't torture the clutch with excessive slipping or rev differences.

 

Other considerations:

• As soon as the clutch starts to bite, if possible get both hands on the steering wheel and keep a good driving posture to help pedal control. Feel the car's acceleration response as it the clutch acts.
• Use different footwear. I'm not joking here -- anything that alters my foot sensitivity or the thickness underfoot throws out my smoothness until my brain recalibrates.

Edited 19 November, 2023 by ettlz

[offthewall]

WOW !!!

If this is modern driving I'm even more glad I got the supremely wonderful DSG auto box.

[Brio]

I get exactly the same on my Scala  1.0 110 6 speed, its like when you get to the top of the clutch, the computerised throttle assist suddenly hands back to the driver and if you don't increase throttle at precisely that moment, you get a sudden lurch. Guess most people are getting the DSG

[gogo110]

Thanks for the advice. My friend has driven the car and had no issues. Turns out it's a skill issue after all. I've been practicing adding more gas at the right moment and can now get a smooth start most of the times. It helps when you can hear the engine, the sound changes slightly throughout the process and gives you a cue when to act. I guess it'll take some more practice until it becomes muscle memory.

[andreiro221]

Same issue with Kamiq TSI and the dealer replaced the clutch master cylinder.

 

All good after that, the car behaves like it should. It starts very smooth now.

[gumdrop]

I noticed the Autocar review was uncomplimentary about the pulling away performance.

https://www.autocar.co.uk/car-review/skoda/fabia  Engines and performance.

[Tintowellfan]

That review was of the car fitted with a five speed gearbox, pretty sure the OP was commenting on his six speed box.

 

[xman]

I drove a 1.0tsi Kamiq 6 speed manual hire car in Poland last year. It was surprisingly smooth and tractable. You could pull away with virtually nil gas pedal input. It had great acceleration, only flooring it at low revs (<1800 rpm) gave away it was the 3 cylinder, but not in an unpleasant way.

 

I did notice the idle speed changing and adapting when pulling away from a standstill. But didn't interfere with the experience.

 

I'm guessing there may be clutch related issues at play here as others have posted.

[johnrogers]

I've got the same problem after buying an 8 month Fabia Monte Carlo from a main dealer, I just can't get away without getting that lull or a jerky start, won't be joining fast moving traffic any time soon... I'll give it another couple of weeks then back to the dealer.

[johnrogers]

On 26/10/2023 at 20:03, gogo110 said:

Hi,

 

I've got a 2023 Fabia Mk4 1.0 TSI 6 speed manual, and even after 6000 km on the clock I cannot consistently get a smooth start from a standstill. What happens is that I give it some gas (about 1.5k RPM), bring the clutch up to the bite point, the car starts to move, I continue to hold the clutch at the bite point, but once the clutch plate engages completely it is as if the car briefly cuts acceleration (resulting in a stutter) before resuming to accelerate normally as I apply more gas. Now, I've tried multiple things to mitigate this, including giving it more gas from the start (about 2k RPM), giving it more gas as the clutch begins to bite, etc. And it sometimes works and I can pull away smoothly, but it is inconsistent and there doesn't seem to be a rule when it will judder and when it will not. The only circumstance under which no stutter occurs is if I pull away without giving any gas (but that is too slow for normal traffic). Now I've owned other manual cars and haven't had this problem before.

 

Has anyone else experienced something like this?

 

 

Just now, johnrogers said:

Did you get this sorted??

 

[gogo110]

Hi @johnrogers,

 

I'd like to clarify that the problem I've described is not one of making a fast start, but of making a smooth start (especially one that is not very fast!). From your description in the other topic it seems you are struggling to accelerate quickly. You're probably not giving it enough gas, try to press the pedal more than you think is necessary. The throttle pedal map is non-linear and rather weird.

 

As for my problem, there has been some development on it, I'll write in more detail when I get the time.

[gumdrop]

I think my Fabia Kombi Monte Carlo was six speed It drove beautifully full of camping gear or a dash across the bridge to Wales.

Engine/gearbox was very smooth

[jduarte8]

On 06/02/2024 at 23:23, gogo110 said:

Hi @johnrogers,

 

I'd like to clarify that the problem I've described is not one of making a fast start, but of making a smooth start (especially one that is not very fast!). From your description in the other topic it seems you are struggling to accelerate quickly. You're probably not giving it enough gas, try to press the pedal more than you think is necessary. The throttle pedal map is non-linear and rather weird.

 

As for my problem, there has been some development on it, I'll write in more detail when I get the time.

Hi @gogo110,

 

My 2022 VW Polo has the exact same problem and I think this is not normal. I don't have problems pulling away fast and smoothly. The problem is when taking away slowly. When the clutch fully engages the car jerks. If you could share the development I would really appreciate. 

[gogo110]

Hi.

 

So, the car was at the dealer for an unrelated issue, and I've mentioned this as well. Two technicians drove it, and they said the car pulls away smoothly.

I've also driven a 2020 VW Polo (95 BHP), using the "standard" methods of clutch/gas operation (the way I was used to on other cars) and also noticed the jolt when starting. However, the owner of that car can move off nice and smooth each time.

 

So, from this I can conclude two things: the issue can be evaded by using an appropriate driving technique, and, the issue is not tied to my vehicle in particular. Especially since other people have complained of it, not just on this forum, but elsewhere as well.

 

Fabia MkIV, German Skoda forum

VW Taigo

 

In matter of fact, this whole thing sounds eerily similar the infamous 1.5 TSI kangaroo issue. I've taken the liberty to scroll through hundreds of forum pages related to that problem, and while some people complained of the "true" kangaroo, where the car would jump at low speeds while in gear (when engine was cold); some complained of not being able to start from a standstill smoothly.

 

E.g. from 1.5 SEL first gear issue

Quote

Had my Karoq 1.5 manual 3 months now and still the same problem of moving off smoothly which is impossible unless the revs are kept above 2000. (...)

 

While the first problem was solved by a software update to the engine ECU, the second, it would seem, was not.

 

---

 

Now, I was still keen to find out why the car actually jolts, and how one should optimize his/her driving technique to avoid issue.

 

Well, it turns out that this problem is actually well known in the field of automotive engineering. I've found online a terrific paper that describes it in detail:

 

Dry Clutch Control for Automotive Applications by Dolcini et. al., courtesy of Renault S.A. and GIPSA-lab, available here: https://hal.science/hal-00536612/document

 

The chapter of interest is chapter 3: Clutch comfort

 

The key takeaway is this:

"When the crankshaft and the gearbox primary shaft are synchronized (...) the clutch behaves like a simple linking element inducing a sudden change in transmitted torque which causes a highly uncomfortable oscillation of the driveline (...)"

 

This matches with my experience that a jolt is felt at the moment the clutch synchronizes (stops slipping).

 

There is a detailed mathematical analysis of phenomenon within the paper for those that are interested. But lest I burden everyone with equations, I'll just summarize the most important points:
-while the clutch is slipping, the rate of acceleration of the car is determined by the torque transmitted by the clutch. This torque is, in turn, defined by how high the driver has lifted the clutch pedal.
(also observe how adding more gas while the clutch is slipping and with the clutch pedal at a set position will not make the car accelerate faster)
-in order to reduce the amplitude of the oscillation at the clutch synchronization instant, one has to either reduce clutch torque (=not lift the pedal as high, but this also means less acceleration) or increase engine torque

 

Now, one more thing to note is that the fact that the engine is revving at e.g. 2000 RPM that does not necessarily mean that the engine is producing the maximum 200 Nm of torque (1.0 TSI). One has also take into account how wide the throttle body is open. If the engine is not loaded (clutch disengaged), the throttle does not have to open very wide in order for the engine to rev to 2000 RPM.

 

So if your start procedure looks like this:
1. Clutch pedal pressed all the way, add gas up to 2000 revs
2. Lift clutch pedal (not pressing gas pedal more simultaneously) until you attain rate of acceleration typical for starting off from a traffic light
3. Wait until clutch synchronizes
4. Lift clutch pedal completely, apply more gas

 

You will get a jolt at the end of step 3, reproducible 100% of times on the 1.0 TSI.

 

Now, most people will actually add gas simultaneously with lifting the clutch in step 2, including myself. However, if you do not press the pedal sufficiently (=request sufficient torque from the engine), you will still get a jolt. The problem on the 1.0 TSI is that the engine will sound and feel completely fine (like it's not struggling) all the way until the car suddenly and unexpectedly stutters. Now, for different rates of acceleration, it can be rather difficult (at least for myself) to judge how much you have to press the gas pedal at step 2 in order to be smooth. But what I've found you can do is to press the gas pedal additionally during step 3 (about a second after stopping lifting the clutch pedal) you'll get a smooth start. If you do it too late, it will jolt.

 

A few more things I'd like to comment:
-if you set off without gas, the anti-stall function will keep revs at ~1200 and also ensure sufficient engine torque, meaning no lurch. However this only works for slower starts. Lift the clutch too high and you'll stall.
-just after starting the engine, the ECU will keep idle revs at 1500, making it easier to start smoothly with less gas pedal input.
-I've driven a 1.5 TSI manual Scala (the way I was used to operating the clutch/gas before the Fabia) and it was smooth.
-in theory, at the end of step 3, you could press clutch pedal slightly in, and it should smooth things out. However, timing-wise, it would probably be even more restrictive then additional throttle application. I haven't tried this.  

 

TLDR:
The jolt happens if the engine is not producing enough torque at the clutch synchronization instant. This is not a fault, but a physical property of the engine-drivetrain system. Drivers should adapt their driving style accordingly.