So I have a 2021 Skoda Octavia 4 (ambition). I already have numerous problems with it explained here: https://www.briskoda.net/forums/topic/507885-issues-with-skoda-octavia-2021-combi-15-tsi/?_fromLogin=1

 

 

But something else I didn't explain in the other thread is more concerning to me.

So when I drive in 2nd, 3rd or 4th at sub 2k rpm (or around it) there are vibrations coming from the engine compartment which I can feel throughout the cabin and the steering wheel. These vibrations end abruptly when I accelerate past 2k rpm, and I can hear a "wooshing" sound from the engine, as if some compartment from the engine is being enabled/disabled. It is audible on the outside of the car also. I can feel a reasonably strong hiccup in the car when this occurs, and this occurs numerously through the drive while switching gears at varying speeds.... I've gathered from the other thread this might be from the engine disabling/enabling cylinders? I don't know anything about cars, but I get the feeling this isn't quite normal. Or is it?

Also, there is a fast chirping noise coming from the engine when accelerating....

I get the noticable vibrations (only noticable at low speeds) and the slightly different sound (more pronounced "humming" sound) from the engine when the car is in 2-cylinder mode.

 

I can't say I have

- the "wooshing" nor

- the "strong hiccup" nor

- the "fast chirping noise" (I get a whining noice when accelerating hard but that sounds like the "normal" turbo sound and it is not always audiable, ie when audiable it is very low)

 

You can see whether the car is in 2-cylinder mode by selecting to show information about the real time fuel consumption in the display area in the digital instrument cluster. After doing so a text (something like "2-cylinder mode") will be displayed in the display area when the engine is in 2-cylinder mode. I'm not sure but you might not even need to select to show the real time fuel consumption as another indication of when the 2-cylinder mode is active is when an encircled "Eco" symbol is shown in the display area.

Edited 17 November, 20223 yr by SiWaiting
correction

On 17/11/2022 at 10:56, SiWaiting said:

I get the noticable vibrations (only noticable at low speeds) and the slightly different sound (more pronounced "humming" sound) from the engine when the car is in 2-cylinder mode.

 

I can't say I have

- the "wooshing" nor

- the "strong hiccup" nor

- the "fast chirping noise" (I get a whining noice when accelerating hard but that sounds like the "normal" turbo sound and it is not always audiable, ie when audiable it is very low)

 

You can see whether the car is in 2-cylinder mode by selecting to show information about the real time fuel consumption in the display area in the digital instrument cluster. After doing so a text (something like "2-cylinder mode") will be displayed in the display area when the engine is in 2-cylinder mode. I'm not sure but you might not even need to select to show the real time fuel consumption as another indication of when the 2-cylinder mode is active is when an encircled "Eco" symbol is shown in the display area.

I don't have any information on the dashboard about which cylinder mode the engine is in. Searched everywhere. No eco symbols either.

Well I've driven around 10k km with it since I bought it (used at 15k km) and it hasn't gotten worse so... Not sure if these are "features" of the car or I should be worried.

Hiccup is there when accelerating, and engine switches from 2 cylinder to 4 cylinder.

@PilsnerUrquel set your VC to show fuel consumption on one of the dials. There you should get info if it switched to 2 cylinder mode. Observe if symptoms you are describing are showing when in 2 cylinder mode.

Most probably this is the case.

4 hours ago, PilsnerUrquel said:

I don't have any information on the dashboard about which cylinder mode the engine is in. Searched everywhere. No eco symbols either.

Well I've driven around 10k km with it since I bought it (used at 15k km) and it hasn't gotten worse so... Not sure if these are "features" of the car or I should be worried.

Do you have the Analogue instrument cluster? I don't know if the analogue instrument cluster can show information about 2-cylinder mode. I have the Digital instrument cluster. Read about information clusters under "Driver information system" in the Owners Manual.

Edited 20 November, 20223 yr by SiWaiting

23 minutes ago, SiWaiting said:

Do you have the Analogue instrument cluster? I don't know if the analogue instrument cluster can show information about 2-cylinder mode. I have the Digital instrument cluster. Read about information clusters under "Driver information system" in the Owners Manual.

I have the digital cluster and there's definitely no 2-cylinder indication whatsoever. The eco icon comes on when the DSG is coasting out of gear, that's about it. Then again, I have the 1.5 TSI G-Tec, not sure if the CNG version uses 2-cylinder mode, although I strongly suspect it does.

1 hour ago, SiWaiting said:

Do you have the Analogue instrument cluster? I don't know if the analogue instrument cluster can show information about 2-cylinder mode. I have the Digital instrument cluster. Read about information clusters under "Driver information system" in the Owners Manual.

I have the analogue indeed.

4 hours ago, Felix2021 said:

Hiccup is there when accelerating, and engine switches from 2 cylinder to 4 cylinder.

@PilsnerUrquel set your VC to show fuel consumption on one of the dials. There you should get info if it switched to 2 cylinder mode. Observe if symptoms you are describing are showing when in 2 cylinder mode.

Most probably this is the case.

Is it normal you can hear this on the outside of the car? When the engine switches cilinder modes?

I don't know to be honest.

Maybe you should just report it under warranty? It's really hard for us, on the forum, to give you definite answer if we haven't heard it.

From your description i would suspect it's 2 cylinder mode, but i cannot be 100% sure.

Search for "2 cylinder mode skoda" or "act octavia" on youtube and you'll find several examples of Analogue instrument cluster showing the "2-cylinder mode"-text, for example https://www.youtube.com/watch?v=3aR_Gw5M3kE

You should now know where to look if you've got an engine with cylinder deactivation.

 

How do I actually know if my octavia has ACT? Because for all I know it doesn't have it. It doesn't say so on Skoda Connect either, just the Skoda Octavia 1.5 TSi Ambition.

And if it doesn't have ACT, is it still switching cilinders? Or do they all come with ACT nowadays?

Edited 20 November, 20223 yr by PilsnerUrquel

All petrol 1.5 TSI's are ACT as far as i know.

17 hours ago, Jorgeminator said:

Then again, I have the 1.5 TSI G-Tec, not sure if the CNG version uses 2-cylinder mode, although I strongly suspect it does.

 

I suspect not (unfortunately only second hand sources but enough to question whether the G-tec has cylinder deactivation) :

 

- "In contrast to the gasoline engine of the same size, the TGI dispenses with cylinder deactivation..." https://topgear-autoguide.com/category/compact/vw-golf-15-tgi-bluemotion-in-the-test1607804099

- Haven't found that VW mentions ACT, ACM or cylinder deactivation in their marketing material regarding the TGI, e.g . https://www.volkswagen-newsroom.com/en/press-releases/now-available-with-natural-gas-drive-again-pre-sales-of-the-new-golf-tgi-underway-6514

- At auto-data.net the "1.5 TSI EVO (150 Hp)" has "Cylinder deactivation system" under "Engine systems" but the "1.5 TGI G-TEC (130 Hp) CNG" doesn't https://www.auto-data.net/en/skoda-octavia-iv-1.5-tgi-g-tec-130hp-cng-38028

First hand source confirming that the G-tec does not have cylinder deactivation:

 

 

 

3 hours ago, SiWaiting said:

First hand source confirming that the G-tec does not have cylinder deactivation:

 

 

 

Thanks, very helpful!

I wonder if they compensate for the lack of ACT by using the Miller cycle to increase the CR, since the G-Tec is mighty efficient on the highway 🤔 I've done 2.5kg/100km or ~4 l/100km quite a few times.

Edited 21 November, 20223 yr by Jorgeminator

16 hours ago, PilsnerUrquel said:

How do I actually know if my octavia has ACT? Because for all I know it doesn't have it. It doesn't say so on Skoda Connect either, just the Skoda Octavia 1.5 TSi Ambition.

And if it doesn't have ACT, is it still switching cilinders? Or do they all come with ACT nowadays?

Mine have ACT, but it is not mentioned in Skoda Connect APP. It is the 1.5 eTSI