Hi all, I recently bought a 2012 octavia with the 1.2 tsi 105 hp engine, it has 235000km but drives good.
The only issue I have is that when I give it some heavy gas when the rpm is 1500-2000 it feels like the engine hesitates a bit and has small inconsistency in power delivery (more noticeable on higher gears acceleration), also I can feel the car shake a tiny bit when it idles.
My mom has a 2013 octavia with the same powertrain and much less miles so Im familiar with how the car should feel.
I have read that the ignition coil or the ignition leads (typically cylinders 3 and 4) could fail, how can I test them to be sure that they cause the issue and not just throw money on new parts that maybe didnt need to be replaced?
Im good with carbureted engines (as my profile picture would suggest) but not so much with new cars.
Thanks in advance.

Look at the leads and see if they are upgraded with armour around them. Especially cylinder 3. Are the Spark plugs all good with the correct gap? Best get it read for Fault Codes and see if there are any logged for mis-fires.

Edited 11 December, 202511 Dec by Evolution13

16 minutes ago, Evolution13 said:

Look at the leads and see if they are upgraded with armour around them. Especially cylinder 3. Are the Spark plugs all good with the correct gap? Best get it read for Fault Codes and see if there are any logged for mis-fires.

Yes they have the armour around them, they are even ziptied so I guess they have been previously replaced.

I still havent checked the sparkplugs so it will be a task for the weekend.

I would have a new set ready to fit if you do not have a service history for the plugs being changed.

Probably a good idea to replace plugs anyway and see if it makes any difference plus you then know plugs are good. If it doesnt improve get the car scanned for misfires etc. Someone on here will know the best most reliable make.

Alasdair

Something went bad, I tried today to replace the spark plugs but my socket (16mm) would not fit because the plugs have a rubber boot on them (maybe from the spark leads?)

this is how the 1 and 2 spark leads look like (1 on the left, 2 on the right):

So I connected them back because i couldnt remove the spark plugs but then a random misfire started (Im almost sure from cylinder 1 because I put my ear near the engine and everytime a misfire happened there was a click (probably a short?) coming from the 1st spark plug.
I went for a small drive and if I put some load on the gas pedal the car shakes and cant output power at all, I need to give it a gentle gas to drive smoothly.
I tried to connect and disconnect the number 1 spark lead several times and still no difference.
The only thing I did to the engine is to disconnect and connect 1 and 2 spark leads, can it be that the number 1 lead is failing?

Update:

After a long hour that broke my back I managed to remove the rubber boots that got stuck on plugs 1 and 2, then I removed and inspect them and they seem ok (I have seen worse, I was so stressed that I didnt buy new ones because I just wanted to fix the mess I made).

Then I bought new spark wires that cost about 75$.

After replacing the 1 and 2 spark wires the car ran great and after a short drive I think it even fixed the original problem I had with it.

Interesting thread this for me, as I've had a similar problem with Fabia 1.2 TSi and had to replace the ignition leads like you have.

I'm wondering if that rubber on spark plug one is something that's been left on from a previous spark plug or lead change and maybe if you'd got that off and replaced the leads all would have been good.

I know that when I was replacing my plugs, the rubber insert inside my 16mm plug socket would always stay on the plug terminal and I had to use long pliers to retrieve it; it's possible that could be what the rubber piece left on you No 1 plug was.

In my case, 3 of the 4 metal sockets inside the ignition leads broke off and were left on the spark plugs.

Did you use a special tool to remove the metal ignition lead boots?