Hi guys, long winded query but wondering if anybody has had the same issue and if so how it was resolved. I have a Skoda Octavia estate on a 2020 plate. It recently had the timing belt changed and since then I have had some issues, I no longer think it is the timing belt replacement that caused it, as this has been checked by three different garages, I think it is a coincidence that the issue started at the same time. Basically my vehicle isn't giving out any fault codes and this has been confirmed with Skoda level diagnostics, however since this time when I am idling I would describe it as rough idling and every now and again when I am stationery I can hear a loud put put out noise, this is intermittent and has unfortunately not done it when I have taken it to the garage. The original mechanic has washed his hands of me as he has decided there is nothing wrong with it after replacing coil pack 2 & spar plugs, and blames the fact that I have a three cylinder engine, even though it didn't do this noise prior to him doing the timing belt etc. The second garage did all the diagnostics but unfortunately seem to be led by the machine and as it's given no fault code don't know what to do with it. So I therefore took it to an engine tuning specialist who has hooked it up to another machine and although it has shown no faults there are sub menu, that have shown I have a 1000 moisture in my catalytic converter (due a run but also numerous mechanics having it idling recently) and also that there are misfires on all 3 cylinders around the 1500 Mark. He asked me where I put my fuel in and what fuel I use, to which I advised that I fill it up at Sainsbury's on my way to work and use E10. This mechanic has diagnosed that he thinks it is a fuel issue and to be honest I didn't even know that E10 was a newer fuel, its kinda snuck up on me at the petrol station. Having checked my handbook I think although it is compatible with both E5 and E10 it appears that Skoda recommend E5 and a fuel of 98 ron or above and therefore he has added some fuel tank cleaner and some injector cleaner into my fuel tank and since then, after running it a bit, I have refueled it with a full tank of shell v power. It is still doing the noise although I think it is less and I am hoping that after a couple more tanks the issue is resolved but as anyone else had this issue and if so did it rectify after a few tanks of fuel or do I need to be looking at replacing some parts?

You mention 3 cylinders and timing belt, what engine do you have?

Just a 1.0 litre

It's fine 27000 miles

Se drive 115 tsi

Could be so many things, diagnostics does end (or even begin often) with error codes or lack of them, it can take a fair bit to alert the extremely dumb computer systems well passed what a driver/owner might detect as something wrong. Live data should help which the engine tunning specialist should have picked up and has made a suggestion on.

Has the car been sitting around unused for a time.

One tank refill isn't going to clear things out if that's required it'll take two or three tank fulls (not top-ups) at least to notice any improvement. Once you have the engine full warmed 90+C oil temperature then give the car a good long Italian-tune-up run on a longer distance journey, very high speed not necessary but keep sensibly higher revs (which will be well away from 1500 rpm) that will blow things through and warm the exhaust. A few of those runs might start to clear things out more and help get through the higher octane E5 petrol with extra cleaning additives. What's the point of having the 115(?) if you're not going to use the extra power occasionally

27,000 miles in 5 years isn't a lot perhaps it's clogged up a bit from too many short journeys(?).

Make sure your engine air filter and its box and tubes are clean, replace the engine air filter if it wasn't changed with the spark plugs or a little time before. Are you sure the plugs were the correct one as you only has three any issue with just one of them is a whole third instead of quarter (or less).

For E5 higher octane petrol with additional cleaning additives I'd stick with Tesco Moment99 or Shell V-Power but there are others, see attached old and out of date list for some of them. - petrol.pdf

Edited 17 August, 202517 Aug by nta16
yupo

Thanks so much for your reply. All my friends are adamant it's must be something to do with the timing but the mechanics are saying not and it's more coincidental.

It hasn't been stood and unused but admittedly it only does 8 miles each way to work and back.

I'm going on holiday tomorrow but when I get back I will do a few junctions up the motorway....and carry on with the V power for a bit before heading back to the tuning guy.

It's had a service every year but I don't know what filters they replace. Again, I know the plugs were done with the coil pack but I didn't see what they were. Allegedly he did them at the service at same time as the cam belt etc but then had to do them again with the coil pack. I'll get the tuning guy to check them when and if I take it back.

But I appreciate your advice that it will need a few tank fulls, as I suppose that was what I was asking, before deciding to take it back. My sister is going to have use of it while I'm away so it won't be stood

Why was the timing belt changed?

Running a few tankful's of V-power with some Italian tune-up runs is far cheaper than visiting an engine tuner normally. Is the car standard or have you had it tweaked. There's no substitute for road running, you can see and record data in real world circumstances rather than on rollers.

You don't need motorways to do Italian tune-ups just keep the revs up sensibly high, nice bendy roads with gear changes are fine, motorways are sooooo boring.

Below is an old out of date VWŠkoda showing the scant minimal "servicing" and "maintenance schedules" , perhaps Air-con service is too regular but other stuff like engine air filter interval seems too stretched to me and the "service" cover a bit of the engine but not rest of the car. A lower mileage car would need an annual engine oil and filter change probably more than a higher than average mileage car. 8 miles should just about get the engine oil to temperature towards the middle to end of the journey but not perhaps for the majority of the journey and if it's all low mph and rev driving it's hardly giving the car systems much exercise.

There may be more than one issue or cause to this issue, perhaps one is as your friends say timing, or it's only the timing but what checks and equipment do you friends have to confirm their thoughts.

Also never assume just because parts are new that they can't be the wrong or faulty parts or fitted wrong or partly wrong, has the correct coil been changed (did the coil even need changing) the tuner said the misfire was on all three cylinders.

Perhaps you could run the petrol tank very low (panic level) and see if things get worse. Then you can more fully refill with fresh E5 petrol and give the whole car more exercise.

Tell your sister once she has the engine full warmed, 90+C oil temperature, to then give the car a good long Italian-tune-up run on a longer distance journey, very high speed not necessary but keep sensibly higher revs, have some fun with the 115(?)PS, after all it's not her petrol she's using. 😁

Enjoy your holiday.

3 hours ago, nta16 said:

Why was the timing belt changed?

There is no reason to change the timing belt on a 2020 car in 2025 - whoever advised it is way out of date since Skoda UK finally got in line with the rest of the VAG empire a while back and scrapped the ridiculous 5 year interval.

I know that now ...but first mechanic didn't say anything when I booked it in...I've always had it drummed in to do at 5 year's....infact it used to be 3. But bit late now as it's done, and not sure that is the cause of the current issue.

11 hours ago, nta16 said:

Why was the timing belt changed?

Running a few tankful's of V-power with some Italian tune-up runs is far cheaper than visiting an engine tuner normally. Is the car standard or have you had it tweaked. There's no substitute for road running, you can see and record data in real world circumstances rather than on rollers.

You don't need motorways to do Italian tune-ups just keep the revs up sensibly high, nice bendy roads with gear changes are fine, motorways are sooooo boring.

Below is an old out of date VWŠkoda showing the scant minimal "servicing" and "maintenance schedules" , perhaps Air-con service is too regular but other stuff like engine air filter interval seems too stretched to me and the "service" cover a bit of the engine but not rest of the car. A lower mileage car would need an annual engine oil and filter change probably more than a higher than average mileage car. 8 miles should just about get the engine oil to temperature towards the middle to end of the journey but not perhaps for the majority of the journey and if it's all low mph and rev driving it's hardly giving the car systems much exercise.

There may be more than one issue or cause to this issue, perhaps one is as your friends say timing, or it's only the timing but what checks and equipment do you friends have to confirm their thoughts.

Also never assume just because parts are new that they can't be the wrong or faulty parts or fitted wrong or partly wrong, has the correct coil been changed (did the coil even need changing) the tuner said the misfire was on all three cylinders.

Perhaps you could run the petrol tank very low (panic level) and see if things get worse. Then you can more fully refill with fresh E5 petrol and give the whole car more exercise.

Tell your sister once she has the engine full warmed, 90+C oil temperature, to then give the car a good long Italian-tune-up run on a longer distance journey, very high speed not necessary but keep sensibly higher revs, have some fun with the 115(?)PS, after all it's not her petrol she's using. 😁

Enjoy your holiday.

Thanks for all that.

The belt was changed as I thought it had to be a certain intervals and my last car was 5 years.

Anyway another mechanic said it didn't need to be that frequently anymore, but what's done is done...I won't need to do it again as I'm getting a new one in 4 years.

I'll carry on with the V power and take it from there!

The VW Website and the recommendation for 98 ron was for GTI,s / R,s and was from before the UK had no retailers selling 98 ron. It went 97 or 99 ron min over a decade ago.

The Skoda cars that had prescribed 98 ron were the Fabia Mk2 vRS, and before that the Octavia.

If there are Skoda / VW recent published advice on Super Unleaded and use 98 ron or higher please link it.

So anyway.

Euro 6 1.0 TSI,s. 3 cylinder, with a misfire. Even if no fault codes logged as not enough in a cycle.

Check the spark plugs. 1 is prone to premature failure.

A failing plug can cause a ignition coil to fail. Simples stuff. & as to 1.0 TSI timing belts. Too many messed those up not using the correct tool.

PS

The crap AI puts out on fuel is unreal.

Much based on the USA or Rest of World and Octanes. Or EU / Europe not UK in Europe were 97 ron E5 is Super Unleaded. or 99 Ron Min. 100-102 or higher is sold as race fuel.

Sainsbury E5 Super unleaded shown as 97 ron is good stuff and can be 97 or 99 ron min depending on who is delivering and in which part of the UK. They buy at best price @ the time and that might be from Greenergy. Producers of Tesco Momentum 99 and ESSO Synergy 99 in some parts of the UK.

Edited 18 August, 202518 Aug by Ootohere

Different car to a Fabia and without the benefit(?) of all the computer control (or even single or multiple let alone TSI) but with my old car I always found BP Ultimate to be noisy and old Esso 0% to be smoothest. I forgot Sainsburys as I never go there but my wife has used their 97 in the Fabia particularly if the price is good.

@Ootohere you are regularly up to date with petrols why not update the list and add Sainsburys.

Edited 18 August, 202518 Aug by nta16
typos

The fuel filler flap used to, as well as tyres, give petrol info - and with a book symbol refer you to the 'Owner's manual' for more info.

Yeah mine says both E5 and E10.....i got the manual out last week and says at least 95 Ron but pref 98.....

14 minutes ago, nta16 said:

The fuel filler flap used to, as well as tyres, give petrol info - and with a book symbol refer you to the 'Owner's manual' for more info.

1 minute ago, Linzifc said:

Yeah mine says both E5 and E10.....i got the manual out last week and says at least 95 Ron but pref 98.....

97-99 petrols will be E5 (up to 5% ethanol) with higher cleaning additive packages so try running on only those and see if things improve give all else that you done already. Tesco Momentum99 is still my favourite or V-power if it's not too expensive or same for Esso, you may find differently with your car but I'd be a bit more surprised if you did.

Some say all petrols are the same, and all oils are the same, they are to a point but there are differences in both, sometimes not much difference but some difference which can be very important in some circumstances.

I'm not a fan of 4-cylinder VW engines (always sounded rough to me and I'm used to 1960 and 70s BL engines!) so to lose a cylinder means even more care and attention required. I've had under 700cc turbo engines but they were Japanese (better engineering than VW) and one Merc which was excellent much against the expensive new Mercs of that time which were poor, German marques decline, worse now of course.

Bit late to this thread but it is possible to slightly muck up cam timing without doing catastrophic damage to the engine.

That said with all the short journeys it could just be the engine needs a good run on good fuel.

Other possibility is that it needs a carbon clean assuming that injectors, coil packs and sparkplugs all ok.

Thanks.....I think if it doesn't resolve shortly I'll take it back to the engine tuning guy with those suggestions. Thanka again!

Just a small point re Skoda & VW Group and fuel filler flaps and 'Super Unleaded' as they call it in Germany or where ever.

The Fabia Mk2 vRS fuel filler where 95 is the Minimum and 98 Recommended / Prescribed.

'Super plus'.

Same with GTI,s / R,s and Cupra etc, and people will know if their vRS has the same. (95) / 98.

Nearly all modern engines will make use of a better grade of fuel automatically. They nearly all have sophisticated knock detection and will advance the ignition accordingly.

The major reason for not using E10 is the water it absorbs if left in the tank for a longish time. Hence the constant advice to use E5 if you do low mileage.

As an aside, never use E10 if you have petrol powered garden tools. It'll spell early death for them.

Hello, I have an update on the misfire for the car & wondered if you guys had heard of such a thing. I got back off holiday & the car was getting noisier. I messaged the tuning guy who said he couldn't fit me in for at least 2weeks. As I was getting concerned it was something to do with the timing &possibly causing damage to the car I went back to the previous garage, who hadn't found any issues on the diagnostics machine.They are a large local firm and are dealer level but I don't want to name them on here. they looked at it yesterday & put it back on the diagnostics machine and found the information the tuning guy had pointed out about the moisture in the cat & all three cylinders misfiring, there was a discussion & they suggested it could possibly just be the spark plugs (as they were changed at the same time as the timing belt). After they checked the spark plugs, even though they are not Skoda ones they confirmed that bosch ones have been used & that they were fully compatible& should cause no issues. They then stripped the car down & said that the timing was perfect and that the previous mechanic had done this correctly. They then started investigating other aspects. They phoned me a couple of hours later & told me that they thought they had fixed it & that it was my software that was really out of date in the ECU (this was really out of date because the car is a 2020 model & i have never heard such a thing as updating it) it's been for regular services I've had no information from Skoda that this is anything that I should ever do?? The garage updated all of the software and apparently messed with other certain settings and was happy that the issue was fixed, They took it for a test drive hooked up to the machine and it has stopped misfiring, therefore he is reset all that information. I picked the car up at a cost of £480, purely for five hours labour. Drove it home & tbh all the way home it didn't do the poppin sound at all so I was really confident that they had actually fixed it and it was something as silly as the ecu which was stopping the car from performing correctly (& coincidentally happening at same time as the belt change) however I stopped to pick up my dog from the dog walker & when I got back in the car it did it again. so I've come home & haven't been out in it since. I need to spend some time over the weekend just seeing whether it is fixed or not. My issue is it's not fixed & i a really don't know what to do from here. it had been in for a service it had an MOT & I did the timing belt (with it being five years old) spark plugs were changed. because of the noise starting, the first mechanic decided it could be a coil pack, so did coil pack 2 and another set of plugs. The noise was right from the beginning from getting it back after the MOT etc. second garage who was my friends dad who didn't have the time to carry out any work but he took one look and said it was the timing. The third garage (which was the dealer level garage) put it on the machine and as it gave no fault codes said was nothing wrong. The tuning guy in fairness to him started at the beginning asking me about my fuel I put in the shell v power & the cleaning products but it got nosier.

Personally i think the blind are leading the blind.

The timing belt might well be the issue as with many who never used the tool and locked the engine correctly.

Edited 6 September, 20256 Sep by Ootohere

4 hours ago, Linzifc said:

Hello, I have an update on the misfire for the car & wondered if you guys had heard of such a thing. I got back off holiday & the car was getting noisier. I messaged the tuning guy who said he couldn't fit me in for at least 2weeks. As I was getting concerned it was something to do with the timing &possibly causing damage to the car I went back to the previous garage, who hadn't found any issues on the diagnostics machine.They are a large local firm and are dealer level but I don't want to name them on here. they looked at it yesterday & put it back on the diagnostics machine and found the information the tuning guy had pointed out about the moisture in the cat & all three cylinders misfiring, there was a discussion & they suggested it could possibly just be the spark plugs (as they were changed at the same time as the timing belt). After they checked the spark plugs, even though they are not Skoda ones they confirmed that bosch ones have been used & that they were fully compatible& should cause no issues. They then stripped the car down & said that the timing was perfect and that the previous mechanic had done this correctly. They then started investigating other aspects. They phoned me a couple of hours later & told me that they thought they had fixed it & that it was my software that was really out of date in the ECU (this was really out of date because the car is a 2020 model & i have never heard such a thing as updating it) it's been for regular services I've had no information from Skoda that this is anything that I should ever do?? The garage updated all of the software and apparently messed with other certain settings and was happy that the issue was fixed, They took it for a test drive hooked up to the machine and it has stopped misfiring, therefore he is reset all that information. I picked the car up at a cost of £480, purely for five hours labour. Drove it home & tbh all the way home it didn't do the poppin sound at all so I was really confident that they had actually fixed it and it was something as silly as the ecu which was stopping the car from performing correctly (& coincidentally happening at same time as the belt change) however I stopped to pick up my dog from the dog walker & when I got back in the car it did it again. so I've come home & haven't been out in it since. I need to spend some time over the weekend just seeing whether it is fixed or not. My issue is it's not fixed & i a really don't know what to do from here. it had been in for a service it had an MOT & I did the timing belt (with it being five years old) spark plugs were changed. because of the noise starting, the first mechanic decided it could be a coil pack, so did coil pack 2 and another set of plugs. The noise was right from the beginning from getting it back after the MOT etc. second garage who was my friends dad who didn't have the time to carry out any work but he took one look and said it was the timing. The third garage (which was the dealer level garage) put it on the machine and as it gave no fault codes said was nothing wrong. The tuning guy in fairness to him started at the beginning asking me about my fuel I put in the shell v power & the cleaning products but it got nosier.

Have you checked for cracked hoses around the inlet manifold, PCV valve etc, it might be worth replacing the PCV valve, not very expensive, I think, did anyone check the manifold depression while idling, could be fault with brake servo.

Thanks ....I don't know what they are but I'll tell them next week!