On 06/09/2025 at 06:50, Linzifc said:

I put in the shell v power & the cleaning products but it got nosier

That should be a coincidence given you are in a 2020 modern car with all of its remoteness for the driver from the car with sound insulation, infotainments and computer systems. You would need to go through a couple of tankfuls, not x-gallons or x-litres (depending on your age) for the fuels to have any real accumulated difference -so either go through a couple of tankfuls of higher octane fuel with additional cleaner additives and lower ethanol or go back to a couple of tankfuls of lower octane fuels with less cleaner additives and higher ethanol and see if it gets worse, better or no difference. I'd chose the former.

The garages and tuner should have picked up any air leaks with their diagnosis and scanners on live running data - but that's the same for timing errors or if wrong coil pack was changed or spark plug issues.

The engines (and cars) are run by computer so who knows what errors and "glitches" are in heir programming but they still run mechanical and electrical bit which can be faulty or damaged (or not made right).

The fact that you drove home without the popping may suggest something needs to accumulate, or get warm or move to reintroduce the issue so note this and tell whoever is next to look at the car. Unfortunately you do see reports of several looking at a vehicle until someone right, or just lucky, looks at it and sorts the issue (unless it's a car, component or manufacturer issue either not known or acknowledged, yet or ever.

It's a very frustrating and expensive process but do bear in mind it's only a car, a lump of metal and plastic and it could be sorted and might even turn out to be something simple previously missed or not showing. Good luck.

If it started again there should be new fault codes. As to induction leaks, ask the garage if they do a smoke test. If they don't then ask them how they find induction leaks.

5 minutes ago, nta16 said:

That should be a coincidence given you are in a 2020 modern car with all of its remoteness for the driver from the car with sound insulation, infotainments and computer systems. You would need to go through a couple of tankfuls, not x-gallons or x-litres (depending on your age) for the fuels to have any real accumulated difference -so either go through a couple of tankfuls of higher octane fuel with additional cleaner additives and lower ethanol or go back to a couple of tankfuls of lower octane fuels with less cleaner additives and higher ethanol and see if it gets worse, better or no difference. I'd chose the former.

The garages and tuner should have picked up any air leaks with their diagnosis and scanners on live running data - but that's the same for timing errors or if wrong coil pack was changed or spark plug issues.

The engines (and cars) are run by computer so who knows what errors and "glitches" are in heir programming but they still run mechanical and electrical bit which can be faulty or damaged (or not made right).

The fact that you drove home without the popping may suggest something needs to accumulate, or get warm or move to reintroduce the issue so note this and tell whoever is next to look at the car. Unfortunately you do see reports of several looking at a vehicle until someone right, or just lucky, looks at it and sorts the issue (unless it's a car, component or manufacturer issue either not known or acknowledged, yet or ever.

It's a very frustrating and expensive process but do bear in mind it's only a car, a lump of metal and plastic and it could be sorted and might even turn out to be something simple previously missed or not showing. Good luck.

Thanks for that. Yes I thought after taking it out yesterday that it happened after it got warm on those two occasions, so I think he's made it better but not fully cured it. I'll see what they are suggesting tomorrow about going forward and costings..or I could wait for the tuning guy to be free.

My main concern for getting it was checked was to make sure it wasn't the timing. They've stripped it down and said it's perfect so why it started now I have no idea. We just use this car for holidays with it being an estate and I'm anxious about breaking down if it's anything major. I suppose they can recheck the misfiring numbers as he reset them Friday. And I do have breakdown cover. I was seriously thinking about trading it in yesterday but I dont see why I should after 27000 miles! Plus it then becomes someone else's issue.

1 hour ago, Aldfort said:

If it started again there should be new fault codes. As to induction leaks, ask the garage if they do a smoke test. If they don't then ask them how they find induction leaks.

It hasn't shown any fault codes to date ....

There were some background menus that they showed me which showed misfiring and moisture on the cat if that's what you mean....I will get them to recheck the misfires this week. Thanks for your advice.....they gonna hate me tomorrow when I reel off all this stuff!

The Moisture in the Catalytic Converter interests me.

Sounds like BS.

Not possible to have moisture in the catalytic converter. I think he might be referring to the rear exhaust silencer.

7 minutes ago, PaulTT said:

Not possible to have moisture in the catalytic converter. I think he might be referring to the rear exhaust silencer.

Not sure....I saw the machine he showed me and it said 1000.

I'm taking it back in shortly so they can check any misfires on the machine since they reset it on Friday.....

My friends dad says he can try squeeze it in to do a compression test but I'll let the original guys I've paid re check it first while they not charging me.....

The cat should be heating up quickly and any misfires or Software / Engine management issues might cause issues.

Does the engine start with a RPM at about 1,100 rpm and drop to around 800-850 after 40-60 seconds running?

No AC on?

If the car sits around unused for weeks or months that may not help and not help the car generally in some respects.

8 hours ago, Ootohere said:

The cat should be heating up quickly and any misfires or Software / Engine management issues might cause issues.

Does the engine start with a RPM at about 1,100 rpm and drop to around 800-850 after 40-60 seconds running?

No AC on?

Yes re the rpm. Well maybe that was a separate issue and he fixed that's with the ECU update?

4 hours ago, nta16 said:

If the car sits around unused for weeks or months that may not help and not help the car generally in some respects.

Yeah it doesn't. I use it everyday...I do 8 miles each way to work minimum. I know it needs a good run every now and then. I tend to drive lower gear high revs too....

So it went back to the guys who did the ECU software updates Fri - and rechecked the spark plugs and timing belt (from them being done by the first mechanic).

Today's verdict is that the cam shaft has been slightly damaged when doing the belt....the opposite end to where the belt goes ...as it's only slight damage that is why it's running and not showing any major fault codes. And why the tool fits in where it should at the other end.

So apparently you can't get just the rod bit for my car and I'd need a full unit at £1500 plus 5 hours labour.

Though he was saying when questioned that He also couldn't make any guarantees and if it doesn't fix it I still have to pay.

So I'm just gonna drive it and turn the radio up 🤷

On 08/09/2025 at 12:19, Ootohere said:

The cat should be heating up quickly and any misfires or Software / Engine management issues might cause issues.

Does the engine start with a RPM at about 1,100 rpm and drop to around 800-850 after 40-60 seconds running?

No AC on?

Mine is doing like that. Is that an issue?

2 minutes ago, MAKAKI said:

Mine is doing like that. Is that an issue?

The RPM thing or the problem I'm describing with my Octavia??

Starting at 1,100 rpm and dropping within a minute is not an issue.

For some staying at a high RPM is. Caused because of GPF,s. Various threads on here cover that issue.

On cold start it is around 1100-1200 rpm but in 50-60 sec it goes down to 800-900 rpm. My engine is 1.2 HTP 70 HP CGPA.

2 hours ago, MAKAKI said:

On cold start it is around 1100-1200 rpm but in 50-60 sec it goes down to 800-900 rpm. My engine is 1.2 HTP 70 HP CGPA.

Sounds like a perfectly normal cold start to me.