• Hi Guest we, are working on an upgrade to the forum this week, meaning the service may be unreliable at times and there will be some planned downtime at some point. Stay updated on this thread.
  • Guest, 🚨New Stock alert: Premium CUPRA valve caps now available in the store 👉 Order now from the merchandise store

Leon FR 1.4 2014 stutters at 4k rpm

Decimator

Active Member
Mar 22, 2025
14
2
Hi lads new here just recently purchased a manual 1.4 Leon FR 2014 having an issue when accelerating hard the power just cuts suddenly at 4k rpm and stutters all the way to 5 two cylinder mode seems to be activating any suggestions on how to stop this
 

Decimator

Active Member
Mar 22, 2025
14
2
Hi lads thanks for getting back just been busy, ran dieptain through it and injector cleaner changed coil packs and plugs, cleaned map sensors still no look, no codes and no miss fires logged I'm a bit lost with this now there's 145k Kms on the clock
 

Mr Pig

Active Member
Jun 17, 2015
2,925
1,094
You say two-cylinder more is activating, how do you know? Is the tell-tale light on the dash activating under acceleration? Shouldn't be. It should only activate when the engine is under very low load. As soon as you ask for power it should switch back to four cylinders and you shouldn't feel the transition at all.

I don't know the ins and outs of the system but it's very finely tuned. You need special kit to replace the timing belt and typically only dealers and VAG specialists have it. If an independent garage changed the timing belt assuming it's just like any other car it's possible they didn't get it right and the system is not working correctly. Check the service record. If Joe Blogs changed that belt I think I'd be taking the car to a dealer or VAG specialist to have the ACT system checked.

I would suggest faulty injectors too but I can't see that putting the ACT light on.
 
  • Like
Reactions: Decimator

Decimator

Active Member
Mar 22, 2025
14
2
You say two-cylinder more is activating, how do you know? Is the tell-tale light on the dash activating under acceleration? Shouldn't be. It should only activate when the engine is under very low load. As soon as you ask for power it should switch back to four cylinders and you shouldn't feel the transition at all.

I don't know the ins and outs of the system but it's very finely tuned. You need special kit to replace the timing belt and typically only dealers and VAG specialists have it. If an independent garage changed the timing belt assuming it's just like any other car it's possible they didn't get it right and the system is not working correctly. Check the service record. If Joe Blogs changed that belt I think I'd be taking the car to a dealer or VAG specialist to have the ACT system checked.

I would suggest faulty injectors too but I can't see that putting the ACT light on.
Yeah the light is activating but it's not all the time which is confusing me I've also just realised I can't hear the diverter valve opening I had a look at the actuator rod there's a bit of play in it and when I rev the car and let off it's not opening but I'm also not getting surge back through the turbo. And yes the timing belt was done but that was at 100k Kms. I bought the car from a garage so I do have warranty on it but not for long I will be going back to him with it. Should I go to a seat dealer first and ask them to have a quick look?
 

Mr Pig

Active Member
Jun 17, 2015
2,925
1,094
Yeah the light is activating but it's not all the time which is confusing me I've also just realised I can't hear the diverter valve opening I had a look at the actuator rod there's a bit of play in it and when I rev the car and let off it's not opening but I'm also not getting surge back through the turbo. And yes the timing belt was done but that was at 100k Kms. I bought the car from a garage so I do have warranty on it but not for long I will be going back to him with it. Should I go to a seat dealer first and ask them to have a quick look?
The ACT light does come on and off. It just depends when. It should only come on under very light load. As soon as you press the accelerator it should go out.

The actuator rod on the turbo does have play on it, it's supposed to be like that. They can stick. My son's stuck. Worked some high-temp grease into it and it's been fine since. I don't know if that could cause your symptoms but worth checking.

From my experience, dealers are not very good at fault finding. Anything much outside of routine maintenance and they're stumped. I'd be inclined to trust an independent VAG specialist more.
 
  • Like
Reactions: nd-photo.nl

Decimator

Active Member
Mar 22, 2025
14
2
The ACT light does come on and off. It just depends when. It should only come on under very light load. As soon as you press the accelerator it should go out.

The actuator rod on the turbo does have play on it, it's supposed to be like that. They can stick. My son's stuck. Worked some high-temp grease into it and it's been fine since. I don't know if that could cause your symptoms but worth checking.

From my experience, dealers are not very good at fault finding. Anything much outside of routine maintenance and they're stumped. I'd be inclined to trust an independent VAG specialist more.
Ah grand I'll have a look for one so thanks for the reply
 

BlackFR

Full Member
Jan 22, 2002
1,727
7
Not too far away
You definitely aren't alone on this one.i replaced the actuator and greased the mechanism with high temp grease. Sadly it made no difference.

I'm now ruminating carbon build up being the cause.


I don't suppose you have found any more info in the last month or so?
 

Mr Pig

Active Member
Jun 17, 2015
2,925
1,094
From what I've read intake fouling can be an issue from as low as 60K onward. My car's over 80K and still running perfectly and getting good MPG but expect I could encounter this any time now. What's your millage BlackFR? I don't know the symptoms of intake fouling but it wouldn't surprise me if this is one of them.

The best cleaning method seems to be walnut blasting. It costs around £400 and works well. There are people who offer to spray solvent into the intake but it's ineffective. The deposits are too hard and have to be physically removed either by walnut blasting or scraping them off by hand.

It's not something to ignore as it's possible that when it gets bad enough the valves can stick open and very bad things happen.

As an aside, I've seen using premium fuel mentioned multiple times as a way of delaying intake fouling but that make zero sense. Direct injection puts petrol straight into the cylinder, does not wash over the intake valves so cannot help to clean them. If you've got fuel in the intake of a direct injection car something is very wrong! ;0)
 
  • Like
Reactions: RUM4MO

BlackFR

Full Member
Jan 22, 2002
1,727
7
Not too far away
I'm on about 84k at the moment, i popped some pictures of the valves on mine in the thread I linked above. They are pretty gummed up!

I phoned around a few local places and they all want £1k+ for walnut blasting unfortunately, just not worth it at that price.

Cable ties in a drill to agitate the carbon and some solvent seems to be a recommended home brew fix up.

I was just hoping someone else with the problem had actually managed to get a fix.
 

Mr Pig

Active Member
Jun 17, 2015
2,925
1,094
I phoned around a few local places and they all want £1k+ for walnut blasting unfortunately, just not worth it at that price.
Yeah, it's a problem as cars get older. Some maintenance tasks become a big chunk of what the car is worth. My wife wants to keep her car, forever I think, so whatever it needs I just get it.
 
Jun 20, 2025
4
5
Hi lads new here just recently purchased a manual 1.4 Leon FR 2014 having an issue when accelerating hard the power just cuts suddenly at 4k rpm and stutters all the way to 5 two cylinder mode seems to be activating any suggestions on how to stop this
Did you ever get to the bottom of this? I'm having the exact same problem on my 2015 ST with the same engine, no eml and no stored or pending codes, revs fine in first gear but stutters when revved over 4000rpm in second gear, haven't tried 3rd gear, there's always somebody in front. Just bought the car 30 days ago from a dealer who haven't been very responsive since I reported it to them a week ago so had my usual garage scan for codes but he couldn't do more without booking it in for next week.

I may be best trying to find a VAG specialist near to me.
 

Decimator

Active Member
Mar 22, 2025
14
2
Did you ever get to the bottom of this? I'm having the exact same problem on my 2015 ST with the same engine, no eml and no stored or pending codes, revs fine in first gear but stutters when revved over 4000rpm in second gear, haven't tried 3rd gear, there's always somebody in front. Just bought the car 30 days ago from a dealer who haven't been very responsive since I reported it to them a week ago so had my usual garage scan for codes but he couldn't do more without booking it in for next week.

I may be best trying to find a VAG specialist near to me.
Yeah ended up sorting it self It was just injectors took about 2 bottles of injector cleaner to sort it threw a third one in after just to be sure don't know why the 2 cylinder mode was activating when this was happening but haven't had any problems since no codes for my self either stored on vcds. Id say give the injector cleaner a go and maybe a bottle of dieptain
 
  • Like
Reactions: TheGOW and Mr Pig

Mr Pig

Active Member
Jun 17, 2015
2,925
1,094
Yeah ended up sorting it self It was just injectors took about 2 bottles of injector cleaner to sort it...
The first thing that comes into my head when I read that is supermarket fuel.

Yes, the base fuel is the same but premium fuel contains additive packs which help to keep your fuel system and engine clean. Quality control of the whole process is just tighter. Over the years I've seen so many issues caused by supermarket fuel. They insist it's the same quality as branded fuel but it's not. That's why it's cheaper.

Just last week a friend told me his car's engine light came on immediately after his wife filled the car with supermarket fuel. He went on to his local Facebook group and found that loads of other people in the area were reporting exactly the same thing! My bet would silicone contamination and gubbed O2 sensors.
 
  • Like
Reactions: RUM4MO

RUM4MO

Active Member
Jun 4, 2008
8,136
1,136
South Scotland
As consumers we really should be getting better protection from what can really be "duff" products - like certain supermarket fuels that don't have industry level types and/or quantities of additives in them.
Nothing new in this so there has been plenty time for governments to look into this as the BS spec etc only relates to the base fuel - which most people should know, is not by itself suitable for most engines designed and built over the past maybe 40 years.
I remember that when my older daughter started in high school/secondary school, so maybe 30 years ago, one of her friend's father was the service manager for a local Vauxhall garage - when the first big supermarket opened up near that workshop, within 6 months they had to start expanding their facilities and staff due to the increase in demand for "engine issues", that was Sainsburys but I suppose it could have been any of them. I also remember when Asda sold Esso fuels at a very good price, then as time went on, the Esso signage vanished but the "Esso" colour scheme remained - a bit naughty, they knew what they were doing!
I have been using Costco for petrol both for UL for the 2015 Polo 1,2TSI and UL+ for my 2011 Audi S4 - and also use UL+ 2 or 3 times a year in the Polo, I seem to remember that the signage on the pumps, did at least for some time, point out that their fuels DID clean the back of the intake valves - well not for DI petrol engines!!

Edit:- I mean, supermarket own brand baked beans only affect your body's food intake as does their version of breakfast cereals - but that does not cause permanent long term damage, these supermarket fuel can and sometimes do cause permanent damage though the extent of that really depends on the actual engine type and brand.
 
  • Like
Reactions: Mr Pig

Decimator

Active Member
Mar 22, 2025
14
2
The first thing that comes into my head when I read that is supermarket fuel.

Yes, the base fuel is the same but premium fuel contains additive packs which help to keep your fuel system and engine clean. Quality control of the whole process is just tighter. Over the years I've seen so many issues caused by supermarket fuel. They insist it's the same quality as branded fuel but it's not. That's why it's cheaper.

Just last week a friend told me his car's engine light came on immediately after his wife filled the car with supermarket fuel. He went on to his local Facebook group and found that loads of other people in the area were reporting exactly the same thing! My bet would silicone contamination and gubbed O2 sensors.
Id say your right about that I also think that the car was left sitting for a good while as the tyres on it are quite old and front and backs are the same year so I'd say that didn't help it either not being driven
 

Mr Pig

Active Member
Jun 17, 2015
2,925
1,094
Id say your right about that I also think that the car was left sitting for a good while..
Yeah, also not good. If nothing else, petrol degrades over time and modern stuff with that ethanol crap in it is worse. Just Run it for a while with good fuel and I think you'll be fine.

I use high octane about 70% of the time. I think it does make a difference.
 
  • Like
Reactions: Decimator

cuthound

Active Member
Jan 26, 2024
74
56
The first thing that comes into my head when I read that is supermarket fuel.

Yes, the base fuel is the same but premium fuel contains additive packs which help to keep your fuel system and engine clean. Quality control of the whole process is just tighter. Over the years I've seen so many issues caused by supermarket fuel. They insist it's the same quality as branded fuel but it's not. That's why it's cheaper.

Just last week a friend told me his car's engine light came on immediately after his wife filled the car with supermarket fuel. He went on to his local Facebook group and found that loads of other people in the area were reporting exactly the same thing! My bet would silicone contamination and gubbed O2 sensors.

The supermarket fuel think is I think an urban myth.

I live close to the Kingsbury Fuel Terminal https://www.eetfuels.com/our-locations/kingsbury-terminal/

Until about three years ago you could see tankers with every conceivable branding (supermarkets, Jet, Murco, etc, and premium brands) queueing up to fill from the same tanks. A neighbour who is an ADR qualified tanker driver confirmed the only difference was that the "pots" (tanker compartments) that were going to have premium high octane fuels, were dosed with an additive prior to filling with the same standard fuel.

Then suddenly most of the tankers became Hoyer branded tankers, apparently according to my neighbour, because too many drivers were becoming aware that there was little or no difference between brands, only between premium and standard fuel.