Interesting fault smokes when eco mode switches off help please. Updated.šŸ™

Mr Pig

Active Member
Jun 17, 2015
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It was a tough choice.. we know the cylinder had no compression after it failed and in the past the plug on 3 on got oily regularly so changed an injector which seemed to cure the wet/contaminated plug. Back then we did a compression test and all cylinders were fine.
I have an idea of what might have been wrong.

These engines are direct injection so you do not have fuel washing over the intake valves to keep them clean. The valves getting gummed up is a known issue with direct injection. The bigger VW engines use a combination of direct and port injection to avoid it. It's very possible that you suffered a stuck valve due to a buildup of crap on it.

It's tricky. My car is running fine, it's at 65K miles now, but I'm thinking about getting the intake cleaned as a precaution. I may take some stuff off and get a borescope in there to see what it looks like but I don't know how bad the buildup has to be before it's likely to cause a problem.
 

MA1601

Active Member
Jan 3, 2023
29
10
I have an idea of what might have been wrong.

These engines are direct injection so you do not have fuel washing over the intake valves to keep them clean. The valves getting gummed up is a known issue with direct injection. The bigger VW engines use a combination of direct and port injection to avoid it. It's very possible that you suffered a stuck valve due to a buildup of crap on it.

It's tricky. My car is running fine, it's at 65K miles now, but I'm thinking about getting the intake cleaned as a precaution. I may take some stuff off and get a borescope in there to see what it looks like but I don't know how bad the buildup has to be before it's likely to cause a problem.
Would be interesting to see your findings and also if any other high mileage 1.4 tsi ACT engines have had this issue.
 

Mr Pig

Active Member
Jun 17, 2015
2,628
910
Would be interesting to see your findings and also if any other high mileage 1.4 tsi ACT engines have had this issue.
I've not heard of any.

I knew about the potential for this issue when I bought the car. I was expecting to be looking at having the intake cleaned by now, 65K miles, and I looked into the cleaning process years ago. Walnut shell blasting looks promising.

I was expecting to see some mild signs of fouling,like reduced economy or lack of power, but that has got me slightly worried that the first indication of trouble might be more serious. I don't know if it's an interference engine, most are, and if so a stuck valve could be catastrophic.
 

SuperV8

Active Member
May 30, 2019
1,344
594
I've not heard of any.

I knew about the potential for this issue when I bought the car. I was expecting to be looking at having the intake cleaned by now, 65K miles, and I looked into the cleaning process years ago. Walnut shell blasting looks promising.

I was expecting to see some mild signs of fouling,like reduced economy or lack of power, but that has got me slightly worried that the first indication of trouble might be more serious. I don't know if it's an interference engine, most are, and if so a stuck valve could be catastrophic.
Certainly, a stuck valve would be hitting the piston!
 

Mr Pig

Active Member
Jun 17, 2015
2,628
910
Certainly, a stuck valve would be hitting the piston!
Yip, something I've experienced before.

But what do you do? How can you predict when it might happen without removing the intake to look? And when do you do that?

The annoying thing is that there is nothing you can do to prevent this. Better fuel or cleaners won't help as it goes in after the valves. You could dump cleaner down the intake while it's running but you don't know if it's worked without removing the intake. It's not a very clever design.
 

SuperV8

Active Member
May 30, 2019
1,344
594
Yip, something I've experienced before.

But what do you do? How can you predict when it might happen without removing the intake to look? And when do you do that?

The annoying thing is that there is nothing you can do to prevent this. Better fuel or cleaners won't help as it goes in after the valves. You could dump cleaner down the intake while it's running but you don't know if it's worked without removing the intake. It's not a very clever design.

This is an interesting video:
85,000 miles worth of build up!
from this thread:

Personally If I had a petrol DI engine I would be factoring in an inlet cleaning preventative maintenance every 50-60k miles.
 

Mr Pig

Active Member
Jun 17, 2015
2,628
910
Good video. Nice to know that blasting stuff down the intake will not work. Shame, as it's cheap!

I'm going to look around and see if there is anyone locally who does this sort of cleaning. There is a small performance garage in Falkirk who I spoke to before. They seem to know what they're doing and they were up for it.
 
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Jason2023

Active Member
Jul 13, 2023
39
13
All good points. When the mechanic was swapping the engines over on taking the inlet manifold off he noticed my failed engine had a lot more carbon than the donor engine on the valves. The replacement engine has 61 k miles old engine 99k miles. Iā€™ve read somewhere the only cleaning method is manual, but no mileage guidelinesā€¦.
 

Jason2023

Active Member
Jul 13, 2023
39
13
This is an interesting video:
85,000 miles worth of build up!
from this thread:

Personally If I had a petrol DI engine I would be factoring in an inlet cleaning preventative maintenance every 50-60k miles.
I agree just had my valves inspected when the engine swap took place, all ok not much build up, but I will get them checked in about 50 k ish time.
 
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Jason2023

Active Member
Jul 13, 2023
39
13
I've not heard of any.

I knew about the potential for this issue when I bought the car. I was expecting to be looking at having the intake cleaned by now, 65K miles, and I looked into the cleaning process years ago. Walnut shell blasting looks promising.

I was expecting to see some mild signs of fouling,like reduced economy or lack of power, but that has got me slightly worried that the first indication of trouble might be more serious. I don't know if it's an interference engine, most are, and if so a stuck valve could be catastrophic.
 
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