Can I use the seafoam spray on the N14?
Placing the red tube in the boost tube?
Or should I use the liquid one thru the vacuum hose?

 

any particular reason for attempting it? I've never gotten measurable results from any Seafoam spray or liquid.

 

I have read many people using seafoam with good results.
Not sure if my valves are gummed up but at 43k miles I believe it is time for some cleaning.

 

The only way to really clean valves is a blasting.

 

Detroit Tuned recommends doing it every 10k miles, but J Free is right that a walnut blasting is the only true cure.

Here's a video of someone doing it:

 

You can clean them manually by hand. Brushes, carb cleaner and so on. Seafoam won't do anything but lighten your wallet on a direct injection engine. And there is no effective way to get it into the ports to clean the valves. I've cleaned my intakes twice now and the exhausts once manually. Results are perfectly acceptable for a cost of around $50.

 

I suppose I am the sort of person who needs to see data. Now, I'm not in a place where I can see the video posted but I'm willing to bet there was some smoke / fumes coming out of the exhaust there. People see it and think, "wow, sure must be doing something with all that smoke going on" To me, that has no value. I've yet to see a study backed by anything other than a butt dynamometer showing an improvement, especially with direct injection.
My skepticism aside, Has your car began to run sluggishly? Just because it's got 40k+ miles on it doesn't necessarily mean it's built up. If you've been putting quality fuel in, and appropriately changing oil, you're not likely to see a benefit.
If it is "feeling down" then I'd say you could have something worth looking in to.

 

My question is regarding the form of application.
On the video the guy uses the liquid version, pouring it to the vacuum line.
With the spray version of sea foam you place the spray nozzle in the boost tube and spray it for 5 minutes. There is a video I saw but I cannot find it.
The spray version is recommended for the N18 and the liquid for the N14.
Why can´t (should not) I spray into the boost tube on my N14? Can the throttle body get damaged or something else?