Excess carbon buildup inside intake manifold and on injectors

[gebaracuda]

Hello there,

Is it pretty common to have too much carbon deposit on the air inlets and in this part of the engine? My car has just reached 100k and I already changed set of injectors due to too much carbon deposit. I was told that this is a basic issue with these engines, given that I make sure to use 98 octane everytime. I don't push the car to high rpm often, only on few occasions during the week, so I am not sure if this is making the problem worse.

My mk7 GTi is a 2014 model. If anyone can shed some light on this issue, it will be great. At least I will know if it's a normal thing or not.

Thanks,
Og

 

[daconchslop]

DI motors are notorious for carbon buildup. 100k sounds about right for a cleaning.
Is your car a ROW model with factory MPI?

 

[jimlloyd40]

Hello there,

Is it pretty common to have too much carbon deposit on the air inlets and in this part of the engine? My car has just reached 100k and I already changed set of injectors due to too much carbon deposit. I was told that this is a basic issue with these engines, given that I make sure to use 98 octane everytime. I don't push the car to high rpm often, only on few occasions during the week, so I am not sure if this is making the problem worse.

My mk7 GTi is a 2014 model. If anyone can shed some light on this issue, it will be great. At least I will know if it's a normal thing or not.

Thanks,
Og

I would do carbon cleaning every 50,000 miles. It's the back side of the valves that get the most carbon buildup. Higher octane fuel doesn't help at all because the fuel doesn't hit the back side of the valves. I don't understand how carbon buildup can happen on the injectors with fuel coming out of them. Were the injectors replaced for a different reason?

 

[gebaracuda]

I would do carbon cleaning every 50,000 miles. It's the back side of the valves that get the most carbon buildup. Higher octane fuel doesn't help at all because the fuel doesn't hit the back side of the valves. I don't understand how carbon buildup can happen on the injectors with fuel coming out of them. Were the injectors replaced for a different reason?

Two of the injectors got clogged in a span of 6 months approximately. One I guess just got to the end of it's life, but the second one actually had the needle stuck inside as I had really slammed the pedal across all the gears. It was the first time I actually pushed it to the max on sport mode. As I slowed down, it started misfiring and jolting when I pressed on it again. I had it towed to the dealer. Upon inspection, they told me the needle got stuck inside which resulted in the injector staying open and flooding the combustion chamber.

But to go back to what you were saying, yes the carbon sets mostly in the back side of the valves. But strangely, the tip of the injectors had some gunk on them. How they got there, I'm not sure. But overall, I was really surprised by how much carbon this engine collects. I find it very strange that such a well built engine would have such a flaw in it.

So basically the injectors main defect is the excess carbon.

 

[gebaracuda]

DI motors are notorious for carbon buildup. 100k sounds about right for a cleaning.
Is your car a ROW model with factory MPI?

It's Middle Eastern specs.. pretty much like European but with a stronger AC And yes, it is still factory settings.. Haven't done any mods yet.
I know that 100k sounds about right, but really surprised by the amount of buildup there was.. wish I took a photo. I wasn't sure if a change of injectors is a normal step at this point. I felt it's too early on this engine.

 

[Reggie Enchilada]

Sounds like you need to run it harder, more often. No joke, VW found that most of the carbon deposits on the valve stems will get burned off if you keep the RPM above 3.5k-4k for 20-30 minutes and get the valve stems heated up. It's actually listed in their patent for the EA888 engine. Someone posted a link to it on here before. You'll still get some buildup due to the nature of the DI system, but it should help some. Another thing that you can do would be to run a bottle of fuel system cleaner through it every few tanks.

 

[daconchslop]

Good old Italian tune ups.
I was also going to ask if you regularly do short trips where the motor doesn’t really spend much time at normal op temps.
Also sounds like Middle East specs doesn’t come with factory port injection either. It’s a good idea to run a fuel system cleaner every couple of tanks or so. Do you fuel up from the same place?

 

[jimlloyd40]

Two of the injectors got clogged in a span of 6 months approximately. One I guess just got to the end of it's life, but the second one actually had the needle stuck inside as I had really slammed the pedal across all the gears. It was the first time I actually pushed it to the max on sport mode. As I slowed down, it started misfiring and jolting when I pressed on it again. I had it towed to the dealer. Upon inspection, they told me the needle got stuck inside which resulted in the injector staying open and flooding the combustion chamber.

But to go back to what you were saying, yes the carbon sets mostly in the back side of the valves. But strangely, the tip of the injectors had some gunk on them. How they got there, I'm not sure. But overall, I was really surprised by how much carbon this engine collects. I find it very strange that such a well built engine would have such a flaw in it.

So basically the injectors main defect is the excess carbon.

Your injectors didn't have carbon buildup. You just need to use an injector cleaner in your fuel tank occasionally.

And carbon buildup on the back side of the valves is a problem with all gas direct injection engines. It's not inherent to VW.

 

[gebaracuda]

Sounds like you need to run it harder, more often. No joke, VW found that most of the carbon deposits on the valve stems will get burned off if you keep the RPM above 3.5k-4k for 20-30 minutes and get the valve stems heated up. It's actually listed in their patent for the EA888 engine. Someone posted a link to it on here before. You'll still get some buildup due to the nature of the DI system, but it should help some. Another thing that you can do would be to run a bottle of fuel system cleaner through it every few tanks.

You're right.. I think I need to run it harder more often. Running a bottle of injector cleaner will do no harm as well. They usually do that at the dealership during service, but I guess that's not enough.

Thanks buddy

 

[gebaracuda]

Good old Italian tune ups.
I was also going to ask if you regularly do short trips where the motor doesn’t really spend much time at normal op temps.
Also sounds like Middle East specs doesn’t come with factory port injection either. It’s a good idea to run a fuel system cleaner every couple of tanks or so. Do you fuel up from the same place?

Yup, short trips most of the time. Got the same feedback from you all regarding the fuel system cleaner.. will definitely be putting more of that. Yeh I'm pretty consistent with the fuel.. the same petrol station every time. I think the car just needs to be pushed harder a bit more often. But with speed cameras everywhere mostly on my commute, makes it more difficult. Gotta find a way

Thanks anyway

 

[gebaracuda]

Your injectors didn't have carbon buildup. You just need to use an injector cleaner in your fuel tank occasionally.

And carbon buildup on the back side of the valves is a problem with all gas direct injection engines. It's not inherent to VW.

I just hope I won't have to face this issue frequently. The key word here I guess is injector cleaner. That should tick the box on several other issues as well.

Thanks Jim

 

[daconchslop]

Maybe also consider fuel quality and change up the station.

 

[jimlloyd40]

I just hope I won't have to face this issue frequently. The key word here I guess is injector cleaner. That should tick the box on several other issues as well.

Thanks Jim

The fuel injector cleaner will obviously help with the injectors but not the carbon buildup on the valves.

 

[gebaracuda]

I found this video to be helpful.. as well as the link that's under. That's a scary sight..

https://www.shopdap.com/blog/carbon-build-up-and-cold-start-misfires-on-2-0t-tsi.html/

 

[Reggie Enchilada]

You don't even have to run it that hard. Just go for a drive on a highway at 3500rpm's for about 30 minutes every now and then