Carbon build-up in DI engines

DCNISMO · 07-26-2014, 08:21 AM

Seems to have found the actual cause, and catch cans and meth really don't work…

Turbo Fuel Stratified Injection (TFSI) & Direct Port Injection Carbon Build-up Problem | Oilem - Lifting the lid on the market

Thats why I won't buy a car with DI till the figure it out...

N8GTOL · 07-26-2014, 11:28 AM

Good informative article. Thanks for sharing as I was not aware of this issue.

DLSTR · 07-28-2014, 07:02 AM

This is a problem for the GTi I own but its not a world ending problem. The RS4's of Audi in 2006 etc had major problems as well as the early R8 4.2's. If you have a Mk6 GTi like I do you will need to clean this around 60-100k miles. Sucks overall but its not that big a deal. There are ways to mitigate this by driving with higher revs occasionally but nothing can prevent it at all. Seafoam nothing.
Quite a few cars are affected but changes to injection design have been made especially by VW to prevent this.

FlyByGTI · 07-28-2014, 07:49 AM

As DLSTR said, this is definitely an issue with the GTI platform (I had it in mine). The only way that I've found, by researching it, to avoid the build up was to really get on it. VW actually recommends driving their DI cars above 3k for long periods of time (at least 20 minutes) each time you drive the car to help avoid buildup. There are many people I know who will actually stay in 5th vs 6th on the highway to work to help keep it down. Problem is that once you get that build up, you're pretty much stuck and need to clean the valves. As weird as it sounds, CLR worked wonders with really pulling that build up off.

Essentially if you go DI, just make sure you actually drive it like it should be driven and that should keep you from having to do valve cleanings for longer periods of time.

RoshDawg · 07-28-2014, 08:07 PM

Sorry officer. I was just cleaning my valves...

DCNISMO · 07-28-2014, 10:42 PM

For a long time Audi and VW said there was not a problem and did not want to cover it under warranty. So the guys that popped 80K for a RS4 had to pay for valve cleaning on their own. Audi did some crappy BG induction service and a ECU reflash that failed miserably. To me spending that amount of money on a car and it not being covered, is why I'm out of the Audi scene.

FlyByGTI · 07-29-2014, 08:24 AM

Quote:

Originally Posted by DCNISMO

For a long time Audi and VW said there was not a problem and did not want to cover it under warranty. So the guys that popped 80K for a RS4 had to pay for valve cleaning on their own. Audi did some crappy BG induction service and a ECU reflash that failed miserably. To me spending that amount of money on a car and it not being covered, is why I'm out of the Audi scene.

The reason they won't cover it is because it is "normal maintenance" that is supposed to happen on the vehicle

Mitco39 · 07-29-2014, 09:11 AM

Diesels have been direct injected right from the start. Why do they not see this sort of thing happening? Its the same systems (EGR, PCV) on both engines.

Water injection could be used to keep them clean no?

The Bimmer world uses Walnut blasting.

REVIEW: Cleaning of intake valves with BMW walnut shell blasting tool

FlyByGTI · 07-29-2014, 09:17 AM

Quote:

Originally Posted by Mitco39

Diesels have been direct injected right from the start. Why do they not see this sort of thing happening? Its the same systems (EGR, PCV) on both engines.

Water injection could be used to keep them clean no?

The Bimmer world uses Walnut blasting.

REVIEW: Cleaning of intake valves with BMW walnut shell blasting tool

I think it might have something to do with the way you are supposed to drive a diesel. I believe you are supposed to be driving them at high RPMs from the very beginning of their life, which is going to keep the carbon build up to a minimum is done properly

I may be misinformed on that though

Mitco39 · 07-29-2014, 09:36 AM

Quote:

Originally Posted by FlyByGTI

I think it might have something to do with the way you are supposed to drive a diesel. I believe you are supposed to be driving them at high RPMs from the very beginning of their life, which is going to keep the carbon build up to a minimum is done properly

I may be misinformed on that though

You got it backwards. Modern pickup diesels like to run anywhere from 1600rpm to 2200rpm. Most red line or have rev limters around 3500rpm.

Thinking about this after I posted it thought it could have something to do with the higher boost keeping the gunk from sticking. Mind you at cruise a diesel only sits around 2-5PSI.

FlyByGTI · 07-29-2014, 10:02 AM

Quote:

Originally Posted by Mitco39

You got it backwards. Modern pickup diesels like to run anywhere from 1600rpm to 2200rpm. Most red line or have rev limters around 3500rpm.

Thinking about this after I posted it thought it could have something to do with the higher boost keeping the gunk from sticking. Mind you at cruise a diesel only sits around 2-5PSI.

I guess that would make sense. I didn't really know about the truck aspect of it, but was thinking about it from the point of view of smaller diesels (ie. Golf TDI).

Never owned a diesel so I don't really have a huge abundance of knowledge with them.

Mitco39 · 07-29-2014, 10:05 AM

Quote:

Originally Posted by FlyByGTI

I guess that would make sense. I didn't really know about the truck aspect of it, but was thinking about it from the point of view of smaller diesels (ie. Golf TDI).

Never owned a diesel so I don't really have a huge abundance of knowledge with them.

Im just curious as to what causes this to be an issue here but yet you can have a diesel with 500K miles and the valves will look ok (not good, but not coated like that picture by any means). Maybe there ports are designed in such a way to speed up the air entering the cylinder so that the air moves much faster around the valve? I know for a fact that the EGR systems on a diesel are way way more messy than that of a gas engine. All that soot goes into the intake tract. If you could find the difference between the two I think you would be well on your way to a solution. For all we know it could even just be a special coating on the valves.

FlyByGTI · 07-29-2014, 11:26 AM

Quote:

Originally Posted by Mitco39

Im just curious as to what causes this to be an issue here but yet you can have a diesel with 500K miles and the valves will look ok (not good, but not coated like that picture by any means). Maybe there ports are designed in such a way to speed up the air entering the cylinder so that the air moves much faster around the valve? I know for a fact that the EGR systems on a diesel are way way more messy than that of a gas engine. All that soot goes into the intake tract. If you could find the difference between the two I think you would be well on your way to a solution. For all we know it could even just be a special coating on the valves.

Looking around it seems like there are a few things with the Diesel direct injection that are interesting. Apparently the biggest issue facing those engines is idling. The recommendation (and this may explain why cummins drivers seem like d-bags all the time), is that to combat the build up in diesel engines you should floor it 10-15 times a drive. Apparently the way that the EGR is setup, it closes during full fuelling which means that flooring it should blast away all the crud and gunk. It doesn't seem like the Gas Direct Injection has that same setup on them. It looks like the smaller displacement turbo cars should have an easier time avoiding carbon buildup because they are more likely under heavy load for longer periods of time.

Limeybastard · 07-29-2014, 11:54 AM

This is the inherent issue with DI, my previous platform the Mazdaspeed was DI also.

Mitco39 · 07-29-2014, 01:15 PM

Quote:

Originally Posted by FlyByGTI

Looking around it seems like there are a few things with the Diesel direct injection that are interesting. Apparently the biggest issue facing those engines is idling. The recommendation (and this may explain why cummins drivers seem like d-bags all the time), is that to combat the build up in diesel engines you should floor it 10-15 times a drive. Apparently the way that the EGR is setup, it closes during full fuelling which means that flooring it should blast away all the crud and gunk. It doesn't seem like the Gas Direct Injection has that same setup on them. It looks like the smaller displacement turbo cars should have an easier time avoiding carbon buildup because they are more likely under heavy load for longer periods of time.

Thats not entirely true. I have seen the inside of diesel engines on farm trucks driven by old farmers with nothing out of the ordinary in terms of build up. I mean you always will have some but nothing to affect performance a noticeable amount or anything like that. Surely nothing like that picture. I suggest deleting the external EGR where ever possible, its just not a good setup. Most new cars just have a internal EGR by changing the cam degrees with respect to each other.

I bet if there was a way to turn this off on the Z you would see both fuel mileage and power gains from it. The Z does not have external EGR system on it, so it only leads me to believe it is controlled by the VVEL.

07-26-2014, 08:21 AM	#1 (permalink)
DCNISMO Track Member Join Date: Nov 2011 Location: washington dc Posts: 995 Drives: Nismo Z Rep Power: 178	Carbon build-up in DI engines Seems to have found the actual cause, and catch cans and meth really don't work… Turbo Fuel Stratified Injection (TFSI) & Direct Port Injection Carbon Build-up Problem \| Oilem - Lifting the lid on the market Thats why I won't buy a car with DI till the figure it out...

07-28-2014, 07:02 AM	#3 (permalink)
DLSTR A True Z Fanatic Join Date: May 2011 Location: Süd Germany Posts: 2,462 Drives: 21Supra 2.0/22 M240i Rep Power: 21266	This is a problem for the GTi I own but its not a world ending problem. The RS4's of Audi in 2006 etc had major problems as well as the early R8 4.2's. If you have a Mk6 GTi like I do you will need to clean this around 60-100k miles. Sucks overall but its not that big a deal. There are ways to mitigate this by driving with higher revs occasionally but nothing can prevent it at all. Seafoam nothing. Quite a few cars are affected but changes to injection design have been made especially by VW to prevent this. Last edited by DLSTR; 07-28-2014 at 08:49 AM.

07-28-2014, 07:49 AM	#4 (permalink)
FlyByGTI Base Member Join Date: Jun 2014 Location: Pittsburgh Posts: 231 Drives: 09 370z Sport Rep Power: 10	As DLSTR said, this is definitely an issue with the GTI platform (I had it in mine). The only way that I've found, by researching it, to avoid the build up was to really get on it. VW actually recommends driving their DI cars above 3k for long periods of time (at least 20 minutes) each time you drive the car to help avoid buildup. There are many people I know who will actually stay in 5th vs 6th on the highway to work to help keep it down. Problem is that once you get that build up, you're pretty much stuck and need to clean the valves. As weird as it sounds, CLR worked wonders with really pulling that build up off. Essentially if you go DI, just make sure you actually drive it like it should be driven and that should keep you from having to do valve cleanings for longer periods of time. __________________ Slow and steady is winning this race...

07-28-2014, 08:07 PM	#5 (permalink)
RoshDawg Track Member Join Date: May 2011 Location: NM / CA Posts: 981 Drives: '13 911 C2S Rep Power: 14	Sorry officer. I was just cleaning my valves... fuct likes this. __________________ \| EVO X MR \| '11 WRX STI \| 370Z SPRT \| 911 (991) C2S \|

07-28-2014, 10:42 PM	#6 (permalink)
DCNISMO Track Member Join Date: Nov 2011 Location: washington dc Posts: 995 Drives: Nismo Z Rep Power: 178	For a long time Audi and VW said there was not a problem and did not want to cover it under warranty. So the guys that popped 80K for a RS4 had to pay for valve cleaning on their own. Audi did some crappy BG induction service and a ECU reflash that failed miserably. To me spending that amount of money on a car and it not being covered, is why I'm out of the Audi scene. fuct likes this.

07-26-2014, 11:28 AM	#2 (permalink)
N8GTOL Base Member Join Date: May 2010 Location: San Diego Posts: 228 Drives: and flies Rep Power: 21	Good informative article. Thanks for sharing as I was not aware of this issue.

07-29-2014, 09:11 AM	#8 (permalink)
Mitco39 A True Z Fanatic Join Date: Aug 2012 Location: Edmonton Alberta Canada Posts: 2,089 Drives: 40th 370z Rep Power: 131	Diesels have been direct injected right from the start. Why do they not see this sort of thing happening? Its the same systems (EGR, PCV) on both engines. Water injection could be used to keep them clean no? The Bimmer world uses Walnut blasting. REVIEW: Cleaning of intake valves with BMW walnut shell blasting tool __________________ 2007 Chevy Duramax - EFILive Tuned By Me 2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her My Build --> http://www.the370z.com/members-370z-...39s-build.html

07-29-2014, 11:54 AM	#14 (permalink)
Limeybastard A True Z Fanatic Join Date: Apr 2014 Location: FL and London UK. Posts: 1,514 Drives: 2014 370Z Sport. Rep Power: 17	This is the inherent issue with DI, my previous platform the Mazdaspeed was DI also.

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