# FSI Carbon Build Up Removal Benefits: Fact or Fiction



## defector (Nov 26, 2000)

*FSI Intake Port Carbon Build Up Removal Benefits: Fact or Fiction?*

http://forums.vwvortex.com/showthre...efits-Fact-or-Fiction&p=77567119#post77567119 

Opinions welcome. That is all that this is.....an opinion. 

Jim


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## bostonaudi1 (May 14, 2006)

Cleaning the valves is a waste of time. You're better off spending the time trying to wash your cat. 

Why? IMO its a waste for several reasons. 1) unless you can somehow stop the cause of the buildup, you haven't fixed anything, it will be gunked up again a week later. 2) as you observed there is no performance gain. It's a turbocharged motor, air will get rammed through regardless of a bit of gunk on the valves. 

So clean away if it makes you feel better, I'll be out on the road driving (with my dirty gunked up valves!). 

OTOH, dirty injectors are another matter.


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## Bill6211789 (Dec 11, 2009)

bostonaudi1 said:


> Cleaning the valves is a waste of time. You're better off spending the time trying to wash your cat.
> 
> Why? IMO its a waste for several reasons. 1) unless you can somehow stop the cause of the buildup, you haven't fixed anything, it will be gunked up again a week later. 2) as you observed there is no performance gain. It's a turbocharged motor, air will get rammed through regardless of a bit of gunk on the valves.
> 
> ...


 how come after cleaning my valves do i see better MPG's? best i could see before valve cleaning was 27.xx MPG's now im in the 30s


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## dmorrow (Jun 9, 2000)

bostonaudi1 said:


> Cleaning the valves is a waste of time. You're better off spending the time trying to wash your cat.
> 
> Why? IMO its a waste for several reasons. 1) unless you can somehow stop the cause of the buildup, you haven't fixed anything, it will be gunked up again a week later. 2) as you observed there is no performance gain. It's a turbocharged motor, air will get rammed through regardless of a bit of gunk on the valves.
> 
> ...


 If it took 100k miles for them to get gunked up would it take about as long for it to happen again? I would assume that if you waited a week and took it apart it wouldn't look the same as when before you cleaned them. I think you could use the "I'm going to get dirty again so what's the point" as a way to justify never taking a shower also. 

Also, it seems like a lot of time was taken to optimize the size of the valves and make sure it had smooth walls leading to the chamber, none of this mattered? 

On the other hand, I am at 127k miles and have never had it cleaned. I do rarely have some cold start problems but probably won't keep the car more than another year and have debated having it done (cost/benefit ratio is debatable).


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## jpawl (Apr 12, 2000)

bostonaudi1 said:


> Cleaning the valves is a waste of time. You're better off spending the time trying to wash your cat.
> 
> Why? IMO its a waste for several reasons. 1) unless you can somehow stop the cause of the buildup, you haven't fixed anything, it will be gunked up again a week later. 2) as you observed there is no performance gain. It's a turbocharged motor, air will get rammed through regardless of a bit of gunk on the valves.
> 
> ...


 Waste of time? How else does one get rid of the idle misses (when cold) that trips the CEL? 

Thanks, 

Jim


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## kplo (Jun 1, 2012)

just want to throw in my opinion since I just cleaned the intake valves last weekend. The symptom on my car (2007 A3) is the persistent P0302 code, which is cylinder 2 misfire. I first replaced the obvious (spark plugs and coils). While I was replacing the plugs, I found that the recess for coil #1 and #2 to go in were filled with engine oil. Suspecting that was caused by the valve cover gasket leaking, I replaced the gasket as well. CEL was off for 2 days and then came back on. I read about the carbon build-up issue but I dragged my feet on doing it since it is a time-consuming task. CEL remained on and the misfire became so bad that even my wife can feel the car was running rough and lacking power. I don't want to damage the cat. converter so I bite the bullet and took up the task. There are LOTS of gunk in there. All the photos of carbon build-up on the web are true and representative. Mine was particularly bad at cylinder #2 and #3. Since misfire can also be due to faulty injector, I swapped injector #2 and #3 while I had everything opened (and yes, I did reseal the injectors). It has been a week now and no more CEL, car is running smooth. 

So I would definitely say carbon build-up is true on the FSI (probably so for all direct injection engines for that matter). Is it always the reason for misfire and other issues? I am not sure. But it seems like this is the culprit for my P0302 issue. And since I have tried the other troubleshooting routes, this is the logical next step for me. Some may argue it could be the injectors. But since I need to remove the exact same number of parts in order to replace the injectors, why not clean the valves also while you are at it. The only thing I should have done was to swap coils before replacing all of them with new ones since those are obviously not the root cause. 

Sorry for the long post, but the last thing that I want say is that some people seem to misunderstand why carbon build-up is a problem. VW themselves acknowledged this in their patent. Click the link below if you are interested in learning more. For the impatient, go to the description section and read the "background of the invention" section. 

http://www.google.com/patents?id=fLITAAAAEBAJ&zoom=4&pg=PA14#v=onepage&q&f=false


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## jbyronr (Jul 27, 2001)

I cleaned my BPY valves 10,000 miles ago at 90k. Almost no improvement in fuel economy or drivability since. Driving wasn't identical, but the rolling average before valve cleaning was 23.6mpg and the average since has been 23.8mpg. 
As an Audi tech, I've seen FSI valve cleaning fix cold start misfires, but my car didn't have that issue. 

The roof rack I use has a much bigger effect on MPG (~1.5mpg in the more expensive direction) . That of course includes driving with a bike and a kayak for various trips, often enough that it's worth keeping the rack installed 

I had hoped and believed the valve cleaning would do more, but for me, it did not. 
Maybe it is preventing a future cold start issue, but I won't know. 

I do oil changes every 5k miles, and use top-tier gas almost exclusively. My cams were very clean, but the valves were just as dirty as my customers who use crap gas and change the oil only when the car reminds them to every 10k.


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## blackvento36 (Mar 17, 2003)

bostonaudi1 said:


> Cleaning the valves is a waste of time. You're better off spending the time trying to wash your cat.
> 
> Why? IMO its a waste for several reasons. 1) unless you can somehow stop the cause of the buildup, you haven't fixed anything, it will be gunked up again a week later. 2) as you observed there is no performance gain. It's a turbocharged motor, air will get rammed through regardless of a bit of gunk on the valves.
> 
> ...


 This is a prime example of talking out of your ass. 

I'm not for snake oil, but when your valve stems are 3x as thick and the seats won't seal anymore it certainly makes a difference. 

It's not a performance mod, it's preventative maintenance


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## Krieger (May 5, 2009)

blackvento36 said:


> This is a prime example of talking out of your ass.
> 
> I'm not for snake oil, but when your valve stems are 3x as thick and the seats won't seal anymore it certainly makes a difference.
> 
> It's not a performance mod, it's preventative maintenance


 :beer: 

also, 23 MPG???? holy **** man, i get better than that when i am wooping her ass daily. im sad when i go below 27...


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## xtravbx (May 21, 2005)

Krieger said:


> :beer:
> 
> also, 23 MPG???? holy **** man, i get better than that when i am wooping her ass daily. im sad when i go below 27...


 
Roof racks that aren't very aero KILL gas mileage. 

Too much for me to consider running one regularly.


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## pwzfl (Oct 2, 2007)

Hi,
I had the same problem, CEL went on so I went to my local VW dealer, where I was told that carbon build up causes misfire, and clean up would cost me $850 plus tax! 

Went to my VW mechanic who did cleaning for fraction of that price, yet he said the misfire is not caused by the carbon buildup but by moisture in the engine! He said that he turned off the CEL, yet he believes it'd be back on in a week or so. And he was right. Few days later the CEL was back on!

After I did some research, I found that ethanol which is in gasoline draws moisture from the air. Decided to give a try to non-ethanol gasoline (recreational 90 octanes) 

Few weeks later I noticed my MPG went up from 27 to 30MPG and check engine lights has been turned off ever since. My guess, FSI engines are designed for Europe, where gasoline does not have 10% of ethanol in it. Here, the carbon buildup, moisture in the engine, which causes misfire, will be always an issue for direct injection engines....


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## jlang002 (Oct 4, 2010)

pwzfl said:


> Hi,
> I had the same problem, CEL went on so I went to my local VW dealer, where I was told that carbon build up causes misfire, and clean up would cost me $850 plus tax!
> 
> Went to my VW mechanic who did cleaning for fraction of that price, yet he said the misfire is not caused by the carbon buildup but by moisture in the engine! He said that he turned off the CEL, yet he believes it'd be back on in a week or so. And he was right. Few days later the CEL was back on!
> ...


Most people won't have easy access to pure gas. I sure as hell don't and I'm in a metropolitan area near the water.


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## pwzfl (Oct 2, 2007)

jlang002 said:


> Most people won't have easy access to pure gas. I sure as hell don't and I'm in a metropolitan area near the water.


check this out: 

http://pure-gas.org


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## pwzfl (Oct 2, 2007)

some of those symptoms I already have had and my VW Passat is 75,000 miles old....

http://www.fuel-testers.com/list_e10_engine_damage.html

coincidence? I would be skeptical if I did not experience some of those problems already... and I have always been buying premium gasoline at BP!


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## Krieger (May 5, 2009)

if you want to draw water out of the fuel, throw some meth in the tank. ethanol attracts water, methanol binds with the water and allows it to be burned off safely.

but, i seriously doubt that 10% ethanol is causing your missfires... it usually would cause engine bogging and very poor performance if there was that much water.


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## pwzfl (Oct 2, 2007)

Krieger said:


> if you want to draw water out of the fuel, throw some meth in the tank. ethanol attracts water, methanol binds with the water and allows it to be burned off safely.
> 
> but, i seriously doubt that 10% ethanol is causing your missfires... it usually would cause engine bogging and very poor performance if there was that much water.


Maybe you're right, but since I have been using non-ethanol gas my CEL has been off and car performs like new so....


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## Bill6211789 (Dec 11, 2009)

pwzfl said:


> Maybe you're right, but since I have been using non-ethanol gas my CEL has been off and car performs like new so....


You must have horrible gas in your area then.... Myself and everyone i know that has a 2.0t fsi runs 93 oct with 10% ethanol and has no issues..... And same goes for most that have carbon build up it does cause misfires in your case it may have been somthing different but more often then not FSIs with higher mileage that are having misfires, is due to carbon build up 

Sent from my EVO 4G


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## ROH ECHT (Dec 9, 2010)

I use my own pressurized bottle to spray Mineral Spirits into my T/B every 10k miles. I never have misfires using 10% ethanol or eth-free gas and I'm currently averaging 28.8 mpg on 92 oct (ethanol free) for the last 1500 miles. I've never removed my intake and manually cleaned the valves.Seems like too much work when spraying seems to be doing the job for me. I'm at 82k miles right now.


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## bck6780 (Jul 16, 2010)

Regarding the thread posted at the very top..38ish mpg?!? Are you kidding me?

Does anyone else with a 2.0t see this economy? I average 26mpg combined (08 gti 6mt, revo stg1)


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## BCinco (Dec 17, 2006)

bck6780 said:


> Regarding the thread posted at the very top..38ish mpg?!? Are you kidding me?
> 
> Does anyone else with a 2.0t see this economy? I average 26mpg combined (08 gti 6mt, revo stg1)


You're right up the coast from me, kinda.

I average about the same as you. I have a 22 mile commute each way on I91, 10 miles round trip to the gym every morning on the Merritt, and some around town errands. I thought I'd be getting more...


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## xtravbx (May 21, 2005)

bck6780 said:


> Regarding the thread posted at the very top..38ish mpg?!? Are you kidding me?
> 
> Does anyone else with a 2.0t see this economy? I average 26mpg combined (08 gti 6mt, revo stg1)


I'm at about what you are. 08 MT. 

I drive pretty conservative but still have my fun. Just replaced my coil packs and fuel filter and have 46k miles. 

Sent from my Jelly Belly using Tapatalk 2


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## Krieger (May 5, 2009)

you must do a ton of city driving. i live in a smaller area but travel alot... i tend to be in the low 30's for a whole tank.


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## bostonaudi1 (May 14, 2006)

blackvento36 said:


> This is a prime example of talking out of your ass.
> 
> I'm not for snake oil, but when your valve stems are 3x as thick and the seats won't seal anymore it certainly makes a difference.
> 
> It's not a performance mod, it's preventative maintenance


Who's talking out of their ass? If the injector itself is dirty car will misfire for sure. Some buildup on the stem or oily residue on the port walls doesn't effect things nearly as much as some are apparently suggesting. Its a turbo, air is rammed through! Typically the only way the valve won't seat properly is if it burns, cracks or plain wears out and that doesn't happen in modern engines till past 150k. If you've ever taken one of these engines apart you'd quickly note just how much crap and oil gets pushed through the intake, a sparkly clean set of valves on these engines gets dirty again quickly. My 08 FSI consumes nearly a qt per 1000, I'd have to take the manifold off every week to keep it clean!

We all want our engines to run right, I'd suggest a regular quality chemical induction clean (B&G etc), or a good hard drive now and then is a better and less intrusive way to keep things under control than removing the manifold and risking getting a real misfire by getting dirt or lint into the fuel line or injector. It only takes a microscopic piece of debris to **** up an injector.


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## jlang002 (Oct 4, 2010)

pwzfl said:


> check this out:
> 
> http://pure-gas.org


That's what I was basing my statement on. All stations are on the eastern shore of Maryland, nowhere near where I am located.


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## Krieger (May 5, 2009)

sure, air goes through, but it does get obstructed and it can indeed lead to misfires and improper sealing of valves, hence people getting erratic idle, poor mileage, poor performance, etc etc. When I had mine cleaned a while back, they were freaking filthy... the motor felt ok to me before the cleaning... but when she was put back together... omg did it wake her up! think about it... instead of a smooth slipstream over the valves, your getting unaccounted for tumbling and restriction of air flow... you cant possibly tell me that won't be detrimental to your motor's performance...

pics of my valves at like 60k


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## xtravbx (May 21, 2005)

Krieger said:


> you must do a ton of city driving. i live in a smaller area but travel alot... i tend to be in the low 30's for a whole tank.



this. i drive for work, a lot of city driving, driving in crappy traffic on 95, etc.


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## gmikel (Nov 10, 2010)

*carbon*

i've got 102k on my 06' jetta 20t. cleaned the valves by hand a year ago and saw improved idle. gave it a good dose of seafoam friday and again got an improved idle. as for gas mileage, i live in a rural area and get 30mpg on bad tank and 32 on a good one. no change after cleaning valves. everyone's situation is a little different.


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## bck6780 (Jul 16, 2010)

Holy crap thats a lot of buildup, thanks for the pics! Just picked up some new plugs and fuel filter, but I think a good seafoam-ing wouldn't be a bad idea either....link to DIY?
:beer:


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## BCinco (Dec 17, 2006)

bck6780 said:


> Holy crap thats a lot of buildup, thanks for the pics! Just picked up some new plugs and fuel filter, but I think a good seafoam-ing wouldn't be a bad idea either....link to DIY?
> :beer:


http://www.youtube.com/watch?v=DmMvi7o6Ja4

But I'm in Meriden, so you should go the whole 9 and get a BG service /endshamelessplug


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## bck6780 (Jul 16, 2010)

Haha yeah I mean BG would probably be safer anyway, I believe its safe for cat. converters while Seafoam is debatable. Very easy DIY though.


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## mrbikle (Jul 2, 2005)

there is so much misinformation in here....


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## bck6780 (Jul 16, 2010)

mrbikle said:


> there is so much misinformation in here....



..OK, then please contribute! There's no point in expressing a negative opinion without giving a reason or evidence. We're all trying to learn here.


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## BCinco (Dec 17, 2006)

I think it is beneficial to clean out your valves. I can tell the car idles and pulls smoother. I'm a fan of technology, machinery etc. functioning as it was intended to. Anyway here's my before and after pictures of my experience.

http://forums.vwvortex.com/showthread.php?5749626-I-spent-my-4th-of-July-cleaning-my-valves


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## imcginnis (Apr 2, 2010)

All direct injection engines have this problem, and each manufacturer has different ways of cleaning them. The fact is that it will eventually cause a cold start misfire, and it will look like crap in there at 15000 miles. We have taken manifolds all sorts of customer cars just to look inside there and say wow that looks terrible. But it does not cause a misfire so the customer does not care.


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## xtravbx (May 21, 2005)

bck6780 said:


> ..OK, then please contribute! There's no point in expressing a negative opinion without giving a reason or evidence. We're all trying to learn here.


Seeing that this thread was revived from the dead - 

seafoam / cleaners will do nothing. So he was probably referring to people using something like that through the IAT or PCV port.


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## [email protected] (Aug 21, 2008)

I have done a couple of RS4s and customers were having tears of joy


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## xtravbx (May 21, 2005)

[email protected] said:


> I have done a couple of RS4s and customers were having tears of joy



Wish you were in FL.

I don't feel like having my car out of commission tearing apart the IM. Plus it's probably more work than I've ever attempted.


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## Bill6211789 (Dec 11, 2009)

xtravbx said:


> Wish you were in FL.
> 
> I don't feel like having my car out of commission tearing apart the IM. Plus it's probably more work than I've ever attempted.


First time sucks, but just think its practice for oulling the IM for when u go with a bigger turbo and need those larger injectors  

Sent from my EVO 4G


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## xtravbx (May 21, 2005)

Bill6211789 said:


> First time sucks, but just think its practice for oulling the IM for when u go with a bigger turbo and need those larger injectors
> 
> Sent from my EVO 4G



I should just do it.

I did the clutch on my Acura Integra back in the day. That involved dropping the transmission and was a lot of work.

I think I could manage it.


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## theronin (Aug 6, 2012)

xtravbx said:


> I should just do it.
> 
> I did the clutch on my Acura Integra back in the day. That involved dropping the transmission and was a lot of work.
> 
> I think I could manage it.


the first time is rough. requires alot of patience and liberal use of an extending magnet  but imo totally worth it. make sure to have a new mani gasket and 4 seal kits for those injectors.


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## CE (Jan 21, 2001)

*clean Valves yup*

after a clean up my mpg went up 4mpg, no more cold start check engine light. It matters, gets really gunked up, affects air flow and turbulence. A cure is supposed to be coming


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## Tutti57 (Jun 20, 2011)

What is the cure that you speak of?


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## bck6780 (Jul 16, 2010)

A cure for this would be awesome.

In their patent for their DI engine, VW acknowledges the problem and provides some pretty hardcore fixes, like coated valves and walls, but I think the most we can do is essentially re-route exhaust gas blow-by somewhere else so it doesn't stick.

I'm really interested to get my hands on the mk7..Apparently they have a dual-stage DI system, and the second stage of the system is actually designed to "rinse" the gunk off the valves (as they also elude to in their patent!)


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## TokyoVW3.2FSI (Sep 28, 2013)

*Just got my engine down*

I ve had different problem though. nonetheless I saw the same problem on my valves,I will have to clean, I am in Tokyo dont know if gas stations uses ethanol or not.

Since I ve the engine down, I will revise here and there.


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## ROH ECHT (Dec 9, 2010)

*I re-did my diy vid using a new sprayer*...






*On guy bore-scoped his, before and after, after doing this at 120k miles for me and having never cleaned them before*...

*Before*


*After*


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## dmorrow (Jun 9, 2000)

Good video and information. Did you consider a stronger solvent? How much do you think you put in the engine? After adding it, seems like it would be worth letting it sit for a couple of hours before running the car. 

I can't tell much from your pictures, estimate on how much cleaner?

Based on the amount of time and money spent doesn't seem like a bad plan, difficult to say how well it works.


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## cameron2pt5 (Oct 19, 2006)

*Low RPM driveability?*

I have an 2006 BPY w/MT and 100,000kms. So far no CEL and runs good, but at low RPM 1,100-1,300 the car stumbles and power delivery it jerky. This is most noticeable when I am creeping along in bumper to bumper traffic. I would think consistent filling of air/fuel into the cylinders at this RPM would be problematic if your valves are dirty.

Has anyone whose cleaned their valves noticed an improvement in stop and go traffic and engine smoothness at very low RPM?


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## Millennium Falcon (Jan 29, 2004)

Yes


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## ROH ECHT (Dec 9, 2010)

dmorrow said:


> Good video and information. Did you consider a stronger solvent? How much do you think you put in the engine? After adding it, seems like it would be worth letting it sit for a couple of hours before running the car.
> 
> I can't tell much from your pictures, estimate on how much cleaner?
> 
> Based on the amount of time and money spent doesn't seem like a bad plan, difficult to say how well it works.


Thank you...The second pic isn't as close as you'd like, but if you look closely you can see the valve stem that was completely caked before is completely free of build-up afterward. You can even make out the brass valve guide is free of build-up too. I use M.S. because it dries slowly but does burn out. It is also what is in Fleming's BG44K...so I use their cleaning method per their own diy instructional vid. Only I use more...Their product averages approx. 30% M.S. so I guess I use 3 times that much. I don't think allowing it to sit would be possible as it has mostly blown through when running...but you could easily spray some when not running to soak in. But it does a thorough enough job done as is and doing it every other oil change would result in cleaner intake ports than that in the pics from the guy only doing this once at 120k miles I hope ;p


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## ROH ECHT (Dec 9, 2010)

cameron2pt5 said:


> I have an 2006 BPY w/MT and 100,000kms. So far no CEL and runs good, but at low RPM 1,100-1,300 the car stumbles and power delivery it jerky. This is most noticeable when I am creeping along in bumper to bumper traffic. I would think consistent filling of air/fuel into the cylinders at this RPM would be problematic if your valves are dirty.
> 
> Has anyone whose cleaned their valves noticed an improvement in stop and go traffic and engine smoothness at very low RPM?


Mine always runs better in the lower rpms when cleaned. I notice it quite clearly...very little throttle pressure invokes the motor to respond immediately and idle is tight and smooth.


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## theGLIguy (Dec 2, 2011)

Bill6211789 said:


> how come after cleaning my valves do i see better MPG's? best i could see before valve cleaning was 27.xx MPG's now I'm in the 30s


my car has 100k and my valves have never been cleaned. They have bad carbon build up too. I'm averaging 32mpg on my way to and home from work. I would like to and it might work.... for a while! if your not running a catch can, your best bet is to just seafoam them every so often but that's it.


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## bbanaszewski (May 11, 2007)

Bill6211789 said:


> You must have horrible gas in your area then.... Myself and everyone i know that has a 2.0t fsi runs 93 oct with 10% ethanol and has no issues..... And same goes for most that have carbon build up it does cause misfires in your case it may have been somthing different but more often then not FSIs with higher mileage that are having misfires, is due to carbon build up
> 
> Sent from my EVO 4G


I beg to differ on the 93 octane. I have NEVER been able to get my 2.0 to run 93. The mileage tanks. It was HELL buying gas in Japan with it
I might have gotten 18 mpg while there. Any thoughts? Someone said o2 sensor but I haven't had time to play with it since I got back. Silver (89) is the best I can run but I get 31 on the highway
Not bad for 110k on an 06 GLI


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## ROH ECHT (Dec 9, 2010)

I always notice better performance, smoother running, less smoke under boost, improved throttle response, and better mileage. I inject 8oz each of spirits, naphtha, and fuel.

Finally got my own, cheap, bore-scope. Three days ago:

Before ↓:



After ↓:


*
Finally VW addresses the problem by adding 4 injectors, in addition to the 4 cylinder injectors, in the intake mani of the Mk7 to inject fuel during idle and low rpm's...and switching to direct injection for performance. Now a fuel additive along with low rev fuel passing by the valves the excessive intake valve build-up is remedied.*


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## thegave (Dec 22, 2008)

Has anyone tried doing the old water up a vacuum line trick? Would that work for cleaning the valves etc. old carb cars used to have it done as regular maintenance to "de-coke" the head


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## aznsap (Aug 7, 2010)

ROH ECHT said:


> Mine always runs better in the lower rpms when cleaned. I notice it quite clearly...very little throttle pressure invokes the motor to respond immediately and idle is tight and smooth.


i have to agree w/ ROH ECHT here. i just cleaned my valves, some pics on in the thread i started:
http://forums.vwvortex.com/showthread.php?7015690-Cam-follower-intake-valve-cleaning-thermostat-semi-DIY

while no objective measures of difference before and after, there's a noticeable improvement in low rpm response and smoother idle.


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