Audi FSI Engine Carbon Build-up Megathread

[saw76]

I have the BG machine and a BG rep that supply's my shop with product and can say that regularly using this with help with carbon build up .
It cleans the hard cooked stuff to an extent but will not remove the heavy baked on crap in there completely . I recommend to all my direct injection customers a regular cleaning using this tool. It's best to remove the intake and related parts , manual clean everything and then start a induction service schedule .

[East]

Bought my S5 @ ~27600 miles and idled ROUGH from the start. Rough idle seemed to intermittently clear after "spirited driving" (beating on it). Misfire CELs started around 38k but really had always idled slightly rough.

Brought the car to the dealer twice under warranty, first time, they reflashed the ECU which temporarily softened the idle and cold acceleration. Misfire CELs recurred within 2 weeks.

Second trip around 9/8, dealer held the car overnight and confirmed cold start misfiring and immediately performed a "full carbon cleaning." Got the car back on 9/12 and it felt sprightly as never before. This morning, CEL came back on (with no real symptoms), and I'll be returning to the dealer for a follow up.

Wondering if anyone had a "full carbon cleaning" and still experienced CELs shortly thereafter.

[mixofia]

2007 Audi S6
Rockville, Maryland
51k as of May 2011
Mobile One 0W 40
Every 5k miles
Always 93 Octane Exxon or Shell
20 miles to and from court most days


I am the second owner, having acquired the car in February 2009 with 14k on the clock. No mods to the car...yet. It's my daily driver. The car started throwing CEL codes in the Fall 2010 when I made a very hard acceleration. The light would flash repeatedly and then stay solid. The first time this happened in November 2010, Audi replaced my coilpacks and air intake flap motor under warranty and the applicable TSB. That cured the CEL for about a week. Another hard acceleration and the CEL was back on. I then noticed that the car bogged down very noticably at 4,000 rpm. It would struggle to accelerate and hard a hard time increasing rpm's. Again, the CEL would flash. I went to the delear in April and they reset the CEL and updated certain software (I do not have the exact software since they still have my car and do not have final paperwork). I was told by the head mechanic there that my car was misfiring very badly on cold starts. The software update seemed to cure the misfires on cold start...for about three days. After the software update, I drove the car three days later and threw an engine code. Back to the dealer with VAG-COM report in hand showing misfires in cylinders 5, 6, & 10. They suggested the 55k service. I suggested that they contact AoA about carbon issues. They got the 55k service from me and I got a full carbon cleaning from them. Picking up the car in 30 minutes. Should be interesting with new plugs, new oil, new filters, and no carbon deposits.

Same car with 85K on the odo, similar situation. I was getting an occasional flashing CEL when I crossed 4000 RPM - misfire cyl 8. Changing the coilpack did not fix. Audi tech said, "maybe a clogged fuel injector?" So I just added a can of BG-44K with fingers crossed. Drove 1/2 a tank so far with frequent runs up to 5000+ RPM. I noticed it ran rough at 2K for awhile, but now it's pretty smooth. However, I still get the occasional flashing CEL when I cross 4000 RPM. Also checked the records and the car's dealer service record shows "Fuel Injection system flushed" about 1 year/5000 miles ago.

Any other suggestions before I resort to a full carbon cleaning? Should I drive out the tank/BG-44K before I draw any conclusions? Take it up to redline?
What is the long term outlook if I ignore this for awhile - the car drives pretty smooth as a daily driver.

The car has gone "expat" to BG, so while I'm sure I can find a dealer to get software updates/service, but it won't be super easy with my limited language skills.

[monica12]

Hello All,

2010 A4 2.0T Premium
CPO: brought at 19k miles
Now: 41k miles
issues: Stalling at acceleration, drop in fuel mileage

I have read most of these threads for a year now and have come to the conclusion that I have carbon buildup. A service Manager mentioned it, but did not grant my request for it under warranty. When I went back, he said "that may not be the issue" So ridiculous. I have been to the dealer 18 times for a hard stalling and lagging upon acceleration. They now say I have no issue with the car. Really after 18 visits.

Some may not know about the Magnus and Moss warranty act, but anything over 1,000 qualifies. You can sue them for keep having to go to dealer. I worked with an out of state firm called Khron and Moss. Look into if you've been screwed like me...They will get you money. You may can get $10,000 I'm contemplating even accepting the money because I'm still not sure what is wrong. I'm guessing carbon from reading here. Also my miles to empty went from 500 to 350. Crazy right!!! Now Audi told me not to come back to dealer. What is sad is that I have only 41k miles. This started at 20k miles. Get this I'm still in new car warranty, have 1 yr left. These cars are nice to ride in, 2008-2010 models are prone to these issues. Guess they want me to wait until the warranty is up!!! wont happen. Keep all repair orders and call 1888 Audi number if your dealer sucks like mine. If they don't help, as per usual, LAWYER!!!!!!!!!!!!!!!!!!!!

[monica12]

Forgot to mention, car had 1 owner. I have never had any fault codes ever.

Spark plugs changed 2x's and Transmission readaptation /flush at 35k

I only use Shell 93 oct gas. And change oil every 5k miles.

I also change oil, pollen, air and fuel filters every 5k miles too!

Questions:
Would an engine flush help w/carbon?
Does carbon ultimately damage engine?
A local luxury repairman mentioned perhaps improper air/ fuel mixture? any deets on that?

[saw76]

Forgot to mention, car had 1 owner. I have never had any fault codes ever.

Spark plugs changed 2x's and Transmission readaptation /flush at 35k

I only use Shell 93 oct gas. And change oil every 5k miles.

I also change oil, pollen, air and fuel filters every 5k miles too!

Questions:
Would an engine flush help w/carbon?
Does carbon ultimately damage engine?
A local luxury repairman mentioned perhaps improper air/ fuel mixture? any deets on that?

Monica ,
You should try to find a recommended Audi / European speciality shop that's not a dealer , bring all your paperwork , explain all this to them and see if they can help .
They might be able to remove some stuff to gain access and then digital bore ship it to see inside , you will have to pay for it but if they find grounds to go further maybe after its cleaned manually you can get reimbursed or something , or drive to a better dealer :-(
It kinda sounds like it could be carbon .

[TheBlueMartin]

I just dove into my 3.2 with 192,000 miles on the ODO. Slightly longer start times in the morning than I'd expect, fuel mileage has been getting worse over the past year, and it blows a little black smoke out the exhaust when 4000RPM and above at WOT.
The valve covers are pouring out oil as well as flooding the spark plug bores, so while i have it apart to replace those I decided to do the valve cleaning (assuming it would need it knowing how bad the issue has been for Audi).
Yeah, its bad:





So far carb/choke cleaner sprayed on the closed valves has broken up all the hard carbon, but getting the massive amount of carbon out is an ongoing task.

[TheBlueMartin]

And after:

[jayulzvern]

^ which method did you use? I would like to do this to my 3.2 too. I am getting black smoke on WOT also.

[TheBlueMartin]

I used a set of Matco picks and a small wire brush, scraping out as much carbon as a I could and then vacuuming out the dry dust/pieces. Then I used throttle clean to spray down what was left, and forced small pieces of Scott blue shop towels around the back side of the valve to push what was left around. Finally, I used brake clean with the blue towels to get any smudges.
This is a VERY precise and time intensive job. I highly recommend only people that are very confident in their mechanical skills do this. Not only can you ruin your engine if you do something wrong, I would guess I'll have 10 hours in it when I'm all said and done.

[mixofia]

Same car with 85K on the odo, similar situation. I was getting an occasional flashing CEL when I crossed 4000 RPM - P0308, misfire cyl 8. Changing the coilpack did not fix. Audi tech said, "maybe a clogged fuel injector?" So I just added a can of BG-44K with fingers crossed. Drove 1/2 a tank so far with frequent runs up to 5000+ RPM. I noticed it ran rough at 2K for awhile, but now it's pretty smooth. However, I still get the occasional flashing CEL when I cross 4000 RPM. Also checked the records and the car's dealer service record shows "Fuel Injection system flushed" about 1 year/5000 miles ago.

Quick update: I found my personal "audi mechanic" here in Sofia, BG who has been helping me track down this issue in my 5.2L v10. Here is what we have done:

1. re-seal intake cover gaskets (found oil in wells of 4 spark plugs)
2. swap cyl 7 & 8 spark plugs
3. 200ml of G001770A2 (G17) fuel additive to 60ltrs of fuel

The resealing of the intake cover gaskets was a big fix - it cleaned up rough idle at cold starts immediately (but that was a more recent problem). However, by itself it did not eliminate the P0308s.

Sometime after that, I went for the fuel additive, and I have been surprised at the possible results. It was not immediate, it took about 3 tanks/1000 miles AFTER the fuel additive, but I am no longer getting CELs at WOT. A VAG-COM scan still shows intermittent P0300 misfires, but it never lights up. And it seems to be driving fine.

My guy suggested I do another cycle of the G17 + 1000 miles, then we'll pull the intake manifolds and have a look for carbon deposits. Apparently with the V-10, it's a big effort.

BTW: when I took it to the Dealer for this problem, they did a test drive and inspection - where they discovered oil in the plugs. Then they suggested I replace both intake covers and the entire intake manifold, about $2500 in parts. I haven't had to do any of that yet...

[TheBlueMartin]

So there is a new oil vapor separator for the older 3.2's that should help reduce the carbon issues we have. Wish I would have seen this before I got mine all back together:

http://www.hengst.de/conpresso/_data...Technology.pdf

http://www.ecstuning.com/Audi-C6_A6-...Emissions/PCV/

The visual difference is the plastic housing of the new part compared to the aluminum housing of the old one.



Edit: After searching some more, I've seen this new part in the background of 3.2's getting carbon cleaning, so it must not be a fix-all like Hengst makes it out to be.

[Mooberz]

sitting at 130k miles.. car was running good till it hit 120k.. then started getting the car shaking at startup esp during cold would be ok after warmup.. did the seafom.. helped for like a month then back to same thing.. a 2nd seafom no help. Took it to the shop.. that does audi Mercedes etc.. with a check engine light.. got it back a week later with a 130k maintence package blah blah new plugs etc etc... got it back with a chunk of the air intake gone.. the plasic piece.. and now I have an EPC light. on.. They say its kuz my engine is diry and the flaps are not opening they are stuck. and will cost around 3k to fix because will need new intake manifold and motors for the flaps? (I'm pretty sure they broke it ... I mean come on check engine only light to check engine and EPC? ) he said it will run fine but cant got WOT because flaps wont open and it will bog down. so I'm like ok let me go on vacation then come back and ill schedule a fix... while on vacation decided to take to dealer to see what they say.

software upgrade/flash on car is $72 replaced a cam sensor coolant leak + take off the manifold and look inside at flaps etc.. was total around 2100, they took out the manifold.. said there was pieces of the flaps flopping around and carbon was terrible. new manifold 1900 and cleaning manifold 800 to clean all the carbon then 1900 for the intake manifold. 4800 total... said car will run like new... we shall see.


here are the preliminary pix of the manifold at 130k miles.

[jonmartinez223]

Vehicle Make/Model : 2009 Audi S5
Location: What state/country the car was driven primarily : Denver, Colorado
Mileage/Date in which CB was discovered : 67,0000
Oil used : Castrol Synthetic
Oil Change Interval : 5k Miles
Fuel Used : Sinclair / Costco / Conoco 93 Premium
How short/long are your trips on average : 5 Miles - 25 Miles

Noticed my car running poorly. No Engine codes or anything like that. Just purchased it at 60K miles and the previous owner has had it since 10k miles. He said he never really stepped on it. After noticing my car running a little sluggish, my brother and I decided to open it up and take a look at the Intake Valves. No surprise that they were in rough shape, and full of carbon. We followed a few DIY to open it up. At the current moment, we are a bit stuck because 5 Valves are closed but 3 stayed open. It is an Automatic Audi S5 and the Parking "hand break" was enabled prior to opening the car up. Does anyone have any ideas on how we can get the last 3 valves to fully close so we can continue cleaning them? Any help will be greatly appreciated.

[jschrauwen]

I used a set of Matco picks and a small wire brush, scraping out as much carbon as a I could and then vacuuming out the dry dust/pieces. Then I used throttle clean to spray down what was left, and forced small pieces of Scott blue shop towels around the back side of the valve to push what was left around. Finally, I used brake clean with the blue towels to get any smudges.
This is a VERY precise and time intensive job. I highly recommend only people that are very confident in their mechanical skills do this. Not only can you ruin your engine if you do something wrong, I would guess I'll have 10 hours in it when I'm all said and done.

What was your end results for your 3.2? Was there a noticeable improvement? Would you recommend the walnut shell blasting process for the 3.2?

[skylinrcr01]

I did my valves on my 3.2 a6 a couple months ago and it solved the lurch that I had when accelerating from a dead stop, also smoothed idle out a bit. Did not solve my misfire in cyl 3 though, I think that may be an injector, since I've done coils and plugs already.

[illegitimus]

It is an Automatic Audi S5 and the Parking "hand break" was enabled prior to opening the car up. Does anyone have any ideas on how we can get the last 3 valves to fully close so we can continue cleaning them? Any help will be greatly appreciated.

Might be too late and you had figured out how to do this but on my A4 2.0T, the 1st and 3rd cylinder valves were also open when I took the manifold off. What I did was, put car in neutral, take the timing belt cover off to expose the camshaft bold. Put a socket wrench to it and turn hard clockwise! It'll be a little hard but the valves should move significantly, do not be afraid to turn it with force. Have your buddy watch for the valves to move up and down as you turn the bold of the camshaft and watch for complete cycle and figure out when to stop to ensure your 3rd cyl valves are completely closed... I hope this helps you or whoever else is manning up to accomplishing this.

[jschrauwen]

I've procrastinated long enough. I'm scheduled for a walnut shell carbon cleaning tomorrow morning.
I was referred to this place by a 08 TT 3.2 owner. http://techmax.ca/

I have a couple of "while-I'm-in-there" type of questions.
1. While the intake manifold is off, should I look at having the PCV's replaced? I ask this because they are the leading contributor to depositing an oil film onto the intake valves that eventually gets baked and hardened onto.
2. Someone also suggested I should look at replacing some of the vacuum lines under the manifold as well?

[TheBlueMartin]

What was your end results for your 3.2? Was there a noticeable improvement? Would you recommend the walnut shell blasting process for the 3.2?

I don't have a good enough containment system to trust using walnut shell. If someone came up with a unit that just bolted onto the port and blew the media around without letting it escape, I would go that route. Otherwise you're just going to make a huge mess all over the engine bay.
I did not feel an increase in power, but the start times and throttle response was very much improved.

[jschrauwen]

Well I'm completely floored. The tech calls me into the shop from the waiting room. That usually means bad news but not this time. The tech shows me the intake valve train and he says their perfectly clean. Like almost brand new. I wasn't expecting this at all.
Since everything was removed, they just did a quick tertiary cleaning by hand with cleaners.
These pics were before the cleaning.







That check up was done last month at ~ 98k kms. I've only had the car for a year. Previous owner of 4 years was an elderly lady in Ottawa who only drove it in the summer months and stored the other 6 months while she was in Florida during the cold months. (Granny driving at it's best, lol) My main concern was that it may have seen a lot of very short and very slow speed use during those 4 years which is a prime catalyst for carbon build-up.
My driving however is 100% opposite. For the last year it only gets driven a few times a week. When it does get used, it's usually for drives of over 2 hours duration at highway speeds. I live in the country so even shorter commutes are at 80kph + on the rural roads.
I've been using PetroCan 94 octane this past year as it's been my gas of preference for the last 25+ years. Atilla at www.techmax.ca enlightened me to the fact that that gas has over 30% ethanol in it. His shop actually has testing apparatus to determine this. His advice was to use another gas without any ethanol for the sake of the injectors. The injectors and combustion burn process is better in a naturally aspirated Audi (like my 3.2) without the ethanol content unless the car has been specifically tuned for it. I have now switched to Shell 91 octane as it apparently has zero ethanol. I even downloaded a free App to my phone so that I can find non ethanol 91 octane gas stations wherever I go.
I believe oil type has a small part to play in the carbon build up process. IE: Not using one of the Audi prescribed/recognised oil types can possibly contribute to greater PCV blow-by which of course coats the inside of the intake manifold resulting in build-up on the valves. I've been using Motul oil since I got the car and change it roughly every 6k kms.

[Jake@JHM]

If anyone is looking to do a carbon cleaning, we got you covered!



Click HERE: https://jhmotorsports.com/shop/catal...+clean&x=0&y=0

[zazzmaster]

I noticed that the A8 is not listed at the beginning of this thread. Wondering why. Has this problem been reported with the 4.2, 3.0T, and 4.0T engines used in the A8?

[Jake@JHM]

I noticed that the A8 is not listed at the beginning of this thread. Wondering why. Has this problem been reported with the 4.2, 3.0T, and 4.0T engines used in the A8?

all direct injection engines (FSI/TFSI) engines

[Sodium]

Walnut grit blasting makes a big 'ol mess and it's a challenge to keep it out of the injector ports but really is the only thing that does the job properly, IMO.

I use medium grit blast material and it takes a little kajiggering around to get everything off but it's a once in a long while maintenance cycle and once you've done it it's pretty simple. I've found it helps to have a helper on hand to operate a shop vac to gather grit as it's used and that stuff gets everywhere but it can be done single handedly. Sucking up all the left over blasting grit once the cleaning is done is as much work as actually cleaning the valves.

[jschrauwen]

I just heard recently on the A5 Facebook page that blasting with a derivative of baking soda is supposed to be even more effective then walnut shells. First I heard of that, but who knows.

[b4rs290]

Just did mine this weekend I found it helps to scrape and vacuum first then flood with your chem cleaner and I used a wire brush to break everything up.to close open valves I cranked the motor with the key for a quick sec and got the valves to close.

[TheBlueMartin]

We see carbon related issues on a daily basis now, some drivers have tried all kinds of additives to help but nothing seem to work but manual cleaning.
we been using 10w-60 on a few FSI engine for a while now with very positive results, lower oil consumption by a lot and so far hardly any carbon in the intake runners and intake valves.

Now that there is a few years on this quote, can you report back that 10w-60 has had a long term effect on lowering carbon buildup? I've thought about running this in the summer months

FYI, there are no 10w-60 oils that meet VW.502 standards, so don't void your warranty (not that many of us have warranties to worry about)

https://www.audiusa.com/content/dam/...e-Bulletin.pdf

[jschrauwen]

Now that there is a few years on this quote, can you report back that 10w-60 has had a long term effect on lowering carbon buildup? I've thought about running this in the summer months

FYI, there are no 10w-60 oils that meet VW.502 standards, so don't void your warranty (not that many of us have warranties to worry about)

https://www.audiusa.com/content/dam/...e-Bulletin.pdf

I too would like to hear about the long term effect of using a higher viscosity oil.
I've always liked the performance of the Motul 300V oils.
https://www.motul.com/us/en-US/produ...ition-15w50--2
https://www.motul.com/us/en-US/produ...-mans-20w60--2

[NYSpeedRacer]

2009 Audi R8
24.5k Miles
Twin Turbo for 6k-ish




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[jschrauwen]

Yikes!!!! Must have seen only city driving to get that bad.
Not enough periodic sustained high speed/rpm driving sessions.

2009 Audi R8
24.5k Miles
Twin Turbo for 6k-ish

[jschrauwen]

2009 Audi R8
24.5k Miles
Twin Turbo for 6k-ish

You're going to cry when you find out how much this R8 carbon cleaning cost.
https://www.youtube.com/watch?v=2yjMfC2m_s8

[NYSpeedRacer]

You're going to cry when you find out how much this R8 carbon cleaning cost.
https://www.youtube.com/watch?v=2yjMfC2m_s8

Wasn't that bad, about $2300 including new injectors, coil packs, spark plugs and an oil change


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[NYSpeedRacer]

Yikes!!!! Must have seen only city driving to get that bad.
Not enough periodic sustained high speed/rpm driving sessions.

Yeah, lately it has been. It was primarily used in Austin/NYC....could also be the twin Turbo? But that shouldn't have too much to do with it..right?


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[Fourplay]

Yikes!!!! Must have seen only city driving to get that bad.
Not enough periodic sustained high speed/rpm driving sessions.

That has literally nothing to do with carbon build-up. High RPM doesn't change the fact that there is no fuel washing over the valves and it also doesn't change the fact the the oil gets badly diluted with fuel (and therefore more volatile).

My recent RS4 carbon cleaning (third pic is partially completed cleaning - my phone died and I lost everything that hadn't been backed up to iCloud):







Would guess I'm making 40+ whp more. There is a significant difference in smoothness, power delivery, and top end power.

[jschrauwen]

That has literally nothing to do with carbon build-up. High RPM doesn't change the fact that there is no fuel washing over the valves and it also doesn't change the fact the the oil gets badly diluted with fuel (and therefore more volatile).

I'm afraid I have to disagree with you ... partially.
I refer you to post #140. You'll see pics of my valves at 98k kms that have never seen any cleaning. Why is it that mine "appear" to be in a much better state/condition then others with similar or lesser mileage? Is it possibly because I change my oil much more frequent then others (every 6k kms to 7k kms = every 4k miles to 4.5k miles)? Or perhaps that it always sees top tier oil - Motul and a Mann filter? That I use a K&N filter that gets cleaned/oiled twice a year? Or perhaps because I always use top tier fuel? Or maybe because in the last 2 years it sees 80% highway and 20% city? Perhaps because I give it an "Italian Tune-up" at least twice every time I use the car?
It's common knowledge for over 40 years that city type driving is a major contributor to carbon build-up in the combustion / exhaust portions of the car due mainly because of the lack of sufficient heat to prevent such build-up. Sustained highway driving is one way to counter that effect. Those generally accepted aspects can also be a player, albeit small, but a player nonetheless in an FSI type of engine. The lack of cylinder heat being transferred to the intake valves can theoretically contribute to the oily filmed intake air stream being deposited and and stuck to the backside of the valves. Had they seen more regular heat cycles (from highway driving), those deposits stand a greater chance at being burned off rather then gradually building up.
I firmly believe there may be a direct correlation between the type of use (city vs highway) and frequency of oil changes (short intervals vs those applying long life oil change practices) combined, create an atmosphere conducive to the rate at which carbon build-up occurs. It is not the end all to be all, nor the final solution by any means. But I believe it is one way we can stave off the effects of carbon build-up to reduce the frequency at which a real carbon cleaning is required.

I believe this guy basically nails it in those aspects.
https://www.youtube.com/watch?v=RnhUJsZXzmg

[Fourplay]

I'm afraid I have to disagree with you ... partially.
I refer you to post #140. You'll see pics of my valves at 98k kms that have never seen any cleaning. Why is it that mine "appear" to be in a much better state/condition then others with similar or lesser mileage? Is it possibly because I change my oil much more frequent then others (every 6k kms to 7k kms = every 4k miles to 4.5k miles)? Or perhaps that it always sees top tier oil - Motul and a Mann filter? That I use a K&N filter that gets cleaned/oiled twice a year? Or perhaps because I always use top tier fuel? Or maybe because in the last 2 years it sees 80% highway and 20% city? Perhaps because I give it an "Italian Tune-up" at least twice every time I use the car?

Everyone likes to think their car is special, but it's unlikely that yours is the only asymptomatic FSI car out there.

The fact of the matter is that there are hundreds of thousands of VAG FSI cars built since 2005, all of which suffer from this issue. VW's own patent for direction injection specifically states that preventing carbon buildup is impossible while also meeting emissions standards.

Oil filter type, intake air filter type, fuel type, and high revving driving have zero to do with carbon deposits. Frequent oil changes may help slightly because the oil in FSI engines suffers badly from fuel dilution, which can cause increased oil volatility.

Carbon deposits in early FSI motors are caused by PCV blow-by (the cyclonic separator isn't ever completely efficient) and the internal EGR system (FSI engines have a large amount of valve overlap to perform EGR functions, allowing combustion byproducts back into the intake tract).

There are hundreds of FSI owners on forums doing the exact same thing that you do (change oil every 5k miles or less, use only top tier fuel, rev the snot out of the cars, etc) who still have severe buildup (including me). It's much more likely that your car was cleaned before you bought it than it being some sort of never-before-seen unicorn with no buildup.

[lexcruiser]

Whats the recommended carbon cleaning interval for our engines (B8.5 S4 3.0T)?

[NYSpeedRacer]

Whats the recommended carbon cleaning interval for our engines (B8.5 S4 3.0T)?

It depends, did you lease it or buy it. If it's a lease I wouldn't worry about it, if you purchased it, I would do it at 30,000 miles.

[MSq5]

Just an observation as a new '17 3.0T Q5 owner: I come from a background of heavily modified Mazdaspeed 2.3L turbo engines. They are direct injection forced induction engines with the same or worse tendency to build up heavy carbon deposits on the back side of all of the intake valves. My 'Speed 3 is an '08 model, now 9 years old. I am the original purchaser and at about 140,000 miles. I've had to remove the intake manifold and clean those valves quite a few times, I think four in total and it's due again.

On our forums and user groups there has evolved two solutions, both of which I see reported above: crushed walnut blasting, or use of strong solvents and scrubbing with brushes. I am a proponent of the solvent soak and brushing technique. We discovered the same product that is mentioned above: Chemtool B12. It works very well. You can get most of the valves on the first application (all that are closed) and then rotate the crank to close the others. I use gasoline into the port to verify that it is closed. If it hold the fuel, it is ready to receive the solvent. If not, raw fuel will do no harm.

I simply let the solvent soak, scrub with the brushes (shotgun cleaning kit) use cotton cloth to soak up the solvent and carbon deposits and then blow the port out with compressed air. On a four cylinder the entire cleaning process actually takes only a couple hours. The time consuming part is all the steps to get the intake manifold out of the way and then put it back.

This is an issue that is common to all direct injection engines, to my knowledge. No real need to get our panties in a wad over it. It's a price we pay for the benefits of direct injection, which are many. The MZR Mazda engine may be more prone to this because the EGR valve dumps all of the unburned gasses back into the intake. Eliminating the EGR valve (which also requires a tuning modification to the ECU mapping to prevent the diagnostic code, can help slow down the progression of buildup.

I hope this report from a long-time user of direct injection forced induction engine from another platform might help shed some sight on the problem and on the solutions. I'm not sure we should expect this not to happen, quite frankly.

[jschrauwen]

Everyone likes to think their car is special, but it's unlikely that yours is the only asymptomatic FSI car out there.
That's not what I'm trying to say. If you look at the pics from my post (post #140) that were taken last year at approximately 100k kms, it clearly shows that the valves had not reached a state in which an aggressive carbon cleaning was warranted. At least that was the assessment of the shop. Surely in this age of over-selling tech services, they could have tried to substantiate a carbon cleaning, but they didn't.

The fact of the matter is that there are hundreds of thousands of VAG FSI cars built since 2005, all of which suffer from this issue. VW's own patent for direction injection specifically states that preventing carbon buildup is impossible while also meeting emissions standards.
Understandable.

Oil filter type, intake air filter type, fuel type, and high revving driving have zero to do with carbon deposits.
I guess we differ in our perspective on this.

Frequent oil changes may help slightly because the oil in FSI engines suffers badly from fuel dilution, which can cause increased oil volatility.
How is carbon build-up related to oil dilution by fuel? What is the connection here? Better yet, exactly how is the oil getting diluted by fuel in the first place? I would assume this can only be achieved in an FSI engine through either faulty injectors and/or failing piston rings?

Carbon deposits in early FSI motors are caused by PCV blow-by (the cyclonic separator isn't ever completely efficient) and the internal EGR system (FSI engines have a large amount of valve overlap to perform EGR functions, allowing combustion byproducts back into the intake tract).

There are hundreds of FSI owners on forums doing the exact same thing that you do (change oil every 5k miles or less, use only top tier fuel, rev the snot out of the cars, etc) who still have severe buildup (including me). It's much more likely that your car was cleaned before you bought it than it being some sort of never-before-seen unicorn with no buildup. My car was never carbon cleaned by the previous owner(s).

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