Carbon Build up and Cold Start Misfires on 2.0T TSI

May 27, 2015
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Carbon build up on the intake valves of your VW or Audi 2.0T TSI engine is inevitable.  Generally when it happens it will start with misfire codes sporadically when the car is cold(or has been sitting for a while).  These are often called cold start misfires and will likely get slowly worse over time.  You might also experience a decrease on your fuel mileage.  Both of these symptoms could be due to carbon build up on the intake valve, causing a blockage in the airflow inside your engine.

time to clean the carbon tsi

 

 

It is important to note we have never heard or seen a solution other than manual cleaning to remove this carbon.  Once the carbon has built up to the point where you are having an issue any chemical, service or the like will not work.  This is because once you are experiencing problems like cold start misfires, the carbon has built up so much even the most aggressive chemicals couldn’t take off that amount of carbon.  We do believe it is possible to regularly use a chemical like Sea Foam or another product every 10K to help prevent the carbon build up in the first place.  It might be worth it to look as the cost/benefit of doing the regular services versus having the valves cleaned every 60-70k miles.

 

The only way to get rid of this carbon build up is to remove intake manifold and clean the valves. To get the valves clean you will need to use chemicals, wire brushes and picks or a media blaster of some kind (like sandblasting).  This would generally need to be done ever 60k miles.  Take a look at the video below to find out why this happens.

 

Preventative Measures

  • Catch Can
  • Sea Foam or other chemical manifold services
  • Water Methanol Injection (Performance oriented)

 

Cleaning Solutions (Once you have carbon built up)

  • Manual Cleaning with Picks and Scraping (Intake Manifold off)
  • Media Blasting (Soda, Walnut and Others  (Intake Manifold off)

 

 

Why Carbon Builds up on the Intake Valves of your Volkswagen or Audi 2.0T TSI

 

 

Looking to Clean your Own Valves?

Below we have a DIY we did with The Humble Mechanic where we go over replacing the intake manifold on the TSI engine.  While this is not a DIY on cleaning the valves it will show you how to get to them and you can take it the rest of the way to remove the carbon.  Please note that when cleaning the valves its important to rotate the engine so the valves on the cylinder you are working on are closed.  This will ensure that no carbon deposits fall into the engine and potentially cause damage.

 

How to Remove the Intake Manifold on a 2.0t TSI

Paul Barrett

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53 Comments

on Carbon Build up and Cold Start Misfires on 2.0T TSI.
  1. Dave B
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    I just tackled the carbon cleaning on my B6 Passat and MkVI GTI. The Passat is un-modified, has had the PCV system replaced under the TSB, and is driven mostly by my wife. She recently flipped over 120k miles on the car and began getting a misfire code when the engine was under load. I replaced the coilpacks and plugs. One of the coilpacks appeared scored, so I figured the problem was fixed. A month went by and the misfire code came back for the same cylinder. This would happen at cold start. This was when I decided to do the carbon cleaning. Inside looked real bad and whether it fixed the problem or not, it certainly was needed. After getting the car back together, I knew immediately that carbon build-up had caused more than a cold misfire. The car was idling and driving so much better than before.

    On my GTI, the car is very modified (KO4 and supporting modifications) with a catch can. I Seafoamed the car as an experiment at some point in its past. The car has 70k miles and I wasn’t experiencing any issues. The valves weren’t that bad, but I cleaned them anyway.

    For the skilled shade-tree mechanic, the job isn’t very hard. Your video on the manifold removal helped very much. Other than a triple square socket and Torx sockets-no special tools are required. I also purchased some engine cleaning brushes and GM top cleaner for the actual cleaning. If someone decided to tackle this, they should set aside at least four hours for the job from start to finish.

    • Paul Barrett
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      Thanks for the feedback. We appreciate it. Glad the Youtube video was helpful please let us know if we can help with anything else.

  2. Bobby
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    I just had a de-carb done on my 2.0T TSI as a result of cold start misfires. Unfortunately, it did not solve the problem. What would be the other reasons for this symptom? A bit of a rough idle on start, clear misfire while accelerating uphill at about 2000 RPMS, 2nd or 3rd gear. Any advice would be most appreciated, Thanks.

  3. |

    My VW has just agreed to cover a carbon clean on my 2011 GTI. It has 80,000Km and has been misfiring when cold and throwing codes. My gas mileage has recently taken a dump – will the cleaning bring my mileage back up to what it was before the issue presented itself? Thanks

    • Paul Barrett
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      Tough to say for certain but carbon can affect fuel mileage. It will no doubt help just depends on how much. Only way to find out how much it will change your mileage is to get it done and see. Hope it gets you back to the original mileage.

    • How did Volkswagen agree to cover the carbon clean, they want to charge over $1300 to clean it. Very disappointed!
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      I replied

  4. Mitch F
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    Paul,
    What a wonderful no Bull service you are providing Audi and VW enthusiasts!
    The gas milieage on my 2009 CC recently dropped about 20 percent. When new it was well above the 31mpg EPA highway rating, usually in the 34-38 mpg range.
    With 72k miles, I will try the intake and injector cleaning. The car has been very well maintained and I can’t think of anything else that would so greatly impact gas mileage. THANK YOU!

    • Paul Barrett
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      No problem. Glad we could help. Please let us know if we can help with anything else.

  5. Frank Johnson
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    Hi, I have a 2010 VW Jetta 2.0t Wolfsburg. Towed it in to VW and they replaced PCV, intake manifold, injectors and did decarb. They then said I needed a Rear main seal replaced. Drove it for one day and took it back because a new noise developed. They pulled the tranny again and said I needed a new DMF. When they finished they heard a new sound and said it may have a bad transmission. Regional VW tech said it was not transmission but #4 cylinder issue, rod bearings I believe. They are tearing down lower engine to inspect. If it’s damaged they say I need a new engine. This whole experience makes no sense. Is it possible they damaged or introduced some FOD into the engine when they were doing other repairs. No fault codes for DMF or from the cylinder.

    • Paul Barrett
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      Your situation sounds complicated and Im sorry but I dont think I can shed anylight on it. Most likely replacing the Flywheel didnt cause any other issues. If you have bottom end issues there is not really anything anyone could have done to cause this. Just a freak occurrence. Sorry to hear about your troubles.

  6. Kaveh
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    I had this problem in my Tiguan 2.0 TSI. Cold misfiring after 100Km. Dealer changed one of Injectors! but problem wasn’t solved. Recently I had a seafoam run in manifold and now engine working like a charm !

    • Paul Barrett
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      Awesome. Seafoam has the potential to help but its a temporary bandaid. You will want to have the manifold removed and clean the valves. They generally would have recommended this when replacing injectors.

  7. Paul
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    Hi there and great job you doing dude!!
    I have a problem with cold engine (only) its spluttering when cold but when get 90’C its working fine. I’m having 60k miles on my cc 09y. 2y ago I had chenge coils but problem still there. I spot 2 times on dashboard showing me missfire isue and in that time I could feel bad working engine (shakes). But after few seconds its coming back to normal and issue stoping flasing. LOL When warm up working great and no spluttering…. what you think about it mate?

    • Paul Barrett
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      Sounds like its likely to be carbon build up.

      • Paul
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        what you think what price can be for manual cleaning at VW?? I’m thinking to go on servise and I tell them to clean it up because I started having cold eng missfires sometimes….

  8. Eric S.
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    The reason carbon buildup is a problem is it does now allow proper airflow into the cylinder. Even though fuel and air is not intermixed prior to being injected into the cylinder, there does still need to be enough velocity and swirl in the incoming air charge to propogate and maintain the flamefront allowing for a complete and efficient burn. Higher temps dont necessarily allow the problem to resolve itself, however closed loop operation will allow the ECU to tailor the fuel and timing a bit to maximize what its able to do.

    This is not just a VW problem, however the europeans have been much more proactive in dealing with it. My shop is one of the few non-dealer facilities that regularly performs media blasting of intake runners and while I am happy to have the business, it scares me how far behind some of the independant repair facilities are. This is something that ALL GDI engines will require, although variances in EGR management as well as PCV management will vary the intervals, every GDI engine will be needing this service at some point in their lifetime.

    Good site and awesome thread!

    • Paul Barrett
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      Yes this is for sure a direct injection issue. Thanks for the feedback. I appreciate it very much.

  9. Johnnybdrivesfast
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    I had my motor replaced @ 74k due to a timing tensioner failure. Car is currently at 95k – I got the intake manifold code, it’s at VW to get it replaced and they’re saying I need the carbon service. I’m struggling to believe that it needs it after only ~20k. I drive the car pretty hard which I am assuming should help. This is a mk6 GTI btw.

    Thoughts on how/why this is possible? I’m tempted to ask to see the build up before agreeing to do it.

    • Paul Barrett
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      Did they inspect it to see if their was carbon before recommending. They would likely assume its dirty based on the mileage. You might consider having them clean just to prolong the requirement to have this done in the next 40k miles. Keep in mind the additional labor for cleaning shouldnt be much.

      • Scott
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        What amount of additional labor time do you think is normal for a dealer to charge for cleaning the valves while the intake is already out?
        An hour? Two?

  10. shiwei
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    Hi Pro, I want to buy a 2016 Tiguan with 2.0T engine. I am hesitating because of this carbon build up issue.
    Does this 2016 2.0T engine still have the same issue?

    Thank you.

    • Paul Barrett
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      Yes it likely will. Please note that most current model vehicles use direct injection so this is going to be a potential issue.

  11. Serban Bara
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    Hello
    I have a audi a3 1.8 tfsi and I am having a rough idle during the warm-up procedure.The engine feels like it’s gooing to dye and sometimes I have small rpm hiccups. As soon as the warm-up procedure ends (30-40 sec) and my rpm drops to idle (850rpm I think) the car feels smooth as butter.I have no misfire codes.
    Maybe you could help me as I’ve tried everythig, even going to te dealer and they didn’t find anything.
    I’ve just changed: MAF sensor, PCV valve,sparks and coils and the fuel filter…I have also bought a new coolant temperature sensor (a friends recvomandation) but mine reads the temperature alright.
    Thanks a lot

    • Paul Barrett
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      Sounds like you might have carbon build up. Have you looked into that?

  12. Bryan
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    Hi Paul,

    Nice work with the site! Huge help on my fuel injector diagnosis.

    My vehicle has 43k on it. 2.0tsi GLI VW 2012. The dealer wants to clean it up. I have photos of what they said the valves currently look like. The reason they are under the hood is to replace the fuel injectors which are covered under warranty. Should I have the stems cleaned also for $360.00?

    • Paul Barrett
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      Thats pretty steep but they have you in a bad spot as the cost to do it the cleaning on its own would be pretty expensive. I would generally expect most dealers to charge an additional 1-1.5 hours labor for this even more so due to the fact the car at 43k isnt going to be crazy dirty.

      Hope this helps

  13. Redza
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    I heard that people advise to do this once a while if we use higher octane fuel and then rev the engine at higher RPM or drive with the accelerator fully depressed can remove the carbon inside the engine, is it true?

  14. Meaghen
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    I have a 2010 VW Tiguan with a consistent carbon build up- I have had to get it cleaned out every 2-3 months (and I don’t put a ton of miles on my car- maybe 12K per year?). I was hesitant to believe my local service technician when he said this was an inherent problem with the car, but you’ve validated it… it doesn’t seem like I should have to take it in so often though, right? I am going to take it to the dealer in town next. I was told over the phone that the service could cost up to $600… not stoked! Is it possible that the dealer offers the sea foam cleaning as a maintenance option?

  15. Ted Johnson
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    Great article and video.

    One question… The BMW and Mini community actually have a walnut media blasting kit from Bavarian Autosport:
    “Cleaning carbon from intake ports and valves on BMW and MINI turbo engines N54 N55”
    https://www.youtube.com/watch?v=NnMhNXXawjk

    to aid DIY’ers in cleaning their intake valves.

    With all the TSI engines out there, it would seem like it would be profitable for someone in the VW community to offer a similar kit. Any possibility Deutsche Autoparts will be offering a kit like Bavarian Autosport?

  16. Christian Mick
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    Great video! I’ve already replaced my PCV valve, which was my original issue. Still misfires, so I replaced the coils and plugs, still misfiring. So you guys let me know there is another option before I tow my car to the dealership! Thanks!

  17. Tammy
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    My dealer is suggesting a manual carbon flush for my 5 year old pass at waggon.
    They want to charge me 840. That’s crazy high I feel. Am I wrong?
    They also said it would take 4.5 hrs of labor. Is that normal too?
    My car was at the dealer for unrelated issues when I was given it back it wouldn’t start…
    So frustrating. But should i just bite the bullet?

  18. Ed
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    Can adding a Catch Can prevent or improve the carbon buildup on the valves?

    • Paul Barrett
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      It will help slow the carbon build up but at this point it does not seem like a permanent solution.

  19. Ben
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    Hi, thank you so very much for all your Insight I have to get the intake manifold replaced on my 2012 turbo Beetle it only has 15 thousand miles,the guy at the dealership is telling me that the carbon buildup is pretty bad which I don’t understand because it only has 15 thousand miles on it is this possible?Thanks again

  20. Mona
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    Hi, I have Tiguan 2012, with almost 90K, I took car to our dealer for interval service and I asked them to check for the car power as I was feeling it is not as before. There was small hick-up and vibration in motor as well.
    After checking, they told me that this is because of carbon deposit and now they want to change the complete cylinder head.

    Question: Does relay carbon deposit require cylinder head to be changed ?

    or it can be because of sth. else that they want to change the cylinder head. Car is under extended warranty but that does not cover carbon deposit removal

    • Paul Barrett
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      No carbon build up generally would not require this

  21. Tim
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    Paul I have a 2009 CC with 18k and boy were my valves dirty. I’m having an issue trying to get the valves on the number 2 cylinder to close. I’m trying to turn the flywheel but it has built up a great deal of resistance and I can no longer budge it moving clockwise. I’ve removed the plugs thinking it was compression, but now I’m not sure and could use some guidance. Also, if you want to help reattach the triplesquare, I won’t argue…

  22. Étienne
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    Hi, i have a 2015 tiguan with 17k and at cold he is idleling rough enough to make the lift shake. The dealer say its normal all 2.0l does it I dont think à new car shoud shake at idleling…

  23. Mike Pietsch
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    Would carbon cleaning be the procedure for a 2010 GTI with <60k miles that seems to have a bit of a jerk on take off from stop and is otherwise smooth in any other condition?

    • Paul Barrett
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      Tough to say but from what you are describing no.

  24. Adam
    |

    I have a 2010 CC 2.0T with cold start misfires. Fault reads cylinder 3 misfire. Replaced spark plugs and bought aftermarket ignition coils, to no success. I was told to buy coil packs direct from VW, as they have been upgraded due to issues. Bought and installed. Cleared codes, did not reappear at running temp. If the fault reappears in the morning, wth do I do? No codes besides cylinder 3 misfire. Mechanic said fuel injectors were OK. Would this be a carbon issue? Starting to run out of patience and money as I just had a new slave cylinder/clutch kit installed too. Anyone else with this issue?

    • Paul Barrett
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      Sounds like an injector. How were the injectors determined to be ok?

      • Adam
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        Still having the same problem. Local mechanic told me there was no issue with the fuel injectors when scanning but the engine was still misfiring at idle. Put some fuel injector cleaner in at no charge but I doubt that will help anything. Will take to VW for a proper diagnosis within the next week.

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