Carbon Build up and Cold Start Misfires on 2.0T FSI

May 27, 2015

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Carbon build up on the intake valves of your VW or Audi 2.0T FSI 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 fsi


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 FSI

Paul Barrett


CEO | Ex Dealer Technician | VW Audi Parts Savant | Father | Husband | Chipotle Enthusiast
Creating a VW and Audi Parts Company that Cares


on Carbon Build up and Cold Start Misfires on 2.0T FSI.
  1. Anthony

    Love your helpful videos, on the possible problems to watch for.
    Really appreciate it.
    It makes owning one of these possibly troublesome vehicles a worthwhile proposition, and of course Deutsche my only place for parts.


    • Paul Barrett

      Thank you so much. We are so glad it was helpful. I appreciate your business very much and hope to continue to earn it.

  2. Mark T

    I have a 2006 2.0T which had check engine light come on with misfire codes indicating 2nd cylinder problem and was told by dealer it likely had carbon build up and needed a valve job. I then brought it to an independent VW guy who said to try using only Chevron with Tecron gas exclusively and see what happens. About 200 miles later the the light went off and the cold misfires (sputtering) ceased. Almost 3 years (40k miles) later with no recurrence. Go figure. For anyone in SoCal my VW guy is Johns Foreign Auto in Laguna Niguel

    • Paul Barrett

      The fuel you use has little to do creating carbon build up. Its likely your misfire was not caused by carbon on the valves. Most probably you had an injector that had some deposits that cleared up. You can be pretty certain if you had not had the valves ever cleaned on your 06 2.0t engine you have significant deposits, which are likely diminishing your fuel mileage.

  3. Carl

    Hi I recently got a misfire on cylinder 3 so changed coil pack and all plugs but still misfiring swapped out coils but still on cylinder 3 it then started with multiple misfires so I thought it was fuel starvation changed high pressure fuel pump and cam fuel pump in tank also with new filter still multiple missfires through all the gears the car has 75k oh and it’s a 2005 golf Gti tfsi do you think it would be due to this carbon issue and the manifold needs to come off ? Would the carbon cause missfires like this ? Forgot to mention the odd time it will just go as normal then come back again it’s soul destroying trying to find the problem I want to throw a match on it any ideas thanks

    • Paul Barrett

      Could be carbon or fuel injector related issues.

      • Carl

        Ok thanks I planned on testing the resistance of the injectors if I take the inlet off just to see if one stood out from the others

      • Lionel

        hey so like prevoius poster said i have the same problem only cylinder 3 , coils are fine i can assure that . spark plug 3 keeps blowing i have changed it 3 times already!! any way i can test the injector before pulling manifold so i know that could be the issue. car has 140k and i do believe its never had a valve cleaning job done before.

        what else can cause the plug to blow?

    • |

      Hi! Were you able to solve this problem? I have the same symptoms and can’t figure it out

  4. Daniel

    Hey guys. I was wondering if you can help me with my problem. My car refuses to start. I get a legit crank but no start. The PRNDS blinks and when I put the key in ignition the steeringwheel in the rpm area blinks red and yellowish orange. It’s a 06 gli Jetta 2.0t fsi and it has 150k miles. Please let me know if you know of anything I can do to get back on the road.

    • Paul Barrett

      You will need to have this further diagnosed by a VW specialist


    Hola estimado Paul, tengo un problema con mi auto con motor fsi , empasta las bujias de ollin, pense que cambiando sensores de oxigeno y maf se solucionaria, el carro ya no tiene fuerza y sigue empastando las bujias de ollin, vere si retiro el throttle body para ver si esta sucio o deteriorado.
    Tiene up grades – turbo K04 – inyectores de Golf R – Integrados de Bomba de alta – y varias comas mas.


    Do you have a diy for taking the intake manifold off?

  7. Chad

    Any validity to what I have read concerning oil ingestion caused by faulty cracked leaking valve covers on the FSI Engines? Just started with symptoms of oil ingestion. Exhaust will smoke excessively when car left to idle any longer than about 5 minutes will start to smoke out exhaust when idling and give a big puff of smoke when first excelerating for first time after long idle. Dont see any smoke during normal driving or heavy acceleration. Just staryed out of the blue. Im seeing about 1 quart of oil dissapearing for every 5k miles or so. I know this is pretty low compared to others i just dont want this to get worse and even better would like to fix as there is nothing normal about excessive oil consumtion no matter what evil VW/Audi says. I have read of heavy oil loss being caused by cracked or delaminated unglued portions of the inside of the plastic valve cover. Was very dificult for this owner to track down however they finally found reason for their loss of oil and was valve cover. Should i juat replace cover and see or are there more likely issues i should look into first? On another topic i just read how Lexus is notifying customers owning their dorect injected engines and Lexus is offering a proactive campaign where they will notify customers to bring effected cars into Lexus and they will dismatle clean carbon and replace rings and other items as needed if effected also for FREE. This is the right way to handle such a situation however VW ignores the same issues and worse. VW does not notify customers of likelyhood of failed HPFP CAM followers and failed pumps all of which has happened on my 08 FSI with under 30k original miles. . Cost 2 grand to replace HPFP and upgrade to TSI roller CAM follower. If I can retrofit the TSI Roller HPFP CAM to work on FSI engines fixing permanently, then VW/Audi certainly is capable of it. VW has this arrogant we dont care attitude and expects its loyal customers to flip bills and pay for such fixes and same goes for carbon issue. Really VW? I cant seem to find a valve cover for BPY FSI for any less than $240 however read of people buying same for $130. Is there an aftermarket aluminum valve cover that will fit and work on the FSI ? Place to find OEM cover for closer to $130mm thanks!!

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