Tsi cold misfires explained

[Music] hi everyone and welcome back to a new episode of diagnose dan today we are working on a Skoda with a Volkswagen TSI engine Skoda is part of the Volkswagen Group and their cars are equipped with Volkswagen engines now this car came into my shop yesterday with cold misfiring problems now when I get a TSI into my shop and the customer complaint is about cold misfires I immediately think about carbon buildup on the intake valves a lot of cognition ZnO that carbon buildup on the intake valves of direct-injected engines can cause called misfires but only if you know why now in this video we're gonna do a few things at first we're gonna take a look at the intake valves on this TSI engine and see if there's really carbon buildup that might be causing our cold misfires then I'm going to explain why there is carbon buildup on the intake valves of direct-injected engines and then you'll learn why the carbon is making this TSI engine misfire when it's cold and finally we're going to try and clean the intake valves of this TSI engine using two different methods the first method is cleaning the intake valves with my blaster I'm going to blast one cylinder and then I'm going to reassemble the engine and then we're going to try a product called revive revive is claiming to remove carbon deposits from the inside of turbo and non turbo gasoline engines now if this is true and this product works that would be awesome because blasting the intake valves is a very labor-intensive job and this would save you a lot of time does it work I don't know but uh let's find out together [Music] we're going to start out by taking a look at the intake valves and see how bad the carbon buildup of this particular engine really is I already partially removed the intake manifold and hang it to the side so we get access to the intake ports and we can take a look at the intake valves with a borescope in this video I'll be using the Alltel borescope that came with my Mexican [Applause] I'm gonna talk you through this picture and explain what you're seeing because the carbon buildup is debt bad inside this intake port that a lot of parts are beyond recognition we're looking down upon the intake valve and you can see the round shape of the valve seat in the far distance this is the valve seal with the valve stem and you can see that they're totally beyond recognition and totally covered in carbon now I'm gonna start by saving a picture for the customer before we take a closer look at that valve so let's push the camera a little bit further and you can see this is still the valve stem how bad the carbon buildup really is now that looks pretty nasty now let me explain to you why there is carbon buildup on the intake valves and inside the intake ports of direct injected engines in this animation we've got two engines a direct injected engine and an indirect injected engine although there are many differences between these two engines to understand the carbon buildup inside the intake of a direct injected engine we need to take a closer look at the placement of the injector in the direct injected engine the fuel is sprayed directly into the combustion chamber that's why this engine is called direct injected engine on a conventional in direct injected engine the fuel is sprayed into the intake system before the combustion chamber and before the intake valves engines need to suck in air in order to operate but with this air comes contamination like oil vapor that is being sucked in via the crankcase ventilation on a conventional engine fuel is constantly being sprayed into the intake and thereby cleaning the intake ports and the intake valves but on a direct injected engine there is no fuel passing the intake system and therefore over time the contamination will start to build up inside the intake ports and on the intake valves in the form of carbon now over time this will seriously start to affect the performance of your engine in order to understand why TSI engine has got caught misfires when there's carbon buildup in the intake we first need to understand that a direct-injected engine can run on many different modes now not to overcomplicate this video we are gonna stick to the two main modes being stratified mode and homogeneous mode right now the engine is running in homogeneous mode in this mode the fuel is injected near bottom dead center this way the fuel and air have got lots of time to mix into a stoichiometric mixture which is easy to ignite for the spark plug in this mode the engine is the most powerful so the homogeneous mode is being used for high engine loads but also when the engine is idling because you want high torque available to get the car moving from standstill position let's switch the engine from homogeneous to stratified mode in this mode then you can run on a very lean mixture because of the lean mixture the engine is also less powerful in this mode so this mode will only be used under partial load conditions like driving on the highway in this mode the engine is also more fuel efficient the downside is that a lean mixture is very hard to ignite for the spark plug so the engineers had to come up with a clever solution to ignite the lean mixture let's switch this engine from homogeneous to stratified engine mode now pay attention to this flap inside the intake manifold when we select stratified engine mode you will see the intake air is forced to take a certain path into the cylinder now because of this path and because of the shape of the piston the air is guided towards the spark plug now because the fuel is injected on the very last moment this vortex carry a part of the view towards the spark plug creating a rich mixture surrounding the spark plug which is easy to ignite is igniting rich mixture will set up a chain reaction and burn off the lean mixture now that's how this engine can run on a very lean mixture so the intake on a direct-injected engine is engineered in a very specific way to make sure the air fuel mixture reaches the spark plug now if there is carbon build up inside the intake ports and on the intake valves this might disturb the airflow in a way the mixture no longer reaches the spark plug causing a misfire now this effect is greatest at low rpm when the air speed is also low and when the engine is cold because a colder mixture is already harder to ignite so basically the biggest chance of misfiring because of carbon buildup is at a cold idle but in the beginning of this explanation I told you guys a direct-injected engine doesn't idol in stratified mode because you want high engine torque to get the car moving from a standstill and you are a hundred percent right but there is one exception the cold startup when an engine is cold we need to enrich the mixture to make sure the cold mixture easily ignites in the old days we did this using a choke on modern engines we make the mixture richer during the warm-up phase but a direct-injected engine can do a cold startup with a lean mixture saving a lot of fuel during the warm-up phase this is achieved by injecting the fuel at the end of the compression stroke when the air is squeezed together and because of this already warmed up now this only works if the airflow carries the air mixture towards the sparkplug when there is carbon buildup the airflow is disturbed and the engine will misfire the misfires will disappear when the engine is warmed up and switches over to homogeneous mold now this my friends is the real reason for Tia's eyes having called misfires right now I'm going to clean the intake port of Silla number one using a blaster cylinder number one is going to be unknown good and later on in the video we're going to compare this cylinder to the other three we're trying to clean with a chemical called revive now an important thing to know is that all cylinders or intake ports have about the same amount of carbon buildup in this video I'll be using the tune-up blasting kit now this kit works very simple it comes with a rubber hose and one end of the rubber hose you stick into the port you're about to clean the other end you hook up to a vacuum cleaner inside the hose there's a hole which you can stick your blaster into and you can start cleaning your intake port now this system uses granilith now the excess Grendel it is being sucked up by the vacuum cleaner now the great thing about using Grendel it to bless your intake port is if there stays any material behind this can be dissolved with a neutralizer so nothing stays behind that could potentially damage your engine [Music] [Music] [Music] [Music] [Music] and um blasting cylinder number one and now it's time for you guys to see the end result while I was blasting I was checking my progress using a camera now I deliberately left a little bit of carbon behind just to see that every vibe doesn't entirely clean the other three cylinders does it at least clean a little bit of carbon I left behind in the intake of cylinder number one [Music] [Music] in the next step I'm going to reassemble the engine then we're going to treat the engine with revive now I've got to be a hundred percent honest revive doesn't claim to clean the engine in just one treatment neither does it speak about the intake valve suggest generally speaks about removing carbon from the engine but the reseller I got it from he was very confident about the product and he said he had some great feedback and it seemed some great results of himself so I really hope this works because blasting an engine is very labor intensive and this product could save me a lot of time and the customers a lot of money [Music] [Music] [Music] [Music] you you unfortunately the product didn't work as good as I hoped it would now it did have some effect but not nearly enough to call this a repair now really hoped it would because now I'm stuck to blasting those other valves again now it's revived totally useless well I guess not if you're an owner of a direct-injected engine and you use this on a regular basis I guess you can stop the carbon from building up in the first place now I really hope you enjoyed this video and if you want to learn more please subscribe to my channel and we ate a little bell you will get a notification each time I post a new video and remember diagnosed then fix it again see you next time guys you [Music]

Channel: DiagnoseDan

Views: 348,019

Keywords: die autodoktoren, the humble mechanic, tsi, explained, scannerdanner, intake valves, scotty kilmer, revive, volkswagen, carbon build up, south main auto, Volkswagen, Deutsche autoparts, Pine hollow auto diagnostics, the Car wizard

Id: sN-DYl_pZ6E

Length: 20min 9sec (1209 seconds)

Published: Sun Mar 01 2020