we've all seen it car rolls upon a dino with 200 horsepower and a few freshly installed engine mods some guy with a laptop sits in there and presses a few buttons some cool noises maybe some flames later [Music] you got 800 horsepower now but how is that even possible it's all in the tomb baby [Applause] [Music] so today i'm going to be talking about ecu tuning what it is how it's done and why you should get your cartoon too [Music] all right you know what let's go through the basics real quick you probably already know how a combustion engine works i mean you clicked on this video so but put simply to make power you need three things air fuel and spark the combustion cycle starts with your piston atop that center or tdc for short as the piston moves down the intake valve opens and it makes your fuel and air get sucked into the cylinder the piston moves back up again compressing this mixture the spark happens igniting it the gases inside the cylinder expand and push the piston back down the piston moves back up again pushing the gases out of the cylinder and the cycle continues simple enough right good now to get the best performance and efficiency you need the right mixture of air and fuel this is called the air fuel ratio or afr for short too little fuel or what's commonly referred to as a lean mixture your engine won't be making any power or overheat and cause a whole bunch of issues too much fuel or a rich mixture again your engine is not going to make the maximum power and your fuel efficiency is going to suffer so your air fuel ratio needs to be just right and your reference point is always going to be the stoichiometric ratio look at me i say big words now this is the amount of air you need to completely burn let's say one gram of fuel and it's going to be different for every kind of fuel for example to completely burn one gram of gasoline you need 14.7 grams of air that's an air fuel ratio of 14.7 to 1 or just 14.7 but here's the thing that's not where your engine makes the most power at wide open throttle that's too lean it's happy place is actually around 12.5 or so at idle 12.5 is probably too rich your engine might have a smoother idle at around 14. and if you bolt it on a turbo or something you might want it way richer than 12 when your car's on boost and much leaner when you're not in boost so it's not just one afr value it's actually a big table of afr values this is usually called the fuel table or fuel map every cell is going to have an afr value for a given engine speed and load let's say you're at 2000 rpm cruising down the highway so low engine load versus 2000 rpm going up a hill you will have a different afr value in each of those situations to get the maximum power and efficiency in both scenarios good now that we've covered air fuel ratio let's talk about spark the timing of that spark or what's called the ignition timing is also very critical if the spark happens too late the piston might be too far down the cylinder already and you're not gonna make any power if it happens too soon your piston might have to work against the expanding gases on its way back up which can cause detonation and engine damage for maximum power you actually want your piston to be two degrees past off that center when the pressure inside your cylinder is at its maximum but here's the thing two degrees passed off that center is way too late for the ignition system to fire off that spark because the air and fuel mixture inside your cylinder doesn't immediately explode when the spark goes off it actually takes time for the flame to travel through the cylinder and ignite all the fuel that's there this is called the ignition delay so to get the maximum cylinder pressure when your piston is at two degrees past top that center you need to fire off that spark well in advance so you need advanced timing and typically that's around 15 degrees before top dead center that way by the time the piston reaches 2 degrees past off that center the entire fuel mixture is ignited and the cylinder is at its maximum pressure but just like the air fuel ratio the 15 degrees advanced timing isn't a constant as the engine speed or rpm increases the spark needs to happen earlier because the piston is traveling faster so you need more advanced timing higher octane fuel you need more advanced timing because of the slower flame speed in boosted applications you're going to have a higher density air fuel mixture so the flame speed is going to be much faster in that case you need to the ignition timing so the spark needs to happen later when the piston is closer to top dead center and that's why you also have a table for ignition timing with different values for every engine speed and load now back in the day when cars use distributors and carburetors instead of electronic ignition and fuel injectors all you needed to fine tune your air fuel ratio and ignition timing was a screwdriver the timing light and a lot of experience you would mess around with the distributor or the screws and jets and springs on the carburetor until you made more power or blew your engine either way it was pretty quick but those days are gone and the cars that use that kind of technology are just sitting in some boomers garage you and i aren't allowed to touch them so don't even worry about them starting in the 80s and 90s car manufacturers started to use something called the electronic control unit or ecu for short this is basically a computer that's coded to control pretty much everything it receives signals from sensors and actuators all over your car in your engine the code then reads those signals and compares the actual values with the target values on those tables or maps that i just talked about so for example if your mass air flow sensor or throttle position sensor is telling your ecu that you're at 40 engine load and the crank position sensor is telling your ecu that your engine is at 3000 rpm the ecu then looks up the afr value for 40 engine load and 3000 rpm and compares it with the afr value that's coming from your oxygen sensor and your exhaust system it then makes the necessary adjustments to make sure your car is running the way it's supposed to so if the afr value coming from your oxygen sensor is 13 while the table says it's supposed to be 11.5 your ecu knows that your engine's running too lean so it sends a signal to your fuel injectors to stay open longer to add more fuel this feedback mechanism is pretty much how everything else is done too like if your engine starts to experience some engine knock or detonation the ecu will receive a signal from your knock sensors it then sends a signal to your ignition system to timing to protect your engine and stop engine though so to tune your ecu the tuner needs to make changes to the code and the values on those lookup tables and that's how they get to optimize things like air fuel ratio and ignition timing across all engine speeds and loads so let's say you increase your air flow by adding a cold air intake the tuner would then go in add a bit more fuel to match the airflow and that would give you more power now let's say you added a turbocharger the tuner would make changes to the ignition timing so you don't blow your engine on the first pull and adjust your afr and boost pressure to make sure you're getting the most out of your turbo without destroying your engine you can even tune it for e85 if you wanted to you can unlock all the power and potential that engine has to offer and honestly in some cases you can get more power out of your engine even without making any physical modifications just with the tune i'm serious it's like free horsepower now most tuners would tune your car on a dyno there are a couple different types which i'm not going to get into in this video but the point of using a dyno is to make steady state tuning easier the dyno would pretty much keep your car at a certain rpm while you tune it for a different engine load although not impossible with road or track tuning but it's very hard to do and there's always that safety factor but you can't exactly mimic the road or track on a dyno you know the airflow the temperature and the fact that the car is moving so there are pros and cons to both but whatever method of tuning you go with the interface the software the technique you need to keep in mind that tuning requires a lot of learning and experience and adjusting boost pressure air fuel ratio or ignition timing are really just scratching the surface like there are way more tables and maps than the fuel and ignition tables that i just talked about you can do so much more like adding two-step launch control add or modify your traction control and once you start diving into this thing you realize how massive of a rabbit hole toning actually is that's why most tuners specialize in a car on an engine family and just get really good at it because there's just not enough time to learn everything there is to learn another thing you're going to realize is that power runs are actually a very small part of tuning most of the time it's actually spent doing steady state tuning cold start idle stuff like that and those look boring on camera but power runs are the exciting part and that's what gets the views that's why almost every tuning video is power run after power run and that's it now you should have an idea of how tuning works and what your tuner is doing on that laptop hope you're learning something with these explained series videos let me know if i missed anything or if you have any questions in the comments if you've been a follower you know that i try to answer most if not all questions consider subscribing if you haven't already follow me on tik tok and instagram and hey thanks for watching [Music]