Thanks for all that info and the pictures, gives me a lot better idea of how it all works. I do not have the skills to build on myself so I would have to get one already made up. The relay would be necessary too because of the carbed status of the car now. I will go to the website and look more into it. Thanks again!
3.8l ecm will it work
- Thread starter level3porkproducer
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To add to the megasquirt nutshell. (please correct me if im wrong with any of this)
The megasquirt works by knowing a few charactoristics about your engine (from the sensors,) doing some math, and then the output of said math is sent to the injectors. First it knows how fast your engine is turning in rpm (no sensor, just a wire from dizzy to computer) and it knows the size of your engine (you input this value from your laptop.) With this, the megasquirt does some geometry (that thing you slept in) to find the exact amount of "volume" of Air that your engine *COULD* move through it at a given rpm. Example: a particular engine is calculated to move 100 "units" of air at 1000rpm, and 200 "units" of air at 2000rpm and so on. With this number, the computer can do the math to find out how much fuel is needed to turn 100 "units" of air into a 14.7:1 air-fuel ratio, or any combination of "units" or air-fuel ratios. Example: to make 100 "units" of air turn into a 14.7:1 air-fuel ratio, you need 10 "units" of fuel. So the injectors inject 10 units of fuel and WAM BAM you have fuel injection.
However, the numbers that the comptuer first gets are a LIE and are totally useless
. This number is assuming that the engine is making %100 "Volumetric Efficiency." All volumetric efficiency means is how "efficient" that the combustion chamber is filling up with air. Example: If a single cylinder engine of 100cubic inches takes an intake stroke and gets 50cubic inches of air on that stroke, it has a volumetric efficiency of %50.
So now we must know the volumetric efficiency for the entire rpm range of your engine under the entire load range (load range is messured by a MAP sensor). Its not as hard as it sounds. This is done by you tuning a "volumatric efficiency table" on your laptop or pc. I wont get into how we find those numbers now. Example: we find that at 1000rpm we are %50 efficient, and at 2000rpm we are %65 efficient. So now the computer takes the numbers it found originaly (the useless ones) and scale them down by %50 and %65, respectively.
I hope this helps.
The megasquirt works by knowing a few charactoristics about your engine (from the sensors,) doing some math, and then the output of said math is sent to the injectors. First it knows how fast your engine is turning in rpm (no sensor, just a wire from dizzy to computer) and it knows the size of your engine (you input this value from your laptop.) With this, the megasquirt does some geometry (that thing you slept in) to find the exact amount of "volume" of Air that your engine *COULD* move through it at a given rpm. Example: a particular engine is calculated to move 100 "units" of air at 1000rpm, and 200 "units" of air at 2000rpm and so on. With this number, the computer can do the math to find out how much fuel is needed to turn 100 "units" of air into a 14.7:1 air-fuel ratio, or any combination of "units" or air-fuel ratios. Example: to make 100 "units" of air turn into a 14.7:1 air-fuel ratio, you need 10 "units" of fuel. So the injectors inject 10 units of fuel and WAM BAM you have fuel injection.
However, the numbers that the comptuer first gets are a LIE and are totally useless
. This number is assuming that the engine is making %100 "Volumetric Efficiency." All volumetric efficiency means is how "efficient" that the combustion chamber is filling up with air. Example: If a single cylinder engine of 100cubic inches takes an intake stroke and gets 50cubic inches of air on that stroke, it has a volumetric efficiency of %50.So now we must know the volumetric efficiency for the entire rpm range of your engine under the entire load range (load range is messured by a MAP sensor). Its not as hard as it sounds. This is done by you tuning a "volumatric efficiency table" on your laptop or pc. I wont get into how we find those numbers now. Example: we find that at 1000rpm we are %50 efficient, and at 2000rpm we are %65 efficient. So now the computer takes the numbers it found originaly (the useless ones) and scale them down by %50 and %65, respectively.
I hope this helps.
Just to add more bits for those that dont want to take the time to read it all on the official site, here is a 12x12 table that everything pretty much runs off of in MS. This one happens to be AFR target table but the ones for timing and fuel look the same just have different numbers in them. This one is used if you are running an O2 sensor to give a target for it to auto adjust or trim mixtures to if you use those options. You can choose the RPM and MAP ranges to fit your application. If you were doing a race car that say 3000-4000rpms were your critical area you could make most of the table in that area to get the most accurate tuning. Kpa is vacuum/ MAP. 90-100 would be ambient (no vacuum) and 35 would be max vacuum (closed throttle).
While looking at this screen with the engine running the 'active' box is highlighted so you can get an idea of where you may want to make real time adjustments. THere is also some really cool dataloging software that is real handy if you do not have a copilot to make adjustments on the fly.
While looking at this screen with the engine running the 'active' box is highlighted so you can get an idea of where you may want to make real time adjustments. THere is also some really cool dataloging software that is real handy if you do not have a copilot to make adjustments on the fly.
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