I was reading through different posts and was wondering if anyone could explain what the difference between the 1, 2, 2.5 bar systems and how they work. I just started getting into tuning and im doing some reading and being a computer science/ programmer i have a few cool ideas, but have to learn how our ecu runs.
Thanks
1 bar:
Perfect vacuum to atmospheric pressure - or - (-14.5psig(depending on altitude, can differ) to 0psig)
2 bar:
Perfect vacuum to 1 bar positive pressure - or - (-14.5psig(depending on altitude, can differ) to +14.5psig)
2.5bar:
Perfect vacuum to 1.5 bar positive pressure - or - (-14.5psig(depending on altitude, can differ) to +21.7psig)
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michael cassatt wrote:I was reading through different posts and was wondering if anyone could explain what the difference between the 1, 2, 2.5 bar systems and how they work. I just started getting into tuning and im doing some reading and being a computer science/ programmer i have a few cool ideas, but have to learn how our ecu runs.
Thanks
Map sensors use a piezo crystal, that when pressure is applied to it, there is generated electric field and a subsequent voltage potential that is generated. Almost all map sensors read 0V to 5V for 0 to "x" bars of air pressure. If you want more information, you can read this post.....
CLICK
There is a list of pressures and corresponding voltages for different map sensors.
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ok, so the a stock ecotec has a 1 bar system correct. So is there any way of making it a 2 bar or even a 2.5 bar, without doing the fake?
michael cassatt wrote:ok, so the a stock ecotec has a 1 bar system correct. So is there any way of making it a 2 bar or even a 2.5 bar, without doing the fake?
Yes, if you can get your hands on a ECO SC reflash PCM (its 2.5 bar), but the downside is you can't tune or modify it in any way as its locked out.
P&P Tuning
420.5whp / 359.8wtq
So, it doesnt have anything to do with how you measure the air? When is our ecu limited to a 1 bar when it is able to measure 2.5 with the reflash then?
michael cassatt wrote:So, it doesnt have anything to do with how you measure the air? When is our ecu limited to a 1 bar when it is able to measure 2.5 with the reflash then?
The reflash requires a new TMAP that reads up to 2.5 bar.
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How hard would it be to program the ecu to read a new sensor that can read a 2.5 bar, without getting the reflash?
Im good at programming so if i knew what language the reflash was in and what all they changes it makes, i could possibly write my own without locking the ecu to farther changes like the reflash does.
If anyone had this information it would be great.
Well, i dont know how... but frankly if you pulled that off and made it distributable... there are a lot of members on here who would cream their pants
I doubt anyone here even knows what processor the PCM uses. A programming language is simply a crutch to make life easier in turning instructions into assembly/machine code. Knowing the language the code is written in does you no good when you have no access to the source code itself. If I were to guess, though, they probably do a great deal of programming in both C AND assembly.
No offense, but without completely understanding the hardware you're working with, I highly doubt you will get anywhere with this. You would be better off like Ron and build your own PCM from scratch.
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The type of processor in each unit probably varies by model, and by year, and possibly by options. Since GM is good at controlling costs and making everything the same.
I wouldn't doubt that the thing is written entirely in assembly.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
I highly doubt that they wrote the whole thing in assembly, if you have ever worked in assembly it takes forever and isn't very efficient. I'm finishing my second year of a programming major and we spent less than a week talking about assembly and most people cant even read it let alone program a cars ecu using it.
More than likely they used either C or C++.
Whalesac wrote:
No offense, but without completely understanding the hardware you're working with, I highly doubt you will get anywhere with this. You would be better off like Ron and build your own PCM from scratch.
Was that a pure race car or a daily driver?
michael cassatt wrote:I highly doubt that they wrote the whole thing in assembly, if you have ever worked in assembly it takes forever and isn't very efficient. I'm finishing my second year of a programming major and we spent less than a week talking about assembly and most people cant even read it let alone program a cars ecu using it.
More than likely they used either C or C++.
That must be the difference between CS and Engineering. For the more complicated subroutines, it is likely that they use C, but for I/O implementation, assembly would be faster and more efficient than relying on the compiler. If you don't have any experience with DSP and are interested in this kind of stuff, I would reccommend taking a class or two on it first.
michael cassatt wrote:Whalesac wrote:
No offense, but without completely understanding the hardware you're working with, I highly doubt you will get anywhere with this. You would be better off like Ron and build your own PCM from scratch.
Was that a pure race car or a daily driver?
I don't know if he ever finished it, but it was based off of Megasquirt hardware, yet was intended to be Plug-n-Play with the Jbody harness.
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michael cassatt wrote:ok, so the a stock ecotec has a 1 bar system correct. So is there any way of making it a 2 bar or even a 2.5 bar, without doing the fake?
You have only two ways of doing this....the fake where 0-5v = vacuum to 2.5bar instead of the vacuum to atm. it was, or the other way which is a reflash of the ECU. I'm sure trying to reprogram the factory PCM will not be possible without extensive info that I'm sure wont be had. I wish you all the luck....
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
I don't need to be dead to donate my organ.
