Kelivin kPa
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Kelivin kPa
Just looking through a 411 bin file and have a question relating to the main ve table. What is a Kelivin/kPa? Can I assume it's air pressure?
- vlad01
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Re: Kelivin kPa
Probably ideal gas law scalar. Absolute temp vs absolute pressure.
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- delcowizzid
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Re: Kelivin kPa
Kelvin is temperature
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Re: Kelivin kPa
That was my first thought till I did a google and noticed it was not kelvin but kelivin. I know the scaler is what someone wrote to represent a scale but I have never heard of kelivin. It sure looks like air pressure starting at 0.08 and ending up at 1.2 so I assume that's bar. The same scaling (not labeled) is used on the spark table and both against rpm.
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Re: Kelivin kPa
It would be a scalar for the amount of temp increase with air pressure. As pressure increases the temp goes up automatically and vise versa. Sounds to me a scalar for temp offset depending on air pressure. It should be part of ideal gas law calculations looking at it.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
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Re: Kelivin kPa
Yes I understand what Kelvin is and pressure and temperature but kelivin is unheard of for anything. Maybe it's an error and meant to be kelvin but to put it in a part of the VE table and Ignition map.
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Re: Kelivin kPa
looks to do what I thought. Would be just a typo
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
Re: Kelivin kPa
I agree, it's a typo.
Coincidentally I am just (barely) far enough into disassembling my car's OS to be able to find the code for this stuff.
At address 456DE there's a function that gets called to look up PID 000B, manifold absolute pressure.
That function reads a value from address FFADB8 in RAM, so I labeled that value Pid_000B_ManifoldAbsolutePressure.
That gets copied to address FFADB6, which in turn gets copied to address FFADB4, which I renamed to VE_MapAxisInput (you'll see why).
It divides the value by 51 before returning it, so I guess the units are 51ths of a kPa, but I wouldn't stake my life on that claim.
There's a function at 456D2 that gets PID 000C, engine speed in RPM.
That function reads from FFA0C0 and divides it by 5, so I labeled that Pid_000C_EngineSpeedIn5xRpm.
The code that uses the VE table reads the Pid_000C_EngineSpeedInRpm and ensures it's between 400 and 8192.
Then it reads the VE_MapAxisInput value and ensures it's at least 15kpa, but it doesn't appear to enforce a max value.
Then it passes those two values and the address of the VE table to a function that does the actual lookup.
Coincidentally I am just (barely) far enough into disassembling my car's OS to be able to find the code for this stuff.
At address 456DE there's a function that gets called to look up PID 000B, manifold absolute pressure.
That function reads a value from address FFADB8 in RAM, so I labeled that value Pid_000B_ManifoldAbsolutePressure.
That gets copied to address FFADB6, which in turn gets copied to address FFADB4, which I renamed to VE_MapAxisInput (you'll see why).
It divides the value by 51 before returning it, so I guess the units are 51ths of a kPa, but I wouldn't stake my life on that claim.
There's a function at 456D2 that gets PID 000C, engine speed in RPM.
That function reads from FFA0C0 and divides it by 5, so I labeled that Pid_000C_EngineSpeedIn5xRpm.
The code that uses the VE table reads the Pid_000C_EngineSpeedInRpm and ensures it's between 400 and 8192.
Then it reads the VE_MapAxisInput value and ensures it's at least 15kpa, but it doesn't appear to enforce a max value.
Then it passes those two values and the address of the VE table to a function that does the actual lookup.
Please don't PM me with technical questions - start a thread instead, and send me a link to it. That way I can answer in public, and help other people who have the same question. Thanks!