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-   -   PID value for calculated MAT (https://www.corvetteforum.com/forums/c7-tech-performance/4736948-pid-value-for-calculated-mat.html)

ir0nman11 05-17-2023 06:21 PM

PID value for calculated MAT
 
Does anyone know what the PID address and formula for the calculated MAT (manifold air temp) reading on these cars? The sort that can be inputted as a custom PID reading on torque app for example. Maybe someone that might have hptuners set up could probably read the properties from their preset chart PID list.

Like for example how ethanol % sensor reading is 22-0052 with formula (A/255)*100

Zjoe6 05-21-2023 08:45 AM

Moved from C7 General discussion to C7 Tech/Performance.

d16dcoe45 05-22-2023 03:34 AM


Originally Posted by ir0nman11 (Post 1606637294)
Does anyone know what the PID address and formula for the calculated MAT (manifold air temp) reading on these cars? The sort that can be inputted as a custom PID reading on torque app for example. Maybe someone that might have hptuners set up could probably read the properties from their preset chart PID list.

Like for example how ethanol % sensor reading is 22-0052 with formula (A/255)*100

Isn't there a direct IAT sensor you could log? I know in my LS3 I would log IAT directly. It was a Chevy SS sedan which was known for inaccurate readings because the thermistor (for intake temp) was built into the 5 pin MAF connector, and the MAF sat directly above the radiator which skewed the readings. I divorced it and ran an old style brass GM IAT further down the intake (I had to make a new resistance vs temp chart, but all the info was available online) --closer to the intake manifold and got more realistic numbers, it worked really well. Before I divorced the sensors, idle IATs on an 80 degree day would go up to
160 PLUS which would retard the timing and make the car soggy when pulling away.

Kyle of "Goat Rope Garage" on Youtube explains how to write out the formulas for alot of calculated PIDs, and then how to log them, check him out if you haven't. He covers Gen 3, 4 and 5 (LT) tuning.

ir0nman11 06-01-2023 03:02 AM

You can log an IAT2 sensor, yes. But on the C7 the IAT means nothing in relation to timing. Timing is based on the MAT value, which is a calculated value from an equation using the IAT sensors and ECT (i think there was another sensor but I forget which one)

Bill Dearborn 06-01-2023 05:55 PM


Originally Posted by ir0nman11 (Post 1606688791)
You can log an IAT2 sensor, yes. But on the C7 the IAT means nothing in relation to timing. Timing is based on the MAT value, which is a calculated value from an equation using the IAT sensors and ECT (i think there was another sensor but I forget which one)

The LT4 has 3 IAT Sensors. IAT1 and 2 are colocated with the MAF sensor. IAT3 is colocated with the manifold pressure sensor at the rear of the SC on the driver's side of the car and senses the air temperature of the charge air going into the engine. Its reading is called Manifold Air Temperature.

Bill

96GS#007 06-03-2023 12:44 AM


Originally Posted by ir0nman11 (Post 1606637294)
Does anyone know what the PID address and formula for the calculated MAT (manifold air temp) reading on these cars? The sort that can be inputted as a custom PID reading on torque app for example. Maybe someone that might have hptuners set up could probably read the properties from their preset chart PID list.

Like for example how ethanol % sensor reading is 22-0052 with formula (A/255)*100

It's in HP Tuners but it's a default....ie there's nothing to setup and they don't show the math to get there. Perhaps I'm not understanding your question? This is from my 2019 GS....

https://cimg3.ibsrv.net/gimg/www.cor...6c0a066387.png

mittens 11-30-2023 09:33 AM

Anymore info on this?

16 ZO6 in question. Trying to read boost from OBD2. (Dash logic) I have tried all the possible ways to calculate it, even their standard calculated boost. that's subtracts Baro from the manifold.

I have Verified the Car is reading the Baro correctly. Set a screen to show just the Baro reading. it changes with weather, altitude ect. For example right now its around 99kpa.

set a screen to show just the manifold pressure, and its showing it below that (In vacuum) but bring the car up to 0 reading on a mechanical boost gauge and its only reading 64ish. so that's still in vacuum, not = the cars current atmospheric pressure... It should be close to the outside Baro reading when 0 boost is reading on gauge.

SO there has to be some Math to correct the readying of this sensor or something. Dashlogic is working issue too, but they have not fixed it. If i know what the sensors is doing to come to the manifold absolute pressure, Then I can use that math, to fix the manifold pressure and then subtract the Baro and have an accurate boost reading.

Purposely stalled the car. Manifold Absolut pressure Reads 64kpa with motor off. while Baro is reading 99kpa.
around 5psi boost its reading 84 kpa. and 10 psi of boost it reads 108kpa... its not leanear.. even if I take the 64 KPA we know is atmospheric and subtract that form the manifold. it will be 0 boost reading. but at 5lbs of boost in real life it will read 84kpa-62kpa= 20 kpa which is only 2.9 psi what is the magical multiplier.


It maybe a problem with absolute manifold pressure vs absolute manifold pressure Hi res. does anyone know the difference or the math that is between the two?

Toaks 12-03-2023 05:21 PM


Originally Posted by mittens (Post 1607287859)
Anymore info on this?

16 ZO6 in question. Trying to read boost from OBD2. (Dash logic) I have tried all the possible ways to calculate it, even their standard calculated boost. that's subtracts Baro from the manifold.

I have Verified the Car is reading the Baro correctly. Set a screen to show just the Baro reading. it changes with weather, altitude ect. For example right now its around 99kpa.

set a screen to show just the manifold pressure, and its showing it below that (In vacuum) but bring the car up to 0 reading on a mechanical boost gauge and its only reading 64ish. so that's still in vacuum, not = the cars current atmospheric pressure... It should be close to the outside Baro reading when 0 boost is reading on gauge.

SO there has to be some Math to correct the readying of this sensor or something. Dashlogic is working issue too, but they have not fixed it. If i know what the sensors is doing to come to the manifold absolute pressure, Then I can use that math, to fix the manifold pressure and then subtract the Baro and have an accurate boost reading.

Purposely stalled the car. Manifold Absolut pressure Reads 64kpa with motor off. while Baro is reading 99kpa.
around 5psi boost its reading 84 kpa. and 10 psi of boost it reads 108kpa... its not leanear.. even if I take the 64 KPA we know is atmospheric and subtract that form the manifold. it will be 0 boost reading. but at 5lbs of boost in real life it will read 84kpa-62kpa= 20 kpa which is only 2.9 psi what is the magical multiplier.


It maybe a problem with absolute manifold pressure vs absolute manifold pressure Hi res. does anyone know the difference or the math that is between the two?

I was told by both Dashlogic and a few tuners that it is not possible to read MAT no matter the calculation. I returned mine after trying to figure it out and realized it wasn't possible.

mittens 12-04-2023 10:10 AM

I have used dashlogic on last 3-4 vetts I have had. All reading boost, and manifold temps? This is the only one I have had this issue on. First LT4


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