There's no other way to read voltage across the thermistor. Without the pull up resistor, voltage across the thermistor would always be the reference voltage.
There's no other way to read voltage across the thermistor. Without the pull up resistor, voltage across the thermistor would always be the reference voltage.
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Do you have a schematic for these PCM's? It would be interesting to see how the circuitry for the temp sensors is configured.
I am good buds with CTD.
I verified the 5v with no sensor plugged in. Replaced the sensor with a 5k pot, and adjusted for 2.5v. Measured the pot at 2500 ohms.
I could hook up hpt and get a resistance/temp reading I suppose.
Ha! I better send my ohm meter off to the natl. bureau of standards for calibration! :-)
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Good info to know, still appears the back calculation I did was pretty close...
James Short - [email protected]
Located in Central Kentucky
ShorTuning
2020 Camaro 2SS | BTR 230 | GPI CNC Heads | MSD Intake | Rotofab | 2" LT's | Flex Fuel | 638rwhp / 540rwtq
2002 Camaro | LSX 427 | CID LS7's | Twin GT5088's | Haltech Nexus R5 | RPM TH400
If anyone is curious...here's what I got...a little different than what was posted above, but no much. The 0 and 100% values are just the min/max allowed in the table since I actually calculated -48.8 and 345.9 for those.
Gen 4 IAT on Gen 3.jpg
2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
2023 Durango Hellcat
MikeOD how did you arrive @ your values? Nice
Converted the gen 4 axis to % based on the 2490 ohm pull up resistor that Jabbot said he's physically measured in the PCM.
After that I graphed the Gen 4 temperatures (from my LS3 Camaro calibration) versus % in Excel and put a trend line through it. Best fit I could find in Excel was a 6th order polynomial. After that I had Excel output the equation to the most resolution it could.
Once I had that equation, I popped the Gen 4 % numbers back into it to see how close I was with the calculation (mostly within 3%, one cell was just under 5%), then I used the Gen 3 axis numbers with the same equation to get the results I posted.
I'll put the Excel sheet up when I'm at my PC. I'm on my phone now.
2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
2023 Durango Hellcat
Tx's!
LS3-LS1 IAT transfer corrected -4% from calculated.jpg
Results, I let this settle for a couple of hours. The heater will skew quickly, .96% of the table. Same as before I had the scanner logging prior to plugging the MAF in.
That's with the table/spreadsheet I posted? Nice.
2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
2023 Durango Hellcat
Yes it was, I multiplied your original by .96% & that is the result. A 3.8% error to the ECT & External temp sensors
You multiplied the whole table by 0.96? Post up what you're running for values.
2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
2023 Durango Hellcat
Labels 0.00 6.25 12.50 18.75 25.00 31.25 37.50 43.75 50.00 56.25 62.50 68.75 75.00 81.25 87.50 93.75 100.00
Inlet Air Temp 272.61 216.57 160.32 133.04 116.94 103.51 89.45 75.31 62.09 50.98 41.77 33.12 22.58 7.88 -11.59 -33.11 -38.38
Google Sheets is able to fit a better trendline than Excel, but I'm still trying to figure out how to get the equation back from it with enough resolution to make it useful. The r^2 value in sheets is basically 1, but it's not sharing enough coefficient data, so calculating back goes bananas.
Last edited by MikeOD; 01-25-2015 at 04:14 PM.
You won't find an equation that really fits. It's better to visually line up the break points.
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http://www.facebook.com/dsx.tuning
Just say no to bull s***.
IF YOU WANT HELP, POST A FILE!