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Thread: Sensor accuracy?

  1. #1

    Default Sensor accuracy?

    I noticed my sensors are off, including CTS, which is GM type with the Holley GM LSx calibration selected. This has me wondering if the MAT/MAP being off, is due to scaling or something else. Anyone else see a 9*F discrepancy with the Holley calibration for the GM LSx CTS? I checked another LS vehicle in my driveway and the same CTS was showing 69*F via the stock LS1B PCM.

    Sensors:
    CTS - GM LSx type
    MAT & Pre-Intercooler AT - Bosch 0280130085
    Intercooler Coolant Temps - Auto Meter 2259 (Calibration table only goes down to 100°F.)
    MAP - GM 3 bar 12223861 (Currently reads 95 kPa with custom calibration or 97 kPa with Holley 3 bar selected. ECU Baro shows 99.6 and reading from another vehicle was 99 kPa.)

    Images below were made after the vehicle had been sitting for several days. Block/intake temp was 69°F.
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    Last edited by TRP; 08-11-2017 at 07:09 PM.

  2. #2

    Default

    Plugged in another new LS type CTS that I had and it wasn't any better. Not that I can swap the sensor without unbolting the header first. Was going to try creating a custom CTS with data for a GM sensor, but the software won't let me enter decreasing Ohm values for increasing temp values? Actually, I'm not as concerned about the CTS being off as I am the IAT/MAT.
    Last edited by TRP; 08-11-2017 at 09:15 PM.

  3. #3

    Default

    I've never seen my coolant temp reading be the same as ambient temp, even after many days sitting. It's always several degrees higher. How do you know that your little laser pointy thing is accurate? Andrew

  4. #4

    Default

    It may not be 100%, but it was very close to ambient, and was a 100% match to what I read off one of my other vehicles with EFILive, same CTS.

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    15,280

    Default

    Quote Originally Posted by andrewb70 View Post
    I've never seen my coolant temp reading be the same as ambient temp, even after many days sitting. It's always several degrees higher.
    Mine is only 2°F difference when the engine is stone cold. He stated he's not as concerned about the CTS.

    How do you know that your little laser pointy thing is accurate? Andrew
    It's called an infrared temp laser gun, and they're very accurate at measuring surface temperature (as long as you follow the distance instructions).
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    15,280

    Default

    Quote Originally Posted by TRP View Post
    Was going to try creating a custom CTS with data for a GM sensor, but the software won't let me enter decreasing Ohm values for increasing temp values?
    At bottom of Calibration Table, enter "Sensor Resistance-Ohms" from low Ω to high Ω (from left to right).

    Actually, I'm not as concerned about the CTS being off as I am the IAT/MAT.
    If you're not sure of your custom sensor's calibration data, use Holley's MAT/IAT sensor (LINK), and select it in the Thermistor Type drop down menu.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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