Haltech Sensor Calibration File Request: FC Intake Air Temperature Sensor
06-02-13, 09:12 PM
#1
Sensor Calibration File Request: FC Intake Air Temperature Sensor
After looking through what is included in Haltech's ECU Manager, I have found that it is lacking a profile for the FC's IAT Sensor. The FD one is there, but the FSM states its resistance values are quite different from the FC's sensor. Also, switching to a FD sensor means trying to find a suitable connector and even Ray Crowe says "I got nothing man" when it comes to connectors...
With an ambient temperature of approximately 86 degrees fahrenheit and using the FD sensor calibration file with a FC sensor, ECU Manager reported 32 degrees. Clearly this is not the case nor would such be anywhere near safe for a daily driver due to running excessively rich.
Normally I would just make the calibration file myself, but this is the difficult part: ECU Manager wants a voltage measurement for each calibration point. Unless I am mistaken, the way most standalones work with IAT sensors is that it reads the impedance between the IAT sensor input wire and ground. There is no 5v+ related to this, so how can there be a voltage reading?
Cliff Notes:
I need a FC IAT Sensor calibration file made
ECU Manager wants voltages like when dealing with a Map Sensor
Both FC & FD IAT Sensors only have 2 wires, ground and output to ECU, no 5v sensor power involved
With an ambient temperature of approximately 86 degrees fahrenheit and using the FD sensor calibration file with a FC sensor, ECU Manager reported 32 degrees. Clearly this is not the case nor would such be anywhere near safe for a daily driver due to running excessively rich.
Normally I would just make the calibration file myself, but this is the difficult part: ECU Manager wants a voltage measurement for each calibration point. Unless I am mistaken, the way most standalones work with IAT sensors is that it reads the impedance between the IAT sensor input wire and ground. There is no 5v+ related to this, so how can there be a voltage reading?
Cliff Notes:
I need a FC IAT Sensor calibration file made
ECU Manager wants voltages like when dealing with a Map Sensor
Both FC & FD IAT Sensors only have 2 wires, ground and output to ECU, no 5v sensor power involved
06-04-13, 08:49 PM
#3
I did the math and found the appropriate voltages for the specs in the FSM. Doublechecking myself, I repeated the process with the FD sensor's specs and found them to me within 0.05v of what ECU Manager says. For the two control points I have, 25*C and 85*C, it is close enough. However, something I noticed in ECU Manager is that the ends of the graph are disproportionate with the middle in the manner of a sharp increase in temperature vs voltage near 0v and a considerable drop in voltage compared to temperature near 5v.
Please excuse the crude ascii illustration of this calibration curve. Left is 0v, top is 100*C
_
\-\ _
In the middle, it is relatively linear but steps up considerably at lower voltages (higher temps) and steps down in temperature with equal significance above 4v. With the current information I have, I cannot scale the sensor properly through its entire range.
Would you happen to have impedance readings for more temperature points? ECU Manager uses 0, 10, 30, 50, 60, 70, 90 & 100 degrees Celsius.
Please excuse the crude ascii illustration of this calibration curve. Left is 0v, top is 100*C
_
\-\ _
In the middle, it is relatively linear but steps up considerably at lower voltages (higher temps) and steps down in temperature with equal significance above 4v. With the current information I have, I cannot scale the sensor properly through its entire range.
Would you happen to have impedance readings for more temperature points? ECU Manager uses 0, 10, 30, 50, 60, 70, 90 & 100 degrees Celsius.
06-07-13, 06:05 PM
#5
Using the typical tools of Macgyver's trade found in the kitchen, I have calibration data for the entire range. This data was compiled using a household thermometer and refrigerator for 0-120 and a meat thermometer & hair dryer for 120-185. Voltages were obtained using the following Voltage Divider Calculator:
Voltage Divider Calculator
0°F/-17.78°C:, 272 KΩ (4.982v)
10°F/-12.2°C: 262 KΩ (4.981v)
20°F/-6.7°C: 253 KΩ (4.980v)
30°F/1.1°C: 105 KΩ (4.953v)
69°F/20.5°C: 38.2 KΩ (4.870v)
77°F/25°C: 33.000 KΩ (4.853v)
110°F/43.3°C: 15.6 KΩ (4.699v)
128°F/53.3°C: 13.8 KΩ (4.662v)
170°F/76.7°C: 6.6 KΩ (4.342v)
185°F/85°C: 3.500 KΩ (3.889v)
As you can see, the sensor uses the 4-5v range nearly all of its applicable range. After 175 degrees or so, it knee-jerks and the voltage falls like a rock. I would presume this is so the stock ECU can go "Oh ****, IAT is stupid hot, I better do something really fast.", sorta like a Narrowband O2 sensor. The FD's sensor uses the 0-5v range much better, akin to a Wideband. Makes logical sense as the FD runs much hotter than the FC, so it would need a bigger voltage range.
When tested with ambient temperature of 64 degrees Fahrenheit, IAT sensor reported 62 degrees, well within its +/-10% tolerance. Close enough for me
Voltage Divider Calculator
0°F/-17.78°C:, 272 KΩ (4.982v)
10°F/-12.2°C: 262 KΩ (4.981v)
20°F/-6.7°C: 253 KΩ (4.980v)
30°F/1.1°C: 105 KΩ (4.953v)
69°F/20.5°C: 38.2 KΩ (4.870v)
77°F/25°C: 33.000 KΩ (4.853v)
110°F/43.3°C: 15.6 KΩ (4.699v)
128°F/53.3°C: 13.8 KΩ (4.662v)
170°F/76.7°C: 6.6 KΩ (4.342v)
185°F/85°C: 3.500 KΩ (3.889v)
As you can see, the sensor uses the 4-5v range nearly all of its applicable range. After 175 degrees or so, it knee-jerks and the voltage falls like a rock. I would presume this is so the stock ECU can go "Oh ****, IAT is stupid hot, I better do something really fast.", sorta like a Narrowband O2 sensor. The FD's sensor uses the 0-5v range much better, akin to a Wideband. Makes logical sense as the FD runs much hotter than the FC, so it would need a bigger voltage range.
When tested with ambient temperature of 64 degrees Fahrenheit, IAT sensor reported 62 degrees, well within its +/-10% tolerance. Close enough for me
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SupSai7 (07-04-18)
07-05-18, 07:38 AM
#7
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