Intake Air Temperature Sensor

Applies To:

  • BE5 EJ206, EJ208 (when using single turbo firmware)
  • BH5 EJ206, EJ208 (when using single turbo firmware)
  • GC8 EJ207
  • GF8 EJ205, EJ207
  • SF5 EJ205

Only the GC8/GF8 EJ207 comes with an intake air temperature (IAT) sensor (22634KA071) which is installed in the air scoop. The factory firmware only uses the readings for boost control compensation.

We have modified the firmware to allow Spark Timing Compensation based on IAT and engine coolant temperature (ECT). An IAT is also required to run Speed Density fueling mode.

Adding an IAT

It is possible to add an IAT sensor to your ECU even if it did not come with one originally.

Installation

For best accuracy, the IAT should be mounted in the intake manifold plenum. However, if you are not intending to use speed density fueling, the IAT can be installed anywhere in the air intake duct.

WireECU PinDescription
IAT SignalB136-19Connect to IAT
Sensor GroundB136-31Connect to IAT ground

ECU Modification

Some ECUs do not have the IAT input circuit components populated on the PCB. In this case the datalogged IAT will always read 205 C. The missing components can be added to enable the ECU to read an IAT sensor.

An ECU upgrade kit will be made available with all the required components and instructions to install them.

IAT on MAF Signal

If your ECU does not have the IAT circuit populated on the PCB and you don't have the ability to add the missing components, you can still connect an IAT through the 'MAF Signal' input. Doing this prevents forces the use of speed density mode since the MAF must be disabled and unplugged. It also prevents the addition of a 2nd MAP sensor which would need to use the same input pin.

You will need to add a 1 kΩ pull-up resistor to '5V Power' and another 20 kΩ pull-down resistor to 'Sensor Ground' to generate the correct voltage at the ECU. These resistors can be soldered inside the ECU at the connector header termination points.

WireECU PinDescription
MAF SignalB136-1Connect to IAT
5V PowerB136-121 kΩ resistor to MAF Signal
Sensor GroundB136-31Connect to IAT ground and 20 kΩ resistor to MAF Signal

Configuration

Temperature Sensors

Intake Air Temperature Sensor Calibration
Set according to the temperature vs resistance curve of the IAT sensor you are using. The resistances corresponding to input voltages are as follows:

VoltsOhms
0.000.0
0.1632.3
0.3266.9
0.48104.0
0.64143.9
0.80186.9
0.96233.5
1.12284.0
1.28339.0
1.44399.1
1.60465.1
1.76537.9
1.92618.6
2.08708.4
2.24809.2
2.40923.1
2.561052.6
2.721201.4
2.881374.0
3.041576.8
3.201818.2
3.362110.6
3.522471.9
3.682929.9
3.843529.4
4.004347.8
4.165531.9
4.327397.3
4.4810769.2
4.6418709.7
4.8060000.0
4.96Open Circuit

IAT Sensor on MAF Sensor Input
Set to '1' when an IAT is installed and wired in place of the MAF sensor. Doing this means the original remote-mounted MAP sensor must be used for SD calculation.

Spark Timing - Charge Temperature Compensation

Originally these ECUs did not have any spark timing compensation for intake air temperature. Air temperature greatly affects the knock resistance of a turbo engine so we have patched in a compensation map that can be used to make the tune more reliable.

Spark - Charge Temperature Compensation
Increase or decreases the final spark timing value based on charge temperature (calculated from IAT and ECT).

Spark - Charge Temperature Compensation, Engine Speed Minimum
Spark - Charge Temperature Compensation, Manifold Pressure Minimum
Spark timing charge temperature compensation is enabled when both RPM and MAP values are above these thresholds.

Datalogging

New datalogging parameters have been added to aid in tuning.

Charge Temperature
The result of blending IAT and ECT using the 'Charge Temperature IAT/ECT Blending Ratio' map to estimate temperature of air entering the cylinders.

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