While I am waiting for the Variohm Hall effect TPS to arrive, I decided to add an intake air temperature sensor (IAT also referred to as MAT - manifold air temperature in MS / TunerStudio documentation) to my ITB EFI set up. The conversion kit from Al at x-faktory.com doesn't use the IAT sensor and my system worked without it, but without the IAT sensor data the MegaSquirt ECU assumes the intake air temp is 70 deg F and does not adjust fueling to compensate for air density changes as temperature rises and falls.
The first order of business was to carefully remove the vinyl electrical wrapping I had applied to the ECU wiring harness back to the point where I separated signal / sensor wires from power / ground wires.
The short orange wire is connected to ECU connector pin 20 - MAT (IAT) sensor. I joined a 3 foot length of orange 16 gauge wire with a crimp connector.
The IAT sensor has an orange signal wire and a black ground wire which is connected to ECU pin 7 sensor ground which is also used for the TPS, so I used a crimp connector with 1 wire in / 2 wires out to split off the sensor ground for both the TPS and the IAT sensor.
This time instead of re-wrapping the wiring bundles with vinyl electrical tape I decided to use 3/8 inch plastic split wire wrap.
Close up of the IAT sensor with connector and pigtail. This is a GM unit and supported with calibration setpoints in TunerStudio. I found this listed on the diyautotune and summit sites.
The IAT sensor mounted on the base plate of the air filter weather hat on the 1,2,3 bank ITB's.
I updated my EFI documentation for the addition of the IAT sensor signal and sensor ground connections.
With my notebook PC running TunerStudio and connected to the powered up MegaSquirt2 ECU, I unlocked the temp sensor calibration tables and selected "Burn". Then I opened "Calibrate Thermistor Tables", selected "Air Temperature Sensor", selected "GM", then selected "Write to Controller". Then I locked the sensor calibrations and selected "Burn". Now the IAT sensor is calibrated and reading the correct air temperature and ready to use.
