|Top Previous Next|
When using a MAP based calibration the AFM is no longer used to measure air flow, but the air temperature part of the AFM is required by the ECU. It is possible to replace the AFM with an IAT sensor to remove the AFM restriction from the air flow, or to relocate the IAT sensor when it can sense the air temperature more effectively.
You will need an electrically compatible IAT sensor and connector with wire. Compatible sensors are from OBDI vehicles (1992-2001 Civic/Integra) or the RSX IAT sensor. The OBDI IAT sensor has a two bolt flange, which is suitable for forced induction, while the RSX sensor is a barbed press-in fitment. A connector can be found in the harness of the same vehicle - there are multiple plugs which will fit the sensor. Make sure you obtain a plug with two wires, not just a single wire.
OBDI air temperature sensor
Wiring the sensor
We are going to splice the IAT sensor wiring into the AFM wiring. The advantage of splicing the wiring in this way is that it is possible to return the car to AFM use by unplugging the IAT and plugging the AFM back in. You should only have either the IAT or the AFM plugged in, otherwise the ECU will not read the air temperature correctly. You may wish to cover the AFM plug to prevent dirt or water from entering the connector.
On the AFM connector remove the tape and identify the IAT wires. They are both at one end of the connector and are red/yellow and green/black. Strip the insulation back and solder the IAT wiring on. The polarity of the wires is not important - each IAT wire can go either to the red/yellow or green/black wire.
IAT sensor spliced into harness
Insulate the connections and replace the plastic wire shield.
Place the IAT sensor where it will effectively read the temperature of the air entering the engine. For NA vehicles this is virtually anywhere in the intake tube. For turbo-charged vehicles the sensor should be after the intercooler - near the throttle or in the intake manifold works. Supercharged vehicles should position the sensor so that it reads the air temperature after the supercharger.
IAT sensor in manifold
Before starting the vehicle switch the ignition on and verify by datalogging that the sensor is reading the correct temperature. There are no calibration changes necessary for the new sensor - just make sure you are using a MAP based calibration.