Which is an example of an external IAT sensor?
Example of changes made in the EPROM chip by modifying the parameter tables, called “maps”: These are some examples of external IAT sensors, which are mounted separately from the MAF sensor.
How can I tell if my IAT sensor is working?
The first one, the IAT response, while it could be in the documentation of the sensor manufacturer or the car manufacturer, the easiest way to know is by using a low-temperature source like ice or a cooling no-residue spray and directly measure the temperature and the resistance.
What kind of resistor do I need for IAT?
Let’s say it measures 4600 ohms, then you may use a commonly available 4700 ohms (4.7k) resistor in series with the IAT. The above procedure is easy if the IAT is separate from the MAF. Otherwise, you will need to use a cooling spray as a source of low temperature for getting the needed equivalent to 50 degrees resistance value.
What does the negative coefficient of the IAT mean?
The thermistor used in the IAT has a negative coefficient, which means that the higher the temperature, the lower the resistance in ohms. That being said, as you may deduct so far, if you want the computer to “think” that air is colder than it really is, then a reading of a higher resistance from the IAT is what we are looking for.
Why are resistors connected to the IAT sensor?
This is, a resistor connected in some way to Intake Air Temperature sensor (IAT), to “fool” the ECM into “thinking” that incoming air is cold, hoping that the ECM will inject more fuel to compensate for the “colder” air. ECMs are programmed to compensate in some way when the air is colder, as colder air carries more oxygen for being denser.
The first one, the IAT response, while it could be in the documentation of the sensor manufacturer or the car manufacturer, the easiest way to know is by using a low-temperature source like ice or a cooling no-residue spray and directly measure the temperature and the resistance.
The thermistor used in the IAT has a negative coefficient, which means that the higher the temperature, the lower the resistance in ohms. That being said, as you may deduct so far, if you want the computer to “think” that air is colder than it really is, then a reading of a higher resistance from the IAT is what we are looking for.
How do you measure the resistance of an IAT?
Add ice until the thermometer goes down to 50 degrees and then measure the resistance of the IAT. Let’s say it measures 4600 ohms, then you may use a commonly available 4700 ohms (4.7k) resistor in series with the IAT. The above procedure is easy if the IAT is separate from the MAF.
How are MAF sensors different from IAT sensors?
MAF is an acronym for “mass air flow.” Unlike IAT sensors, MAF sensors measure air volume with temperature at once. Remember, the MAP sensor above measured intake manifold pressure / vacuum and then estimated air volume with computer software. An MAF actually measures real air volume so that the computer doesn’t need to guess what it might be.
What are the trouble codes for the IAT sensor?
On most OBD1 applications, two trouble codes are associated with the IAT sensor. A code 23 indicates the intake air temp reading is lower than expected. If this code is present, before replacing the sensor you should check for an open circuit to the IAT sensor wiring. A code 25 indicates the intake air temp reading is higher than expected.
What are the trouble codes for the MAP sensor?
On most OBD1 applications, there are two trouble codes associated with the MAP sensor. A code 33 will set if the MAP sensor output voltage is higher than expected (indicating low vacuum) and a code 34 will set if the MAP sensor output voltage is lower than expected (indicating high vacuum).
What kind of wire does a MAP sensor use?
MAP sensors typically have 3 wires: a 5 volt reference signal wire, a ground wire, and the wire that goes back to the engine control unit (ECU).
Example of changes made in the EPROM chip by modifying the parameter tables, called “maps”: These are some examples of external IAT sensors, which are mounted separately from the MAF sensor.