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Forum namePerformance/Engine
Topic subjectIAT - how the ECU uses it
Topic URLhttps://forums.2gnt.com/dcboard.php?az=show_topic&forum=i5&topic_id=68641
68641, IAT - how the ECU uses it
Posted by DR1665, Feb-17-04 09:21 AM
I was just curious as to how the differences in IAT affect the performance of the car. Mine had all but come unscrewed yesterday and I was just wondering.

Thanks!
68645, RE: IAT - how the ECU uses it
Posted by REV_GSlow, Feb-17-04 11:19 AM
Intake air temp sensor: Reads the tempurature of the air coming from the intake which tells the computer how to mix fuel/air....i think ;-)
68648, RE: IAT - how the ECU uses it
Posted by Michael_97RS, Feb-17-04 12:51 PM
Originally posted by REV_GSlow
Intake air temp sensor: Reads the tempurature of the air coming from the intake which tells the computer how to mix fuel/air....i think ;-)


Yup, ECU uses it to calculate fuel trims and timing curve.



Exile Racing Technologies: http://www.exileracing.com
una salus victus
It's holding down the garage floor right now.
68673, RE: IAT - how the ECU uses it
Posted by DR1665, Feb-17-04 04:42 PM
Is there a general rule of thumb for how the ECU trims things out cold vs hot? I was being naive and wondered if relocating it to a cooler area might help? A hotter area? I know I know, but this is how we learn things right? :P
68703, RE: IAT - how the ECU uses it
Posted by Michael_97RS, Feb-18-04 03:17 AM
Colder air is denser, and packed with more molecules, colder air needs more fuel.



Exile Racing Technologies: http://www.exileracing.com
una salus victus
It's holding down the garage floor right now.
68704, RE: IAT - how the ECU uses it
Posted by a_miller_76, Feb-18-04 03:42 AM
Originally posted by Michael_97RS
Colder air is denser, and packed with more molecules, colder air needs more fuel. Exile Racing Technologies: http://www.exileracing.com una salus victus It's holding down the garage floor right now.



So then the warmer it is the more it would lean it out? Would that advance your timing? And no, i'm not talking about the stupid ebay "timing advance mod"
68706, RE: IAT - how the ECU uses it
Posted by DarkOne, Feb-18-04 05:12 AM
The IAT is used to determine air density. In combination with the MAP sensor, the ecu determines a close approximation of the mass of thge air coming into the motor. With that info, it determines the engine's current fuel requirements.
68707, RE: IAT - how the ECU uses it
Posted by Corbin, Feb-18-04 05:40 AM
And I wouldn't relocate the sensor. You want it to read accurately. If you really wanted to play with its output, you could add resistors to the wiring. That would have a minimal effect on how the car ran (under most conditions). This is because the ECU primarily uses the O2 sensor to determine fueling when running in closed loop mode. I have some MFI stuff here:

http://www.2gnt.com/www/corbin/mfi.html

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire