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Old 10-08-2012, 07:00 AM   #3
The Radium King
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Join Date: Apr 2010
Location: Canada
Posts: 3,149
i can help a lil bit. ecu works something like this:

- air flows past maf
- ecu converts maf signal into air quantity
- ecu uses engine load to select pre-programmed table from memory
- ecu uses air quantity and rpm to look-up amount of fuel to administer from table
- ecu then looks at o2 sensor to determine how much uncombusted o2 remains in exhaust
- ecu modifies amount of fuel administered based on o2 sensor data; this is short term fuel trim
- if stft remains constant, it gets programmed into long term fuel trim; this is your ecu learning
- ecu has ability to manage trims up to 25%; this determines how many modifications you can make to your intake and exhaust.

uncertain what the other trim readings mean, but i *assume* they are trims for different engine load states.
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