From the DSM Technical Information manual, in describing the way the ECU controls fuel trim and injector cycle:
If the oxygen sensor shows lean, the short term compensation goes rich and multiplies the pulse width from long term memory in that cell by a facvotr greater than 1. if the sensor shows rich, the short term compensation drives the pulse width narrower by multiplying by a factor less than 1. (perhaps .97) The short term compensation can multiply the pulse width by as much as 1.25 or as little as 0.75 to compensate for lean or richh conditions. In this way, the short term compensation can increase pulse width by up to 25% (by multiplying by 1.25) or decrease pulse width by up to 25% (by multiplying by 0.75)
Example: pulse width 0.05 x 1.25 = 0.0625 (increase of 25%) pulse width 0.05 x 0.75 = 0.0375 (decrease of 25%)
So it appears, that by the Technical Manual, our ECU can actually compensate for up at a 25% change in injector size by increaseing or decreasing the pulse width, rather than the 20% i've heard quoted so often. Just thought this would be interesting information to share.
______________________________________ -Dino Yancey I'm so bad, i should be in detention.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
#3638, "RE: For all you injector and afc psycos..." In response to Reply # 0
Is that so? Then how does the AFC affect the fuel trim (indirectly)? It modifies the MAP output to the ECU, and so the ECU sees a lower/higher MAP than it is, and then the ECU will do what? control pulse width for the injectors? orrrr?
___________________________ l e o n 1995 Eagle Talon ESi-T Boost Cautiously...
#3639, "RE: For all you injector and afc psycos..." In response to Reply # 1
I'm just going to say "Yes."
It modifies the MAP input to the PCM and forces it to narrow or expand the pulse width of the injector. I think ? ______________________________________ -Dino Yancey I'm so bad, i should be in detention.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
#3640, "RE: For all you injector and afc psycos..." In response to Reply # 2
Since the AFC will indirectly affect the pulse width, then the ability for the ECU to compensate for 25% larger injectors won't apply?? unless the O2 sensor read out also plays a role..?
___________________________ l e o n 1995 Eagle Talon ESi-T Boost Cautiously...
#3641, "RE: For all you injector and afc psycos..." In response to Reply # 0
Actually, you beat me to it! The Latest Mopar release says that most Chrysler ECUs can compensate for at least 25% increase in Injector size. I have some more numbers at home, I will post them as soon as possible.
Guy RS_Guy
Keep all your fingers crossed people! Looks like it's all falling in place finally... I might actually be *driving* my car soon! Its only been 5 LONG months...
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