Hehe..I dont know anymore :) The more I try and disect this, the more i get confused on how this is supposed to work..Let me try and explain my thoughts...



>We must not be understanding each other...
>How will it know its in boost? Even though the ecu doesn't
>read any positive pressure off the map the map is still
>showing positive pressure to the smc. The map sensor will go
>up and up as boost increases which causes the smc to change
>duty cycle but at the same time not showing any positive
>pressure to the ecu.


From what i know, someone please correct me if i'm wrong, that injector duty cycle( the "on" time that the injector actually sprays fuel), is mainly controlled by the MAP sensor voltage. The more air that the map sees, the longer the injector duty cycle to acompany the the extra air, for proper A/F mixture. Now if the SMC is clamping map voltage, to make the ecu think there is only 0 psi, then how does the SMC increase or decrease the duty cycle? In closed loop, i can see how it can control larger injectors to trick the ecu to lessen duty cycles, just like the SAFC. The SAFC just interpretes the map voltage,and increases or decreases it to change the stock programed duty cycle. Now, at WOT, or open loop, the ecu goes into a preprogramed fuel map, a preprogramed duty cycle that corresponds with engine rpm. Higher rpm means a greater duty cycle, because higher rpm means that more air is getting in there, and needs more fuel. With me? If our map is controlling duty cycle, then how does the SMC decrease/increase duty cycle? The map voltage is clamped at 4.5 or so volts automatically...maybe i'm looking too much into it...I just want to understand how this thing works...
How will the SMC give the proper A/F mix under boost, at different boost levels, not just one set boost pressure..