nicetts

Does anyone know what the ECU uses at WOT? Maps, O2, MAF, Combo of, (I would bet that)

RobbyTT

my guess would be maps. John S, where you at?

hoTTub

WOT = Closed loop which = Maps this is my understanding

nicetts

My total guess is maps and O2, but might do MAP also.

john s

The ECU consults many maps to determine fuel injection duration. Do not confuse maps with MAPS (Manifold Absolute Pressure Sensor), a sensor used to improve the accuracy of induction charge estimation. The ECU runs a simulation of induction mass based on throttle position, manifold pressure, barometric pressure, rpm, valve overlap and combustion chamber temperature. A plausibility test is done on the estimation and the MAF sensor reading. MAF readings are known to lag in transitory situations and are discounted. If you're cruising along in 6th gear at 70 mph the MAF reading is validated by the charge estimation. The 02 sensor is used in conjunction with the MAF to adjust the calibration of the injectors. If you suddenly floor the gas pedal a few things happen. The pressure in the manifold rises suddenly to atmospheric pressure. The higher the pressure in the ports the greater the amount of liquid fuel that is stored there. The ECU has a map of throttle angle vs. throttle angular velocity to use in adjusting injection timing to take into account for this. As the manifold fills with air the MAF sensor begins to read this increase in flow rate, however the air is not yet into the cylinders so the ECU, based on charge estimations, still discounts the MAF sensor values. After the manifold pressure and fuel storage has stabilized the MAF sensor readings can again be used, such as in the 6th gear case. Due to richness, O2 feedback is not used WOT. Low gears WOT with the turbocharger are too transitory for the MAF sensor to be used as the controlling signal.