Was reading up about AFM(Air Flow Meter) , MAP(Manifold Absolute Pressure) & MAF(Mass Air Flow)
From what I can see , reading here and on the web
Supra TT Jspec uses a MAP setup
Supra TT UK/USDM use a MAF ; not too sure if it is different for VVTI or Non VVTI? Hotwire sensor I presume?
RB26 uses a AFM
Looking on Wikipedia
MAF -- When a MAF is used in conjunction with an oxygen sensor, the engine's air/fuel ratio can be controlled very accurately. The MAF sensor provides the open-loop predicted air flow information (the measured air flow) to the ECU, and the oxygen sensor provides closed-loop feedback in order to make minor corrections to the predicted air mass (Hot wire sensor or Vane meter sensor typically used)
MAP-- A manifold absolute pressure sensor (MAP) is one of the sensors used in an internal combustion engine's electronic control system. Engines that use a MAP sensor are typically fuel injected. The manifold absolute pressure sensor provides instantaneous manifold pressure information to the engine's electronic control unit (ECU). The data is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion. MAP sensor data can be converted to air mass data using the speed-density method. Engine speed (RPM) and air temperature are also necessary to complete the speed-density calculation
AFM-- An air flow meter is used in some automobiles to measure the quantity of air going into the internal combustion engine. All modern electronically controlled diesel engines use air flow meter,[citation needed] as it is the only possible means of determining the air intake for them. In the case of a petrol engine, the electronic control unit (ECU) then calculates how much fuel is needed to inject into the cylinder ports. In the diesel engine, the ECU meters the fuel through the injectors into the engines cylinders during the compression stroke.
Stoichiometry -- One thing I keep see coming up again and again is Stoichiometry; I presume this is in reference to the EGT reading
Gas stoichiometry deals with reactions involving gases, where the gases are at a known temperature, pressure, and volume, and can be assumed to be ideal gasses.
Few Questions
Why are there so many different methods/Sensors to measure AFR; why do all car manufactures not have a standardised method?
Why did Toyota use 2 different setups between UK/ USDM and JSPEC ? Where they just showing off? Ha ha
Is this why a UK Supra requires 2 Oxygen sensors? One is part of the closed loop system to work with the MAF sensor, why does it need 2 O2 Sensors?
Is the Closed loop system and Open loop system only applicable to an MAF and O2 sensor setup?