The catalyst requires that the fuel/air mixture is stoichiometric. This means that the mixture is neither rich or lean, it is exactly 14,7 kg air to 1 kg gasoline (Lambda=1). That is why the system is equipped with an oxygen sensor in the forward part of the exhaust system. The sensor is connected to pin 23 in the ECU and is grounded in the ECU via pin 47. The exhaust fumes pass the oxygen sensor. The content of oxygen in the exhaust fumes is measured through a chemical reaction, this results in an output voltage. If the engine runs rich (Lambda lower than 1) the output voltage would be more than 0.45 V and if the engine runs lean (Lambda higher than 1) the output voltage would be less than 0.45 V. The output voltage swings about 0.45 V when Lambda passes 1. The ECU continuously corrects the injection duration so that Lambda=1 is always met. To be able to function the oxygen sensor needs to be hot, this requirement is meet by electrically pre heat the sensor. The pre heating element is fed by B+ via fuse 38 and the main relay, the sensor is grounded in the ECU via pin 50. The ECU estimates the temperature on the exhaust gases (EGT) on the basis of the engine load and the engines RPM. At high EGT the electrical pre heating is disconnected. The lambda correction is masked during the engines first 640 revolutions after start if the coolant temperature exceeds 18℃ (64F) at load ranges over idle and under WOT or 32℃ (90F) at idle.
Other articles related to "correction, lambda correction, lambda":
... are then corrected by multiplication of a correction factor, which is fetched from main fuel matrix (huvudbränslematrisen in Swedish) and is dependable on MAP and RPM ... The last correction is made with the lambda correction, this results in a stoichiometric combustion (Lambda=1) ... The lambda correction is allowed to adjust the calculated injection duration by ±25% ...
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