Misfires, oxygen sensors, and A/F ratios (oh my.)

[psychlow]

When a car misfires in open loop mode, it's usually going to dump a cylinder full of unburnt gasoline and oxygen into the exhaust manifold. If that O2 and fuel remains unburnt, the oxygen sensor will read that oxygen.

When this happens, the ECU is going to think the car is running lean (because lean conditions cause more O2 to escape into the exhaust).

My question is, does anyone know if the ECU have any type of programming to pick up on this type of situation? It seems that if the plugs foul, causing misfire, this would only compound the problem otherwise.

 

[streetrays]

running rich or lean, the ECU usually can't tell too much (it's narrowband). so if you're running stock ECU or standalone, you eventually need a wideband controller that understands output from wideband O2 sensor and then forward the voltage to ECU.

but i doubt stock ECU will be programmable in anyway to change its behavior to handle certain issues like misfires and others.