dgz924s

What will happen if the O2 sensor is deleted? Car run ok? TIA! Dal

david fracolli

If you just delete it the car will default to a set fuel map. Car will run rich and gas milage will suffer.

dgz924s

Thanks David! So can this be leaned out and remain deleted or is it just better to leave alone? Dal

jabbadeznuts

Dal, I don't think that it can be leaned out unless you have a stand alone ECU/DME setup. It goes to a default for a reason.

Charlotte944

The Bosch DME is designed with a built-in "fail-safe" for the O2 sensor input.

During normal operations the DME "reads" the O2 sensor to determine how well fuel is being burnt in the combustion chambers. If the exhasut gas is too lean, the DME richens the mixture, and if the exhaust is too rich the DME will lean the mixture.

Should the O2 sensor fail, or if the signal from the sensor is not valid (like when you first start the engine), the DME uses a "canned" or preprogrammed value for the O2 sensor input. This value is about 0.45 volts, which is just on the rich side of an "ideal" 14.7:1 fuel/air ratio. This value was chosen to insure the fuel/air mixture never goes lean and cause the engine to detonate (ping or knock).

Because this "safe mode" mixture is rich, running the engine in this condition not only wastes fuel, but given sufficient time this mixture will also destroy the catalyst bed in the catalytic converter, which will cause an increase in back pressure, which causes a further decrease in fuel mileage, increased carbon build up in the cylinders, plug fouling, increased emissions, higher engine temperatures, and so on.