Quoting steveGLS:
Quoting SleepinGVR4:
If I do have an exhaust leak before the 02 sensor, I figured the ECU sees that and dumps more fuel because it thinks my car is running lean.
Thinking out loud here, the O2 sensor is not trying to detect the volume of exhaust gases, so it doesn't care about the lost volume of exhaust gases due to the leak. Plus, if there is an exhaust leak it isn't going to be just the O2 leaking out, or just the O2 staying in the exhaust. The gas as a whole will escape, and the ratio of oxygen to other gases should be unchanged. So I don't see how an exhaust leak would cause the ECU to dump more fuel, as long as the O2 sensor is seeing a representative sample of exhaust gases. No?
That's what I thought Steve. But I was reading something over on Tooners and one of the Mods said that if there is a exhaust leak before the 02 sensor, the 02 sensor sees the fresh air getting in as the mixture being lean so it adds more fuel. According to the guy on Tuners that makes the factory 02 sensor read funny, making the fuel trims never even out and makes your wideband read leaner than it should when in reality my car could be running rich.
That's what I got out of it anyway. I could be way off. Maybe Jeff O. could clarify.