thegipper
New member
That crack was most likely the problem! Here's the rationale as of why. That crack in the pipe is allowing unmetered fresh air to contact the oxygen sensor under some circumstances like idling. The oxygen sensor picks up that unmetered air and sensor a high amount of oxygen in the 'exhaust'. That tells the sensor that the engine is not burning off all the air and is running lean, even though it is not. The ECU adds fuel like you are seeing but under some circumstances that crack isn't pulling in much air, like when the engine is under load and exhaust is coming out of the crack instead of fresh air being pulled in. It then throws a rich code since oxygen sensor is out of normal range on the rich end.
If you pull the EFI fuse after that O2 flange weld and drive it around, I'm very confident that the fuel trims will be back to normal.
I was wondering if it had something to do with it. By the looks of the rust around it, it's seems to be somewhat old or at least, it didn't just "all of a sudden crack" if that makes since. It may have opened up more or....or.....when I went through the car wash the water hitting the hot pipe caused it open up a bunch more??? Who knows, hard to say.
I used a flashlight down the pipe to confirm my weld sealed it up and it did.
New o2 sensors are going in on Friday as long as I can figure out how the hell i'm going to fix that stud that broke.