O2 voltage discrepancy

[csracing]

I'm trying to better understand why my oxygen sensor voltage is so inconsistent on the left bank on my engine. 2007 Mustang GT and the log file is attached. Note that the right bank shows rich for essentially the entire run whereas the left bank goes from rich most of the time to lean for long periods of time. The tune is forced into open loop right now for what it's worth, but the O2 voltage should still be reading correctly.

I've had this problem for a long time and haven't been able to figure it out. It looks to me like the left bank isn't fueling properly. I've installed new coils, new spark plugs, larger injectors and a new fuel pump in the last 2 weeks.


edit: I forgot to mention that the WB is installed on the left bank.

[gottogo]

A simple test would be to swap the o2 sensors to see if the problem moves.

[csracing]

I've done that with no change in results. I also replaced the left bank O2 sensor with a brand new Motorcraft sensor.

[PST]

Exhaust leak on the left side? I've seen pinholes at welds do stuff like that to the o2 readings.

[reconscout]

If you are open to suggestions, maybe clean the connection from the harness to the sensor. I had a similar issue last week. Bought 2 new sensors, installed them. Still had a lean reading, low volts on one side. I thought, no problem I'll just switch the old sensor that I know was reading good from the other side in there. Started it up in front of my wife like I was going to be a genius that saved the world. But same issue. The next morning, I went back to it with a volt meter to check it all the connections out. I picked up one of the old sensors from the ground and was looking at the connectors, and looked in side before hooking it up and noticed a little bit of corrosion on them. I sprayed some electrical connector cleaner (I got before starting the work but hadn't used) in there on the harness side a few times. Hooked the same used sensor that was working well but on the other bank again. All of a sudden, the readings were working the way they should. Good luck. I was about to pull my fuel rails and clean all my injectors, lol.