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Discussion Starter · #1 ·
Hello all,

I’ve just purchased a 2007 rubicon that has a 2014 5.7 motor. I got it for a screaming deal because it needed a cam and lifters and o2 sensors (or so I thought) . It ran and idled and everything before I tore into it but it did have wild b1 ltft and trouble codes for the rear o2s. I recently did a cam upgrade and I’m trying to tune it but I still have 3 trouble codes for my o2 sensors and my LTFT on bank 1 are so rich (-25 to -30) while bank 2 will be +/- 3.It pops and bangs because of the raw fuel igniting in the exhaust. I have checked for vac leaks and there are none. I really just need some second opinions or if there are any other test I should be doing before I pull the trigger on another PCM.
Both front o2 sensors respond on a graph similar to each other but b1 is very very very rich. Verified by spark plugs and both o2 sensors on driver side are significantly darker than the passenger side. I have already replaced the b1 sensor and it did not fix the issue and that’s why I started testing everything. TIA
P0031 - HO2S Heater Control Circuit Low (Bank 1, Sensor 1) (SES, Current)
P0138 - 02 Circuit High Voltage (Bank 1, Sensor 2) (Pending)
P0158 - 02 Circuit High Voltage (Bank 2, Sensor 2) (Pending)

I have recently unplugged the pcm and o2 sensor harnesses and checked resistance of all wires related to the oxygen sensor system and everything checked out flawlessly with 0.0 ohms on every single wire. The grounds all check out to engine ground with 0 ohms. I have tested the o2 sensors with a multimeter and they all check out as well. (8 ohms across the heater element)
After that I did key on voltage for the heater circuits and sensor wires.
B1S1 tested as follows
Red: 2.5V
Orange: 4.25V
Brown: 2.7mV
Black: 2.5ohm to engine ground with key on

Green: 2.5V
Grey: 4.25V
Violet: 2.5mV
Black: 2.5 ohm to engine ground with key on

Red: 2.5V
Yellow: 4.25V
Tan: 2.9 mV
Black: 2.5 Ohm to engine ground w key on

Green: 2.5V
Pink: 4.25V
Grey: 2.5mV
Black: 2.5 ohm to engine ground w key on
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