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Ok, I've took some readings on my O2 sensors because I believe that's what's causing my long term fuel trims to be around -23% during idle. I read up on O2 sensors and all that stuff and found that the voltages should look like a radio wave and be between a set value.

The link below to an excel spreadsheet are my readings. The columns highlighted in yellow show problems.

If you look at it, B1S2 and B2S2 voltages are both steady, not ocillating like a radio wave (B1S2 staying at .8 roughly and B2S2 down near .1) The fuel trims for both also show 99.06%. Then you see my LTFT at about -24% while idling.

If I'm driving, my LTFT goes close to 0 (+-4%) but when at idle, they go back down. I didn't get a chance to read the o2 outputs while driving.

So correct me if I'm wrong, but I'm thinking my B1S2 and B2S2 o2 sensors are bad and need replaced. This would explain the engine running rich (with the stock airbox on, the engine runs lean (+11-14% LTFT) with the CPE Mafci, it runs rich).

Secondly, where are these located, does anyone have a diagram of the 2 sensor locations? B1S2 means Bank 1, Side 2 and B2S2 is Bank 2, Side 2. So, are these both after the cat, or one before the cat, and one after the cat? I know there are 2 up on the engine and then I know of at least one more after the cat, I'm not sure if there's a 4th.

Any help or diagrams of locations, anything would help.

Link to the file:
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