P0131 and P0151 codes, why?

[danalihd]

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On the way to work this morning my truck was running kinda weak. I floored it from a dead stop and got it up to about 100 before letting off. It seemed to be holding back on me and I got the 2 above mentioned coded on the Predator. Any ideas? Incase I haven't mentioned it, I have a 6.0L with a whipple with stock pulley and a Nelson tune.

[farmtruc]

Did anything change, how about that smaller pulley.

The 131 is a oxygen sensor code. Low circuit on bank 1, sensor 1. How does the voltage look with the predator? During normal driving, the 02 voltage should go way up and then down, all over the place, if it is stable or lazy, you have a dying 02 sensor. At wot, it should be 900+mv.

the 151 is circuit low, bank 2 sensor 1. Same thing on this one. Looks like both front 02's didn't like something.

Let me know how those 02's look at wot.


allen

[Bandit]

Since both banks show a code, first thing is to verify them like Allen said by monitoring the O2's. If they are biased lean (stay under 450mv mor than going over) then look at fuel trims. If STFT or LTFT is adding tons of fuel, then check fuel delivery like a filter or pump.





Bandit!

[danalihd]

I had my wife watch the O2 sensors while i drove. The 2 in question never hit 900. I think the max was around 800. They were all over the place while driving. Also, the Ltrims did seem to lock at 0 at WOT, but, I also am gettin KR up to 4 at WOT. Nothing has changed, I don't understand it. It was running great. It's almost like the tune got lost somehow. This is all happening with the stock, 6lb pulley. I ditched the 8lb pulley for the time being. It has only been around 4000 miles since I changed the fuel filter and I'm getting great fuel pressure. at idle it is 52psi and at WOT it goes up to around 70. I did notice the other night that the spark dropped way down to 3 for a second at WOT.