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ok need some help on this one. My short term fuel trims are swinging way high and then to zero then right back up again over and over. This happens at part throttle cursing. At idle they are pretty steady but one side stays high. What would cause this. Ive posted a screen shot of the scan where they are bouncing up and down. vehicle has headers and no cats. and a cold air intake. wide band is also showing it running pretty lean. engine runs smooth and drives ok
Do you have datalogs of the vehicle when it was totally stock? Did you scale the MAF sensor?
I think the fuel trims are a result of the O2 sensor readings. This could be caused by an exhaust leak or other mechanical issue. Or a bad sensor(s)
What happens if you remove the O2 sensors? Start with the bank that is reading lean.
BTW -- I understand the "part throttle cursing" -- I've done that myself :)
I still need to scale the maf. But didn't want to start changing things if there were other problems. I did scan it when it was stock I don't have that scan anymore. I noticed the biggest difference after the cold air intake. I just didn't think it would effect it that much.
I would scale the MAF at this point or put the previous intake back in.