Have an 03 mach 1 I am working on. It runs very well under heavy throttle situations. At idle and partial throttles under certain loads it has a misfire. Has thrown codes for P1131 (lean on bank 1) and P1151 (rich on bank 2). Also, per the picture below, fuel trims as well as o2 sensor output appear to be almost opposite each other. Low voltage on bank 1 to command more fuel, and high voltage on bank 2 to reduce fuel.
The internet tells me these codes can often mean a vac leak, but i have sprayed the entire engine down with carb clean while running and no change in idle. Also, one would assume a vac leak would cause both sides to be lean. I noticed both o2 sensors appear to be NTK, which are not factory and may be newish? I may swap the bank 2 one with the bank 1 and vice versa and see if problem follows. Any other tips? Injector problem? Am i being naive and should just replace both o2 sensors? Trying to do a little diagnosis before being lazy throwing parts at it haha.
The internet tells me these codes can often mean a vac leak, but i have sprayed the entire engine down with carb clean while running and no change in idle. Also, one would assume a vac leak would cause both sides to be lean. I noticed both o2 sensors appear to be NTK, which are not factory and may be newish? I may swap the bank 2 one with the bank 1 and vice versa and see if problem follows. Any other tips? Injector problem? Am i being naive and should just replace both o2 sensors? Trying to do a little diagnosis before being lazy throwing parts at it haha.
