91 Stang GT

so I was having problems with my o2 I thought I fixed it by patching 1 of the splice wires but the "check engine" came back on........I replaced with brand new o2 yesterday night and the same code came back on [91]......it only comes on while running???? need help getting real irritated?????

any input appreciated thanks in advance.........I believe this is the tech section correct me if im wrong

petrock

What trouble code are you getting? If [91] is supposed to be P0091, then its not an O2 sensor code. Its a fuel pressure regulator code.

91 Stang GT

yea it is a code [91] thanks petrock.......ill try that and see what happens ive already replaced the o2 with a new unit....im really getting frustrated.....uuuuughhhhhh!!!!!

91 Stang GT

ive replaced the fpr and still having issues.....light only comes on while driving and starts running like crap.......lean code [91] need help.........makes a whistiling noise and I don't kno where its coming from not sure if its the cai???I already replaced the o2 and fpr........plugged both [tad=tab] selenoids....don't kno where else to look....any input appreciated......really need help

Mike T

Check the pressure coming from the pump.

91 Stang GT

I guess I had bought a [4 wire o2 instead if 3 wire] swaped it out and pluged the tad and tab selenoids back in runs like a champ now......