schardbody

i pulled a code 48 my 92 VX, so it looks like im going to be needing a new O2. anybody know of somewhere that sells them thats isnt $300. is there an alternative to using these expensive o2s??? im getting about 28MPG all highway driving which sucks for a VX, only things done to it, are 94 VX engine swap, short ram intake, catback, that shouldnt be causing the problem should it??