junglejuice - your best best is Inject A Carb (do a google search). they are in Oz and if i remember ship for free. $75/o2. ive seen a lot of folks have probs with bosch repco units so avoid that - plus they cost more. you should have one o2 with 4 wires in front of the cat (which is the main short fuel trim sensor OR the o2 that the pcm relies on MOST for correct injector flow/on time) and one behind the cat (also 4 wires) which monitors the cat's performance but also contributes to long fuel trim which is data collected by the pcm to set its own parameters over several weeks or longer. this sensor can affect fuel consumption to a lesser degree. the point is, the second o2 does have an impact on fuel economy and performance, but nothing like the upstream unit. bottom line, replace both or at least the upstream unit if you are on a budget. ive also found (and now regularly use) Denso o2s from ebay for half the price but you must configure the wiring and connector yourself so involves a lot of research and fiddling. here is some info for wiring of o2s although u must sometimes decipher your own wrigs wiring yourself:
MAJOR BRAND OXYGEN SENSOR WIRE CODING:
SIGNAL GROUND HEATER HEATER
AC DELCOPURPLE TAN BROWN BROWN
BOSCH BLACK GREY WHITE WHITE
BWD BLACK GREY WHITE WHITE
DELPHI PURPLE TAN BROWN BROWN
DENSO BLUE WHITE BLACK BLACK
NTK BLACK GREY WHITE WHITE
SMP/STD BLACK GREY WHITE WHITE
i cant remember if the inject a carb universal 4 wire units (the one u should order when u look on their website) have connectors but most factory jeep o2s will match the bosch color coding (between the o2 and its connector)..this is only a rule of thumb so dont rely 100% on that...heater circuits can be cross wired without problem (like a light bulb) so dont sweat the two same-coloured wires...cut the stock connector off the old o2, wire it up according the chart above and use it with the new one! simple as that (hopefully)
