Figured I'd share my research ansd R&R into 02 sensor replacement for the 93-95 (pre OBD II) trucks.
After my bonzai trip out east with my tandem axle trailer to pick up the back half of a Honda CRV in MD, my SC toasted the original 02 sensors climbing the hills of WV. Bad idle, total crap gas mileage, and stumbling under tip in throttle were the symptoms. BTW, no ck engine light for this. I attributed this to them being 'in range" just slow.
After a lot of research into my options, I decided to try the new Planer style O2 (vs thimble type original) introduced by bosch circa 1998. Basically, the difference is that the thimble style uses slots up the side of the probe to sample, the Planer style has the sampling at the very tip. The protection from contaminants is better with the Planer style, and it is considered to be longer life than the thimble style as well. IMPORTANT NOTE: The Planer style 02 also uses a different resistance heater circuit, which is known to trigger 02 Heater Circuit codes in the OBD II cars and trucks, btdt and also noted btdt on this list. That said, Planer Style works on pre OBD II cars and trucks, because OBD I does not have a feedback loop for the heater circuit. NOTE: Planer Style 02 Sensors can be used interchangeably with thimble type on pre OBDII trucks (specific to the 1FZFE 93-95 all)
Ok, back to the install. First, get heat! The 129k/12yo 10mm nuts on the 02 studs were just about gone on my truck. I heated the nuts up red hot (using a tethered style propane gun), then started backing them off with a pair of pliers, finishing with whatever size ratchet box fit (9-11mm in my case). Second, make sure you have new replacement nuts (they don't come with the sensor), you will be glad you did. I didn't, but used some exhaust type copper nuts I had in the shop. Do NOT use steel for these, unless you are never going to go back at this project again.
Outbound O2. There is a protective heat and crud shield for the outbound 02 sensor. I used pliers and bent back the shield to get access to the outer flange nut. Heat and remove nut. Then used pliers to pivot the shield to get access to the other flange nut. Heat and remove. This gives you a slightly mangled heat shield, but I used pliers to put it back to a protective shape and reused.
Inbound 02. Pretty straight forward since there is no shield on it. Again, heat the nut to red hot, and wrestle out. I suggest the rear nut first, as it's one that requires some contortion around the control arm and body mount. Be careful with the heat on this sensor, the water lines for the rear heater (inspect heater hose and clamps while you are there).
Cut and splice 02. I used Bosch application 15728 universal, which I believe is the 4 wire for the 3FE engine, but it is a direct replacement fit for the 1FZFE. You get a flange gasket, as well as, Bosch's new weathertite connector setup, which IMO/E is one of the best splice setups I've ever worked with. I believe Autozone has the best retail on them at ~60each. Note: 1FZFE sensors have a left and right, in universal applications, just get 2 of either one.
O2 wire Color Code Mr. T - OE
Blue = Signal wire
White = Heater wire 1 (non polarity)
Brown = Heater wire 2 (non polarity)
Grey = Aux Ground
O2 wire Color Codes: Bosch 4 wire sensors use the following code:
Black = signal wire
White = heater wire (non polarity)
White = heater wire 2 (non polarity)
Grey = Aux Ground
Ok, the obvious (T = toyota B = Bosch):
T - Blue > B- Black (MOST IMPORTANT)
T - White > B - White
T- Brown > B- White
T - Grey > B - Grey
About the only thing tricky about the connectors (other than large hands need not apply, er that's me) is that you make sure the wires are oriented to the plugs. I'll post some pics if this gets to the FAQ stage.
I added about 6in to each 02 harness length, so that I had room to put the splice connector somewhere out of the way. Clean off the flanges for the 02's with a small wire brush. Reinstall new gaskets and 02's, string the harnesses, and make sure you tether the outbound harness to the chassis, as the exhaust is right there. Don't forget to put back the heat shield on the outbound 02
Remove 15 amp EFI fuse to reset the computer. This allows the FTU to relearn the fueling needs of your truck after the 02 install.
Right off the bat, my stumbling problems went away, the idle is smoother, and the less that WOT behavior is much better. Here's hoping the gas mileage increase is massive (good luck with that supercharger boy,
)
About 4 banana ( and dirty job) ~ 2hours realistic install time
HTH
ST
94 FZJ 80 Supercharged (new Bosch 15728 x 2)
After my bonzai trip out east with my tandem axle trailer to pick up the back half of a Honda CRV in MD, my SC toasted the original 02 sensors climbing the hills of WV. Bad idle, total crap gas mileage, and stumbling under tip in throttle were the symptoms. BTW, no ck engine light for this. I attributed this to them being 'in range" just slow.
After a lot of research into my options, I decided to try the new Planer style O2 (vs thimble type original) introduced by bosch circa 1998. Basically, the difference is that the thimble style uses slots up the side of the probe to sample, the Planer style has the sampling at the very tip. The protection from contaminants is better with the Planer style, and it is considered to be longer life than the thimble style as well. IMPORTANT NOTE: The Planer style 02 also uses a different resistance heater circuit, which is known to trigger 02 Heater Circuit codes in the OBD II cars and trucks, btdt and also noted btdt on this list. That said, Planer Style works on pre OBD II cars and trucks, because OBD I does not have a feedback loop for the heater circuit. NOTE: Planer Style 02 Sensors can be used interchangeably with thimble type on pre OBDII trucks (specific to the 1FZFE 93-95 all)
Ok, back to the install. First, get heat! The 129k/12yo 10mm nuts on the 02 studs were just about gone on my truck. I heated the nuts up red hot (using a tethered style propane gun), then started backing them off with a pair of pliers, finishing with whatever size ratchet box fit (9-11mm in my case). Second, make sure you have new replacement nuts (they don't come with the sensor), you will be glad you did. I didn't, but used some exhaust type copper nuts I had in the shop. Do NOT use steel for these, unless you are never going to go back at this project again.
Outbound O2. There is a protective heat and crud shield for the outbound 02 sensor. I used pliers and bent back the shield to get access to the outer flange nut. Heat and remove nut. Then used pliers to pivot the shield to get access to the other flange nut. Heat and remove. This gives you a slightly mangled heat shield, but I used pliers to put it back to a protective shape and reused.
Inbound 02. Pretty straight forward since there is no shield on it. Again, heat the nut to red hot, and wrestle out. I suggest the rear nut first, as it's one that requires some contortion around the control arm and body mount. Be careful with the heat on this sensor, the water lines for the rear heater (inspect heater hose and clamps while you are there).
Cut and splice 02. I used Bosch application 15728 universal, which I believe is the 4 wire for the 3FE engine, but it is a direct replacement fit for the 1FZFE. You get a flange gasket, as well as, Bosch's new weathertite connector setup, which IMO/E is one of the best splice setups I've ever worked with. I believe Autozone has the best retail on them at ~60each. Note: 1FZFE sensors have a left and right, in universal applications, just get 2 of either one.
O2 wire Color Code Mr. T - OE
Blue = Signal wire
White = Heater wire 1 (non polarity)
Brown = Heater wire 2 (non polarity)
Grey = Aux Ground
O2 wire Color Codes: Bosch 4 wire sensors use the following code:
Black = signal wire
White = heater wire (non polarity)
White = heater wire 2 (non polarity)
Grey = Aux Ground
Ok, the obvious (T = toyota B = Bosch):
T - Blue > B- Black (MOST IMPORTANT)
T - White > B - White
T- Brown > B- White
T - Grey > B - Grey
About the only thing tricky about the connectors (other than large hands need not apply, er that's me) is that you make sure the wires are oriented to the plugs. I'll post some pics if this gets to the FAQ stage.
I added about 6in to each 02 harness length, so that I had room to put the splice connector somewhere out of the way. Clean off the flanges for the 02's with a small wire brush. Reinstall new gaskets and 02's, string the harnesses, and make sure you tether the outbound harness to the chassis, as the exhaust is right there. Don't forget to put back the heat shield on the outbound 02
Remove 15 amp EFI fuse to reset the computer. This allows the FTU to relearn the fueling needs of your truck after the 02 install.
Right off the bat, my stumbling problems went away, the idle is smoother, and the less that WOT behavior is much better. Here's hoping the gas mileage increase is massive (good luck with that supercharger boy,
)About 4 banana ( and dirty job) ~ 2hours realistic install time
HTH
ST
94 FZJ 80 Supercharged (new Bosch 15728 x 2)
In my case, just the fact my 02 sensors lasted 125k is fine with me (almost 20k with the SC). However, they certainly could have lasted longer without forced induction. Rick, the reason all factory turbo and SC applications use a different 02 than a normally aspirated engine is exactly that forced induction requires better ceramic protection and lower (less exposed) sampling profile. The Planer style 02 should reduce that known issue significantly.
