05prerunner

I have searched this all morning with no luck but i finally bought a new Denso sensor from sparkplugs.com and it will be here sometime today. Ive asked this before but still not sure but my question is which wire from the factory harness matches up to which wire from the 02 sensor? Im assuming the Denso will have the factory wire colors but since i cut the harness off of the engine side i want to make sure i get it right. Can anybody tell me which colors from the tranny side match up to the sensor? I think i remember a red/white striped wire, a thick black wire, and dont remember the others but id greatly appreciate any help -- im only getting 15mpg at BEST with stock gears and 31's plus i drive 100+ miles per day so its killing my wallet

Elton

the new o2 sensor should come with a wiring guide

05prerunner

my el cheapo came with one too but it didnt match the color wires that were in the harness so if anybody knows i would sure appreciate it

05prerunner

and is Denso the exact same sensor id buy straight from the dealer?

05prerunner

well i got a test light and i think ive figured them out if somebody can verify it for me. Here's how its hooked up:

Denso Sensor wiring connecting to factory harness

BLUE -----RED/WHITE
WHITE----BLACK
BLACK-----BROWN
BLACK-----GREEN/WHITE


Bad part is my CEL light is STILL on seems to have a little more power and i pulled the code and got a 21 which is still the sensor i have an exhaust leak around the manifold flange but would that cause any lights? Im hoping somebody can please check the colors of their harness and let me know before i this truck

05prerunner

anybody??

InternetRoadkill

Your colors are different from mine. But here goes:

--- Colors on an 88-4R harness to O2 probe---
Black to Black (O2 sense output to ECU)
Brown/Blue to Grey (O2 ground)
Black/Yellow to White (heater sense to ECU)
Yellow/White to White (heater)

If either the heater or O2 sense is connected wrong, you'll get the CEL.

05prerunner

exhaust leak is very minimal now if not 100% gone, bought some exhaust repair stuff and let it sit overnight, even bought new battery terminals and upgraded some of the wiring to see if that would help but CEL still on. Havent gone but a mile or two and i dont think its true but somebody said you have to put quite a few miles for the ECM to relearn the new sensor? ive checked vacuum lines, leaks in the intake/exhuast and still no clue. guess ill save up and take it to a shop-- the check engine light really bugs me but i mainly want my MPG's back.

atatoy

I think you probably know this but here goes. The way to increased MPG is to keep of the gas pedal. I know your driving 100 miles a day but this does help. Always shift before 2500 RPMs. Try to use 1/4 pedal. If you can change to manual hubs and use synthetic fluids everywhere this will also help. Hpoe this helps.....out

05prerunner

ive got manual hubs and i rarely ever take the truck over 3000 rpms ever. i was getting at least 20 mpg when i bought the truck and now im only getting 15-16 at best. i try to barely keep any pressure on the pedal and think about where im shifting and 16 has been the most mpg ive seen no matter how diff. i try to drive. i give up for now but i have noticed that my manifold gasket looks like its peeling apart but doesnt seem to be leaking. cant tell if the manifold is cracked though. ill let you guys know if i get it figured out in case somebody else has the same problem. thanks again