shum8

Im headed to parts store for an O2 sensor. Do i buy a universal or one specific for my vehicle? Its an 88 with a 4.0. I cant find the 3 wire plug that was on the factory O2 sensor. Any help would be greatly appreciated. Thanks

DFlintstone

BOSCH # 12009, NTK #23553, Denso #2343116 I went with the NTK, seems fine.

Yes, they are specific for 87-90 Jeeps!

DFlintstone

That plug, the knock sensor, and the CTS wires all come up and tie in to the harness for the injectors near the front IIRC.
I linked below my "foray" into the 02 sensor. You will be looking for a ground, a 5v feed from the puter', and a 12 volt for the 02's heater.

https://www.cherokeeforum.com/f2/ren...ce-rms-133153/

shum8

Ok when i bought the 88 all these wire were just hanging. There is a bare wire that runs in loom with O2 plug. What is this? I went ahead and ordered a Bosch O2 Sensor. Im having someone pick it up so Ill have it when I get up around noon. Im more excited about this thing than my son is.

DFlintstone

Bare? Sounds like maybe it cooked. You might look at EcoMikes link in my link above, since that's where I got allot of info. In my signature link there is a diagram showing the relays, one is for the 02 heater...maybe the cooked wire? (that is the only one at 12v carrying much power.) Then like I mentioned, then there is a 5v feed from your ECU, and a ground that should have an ohm or so, or less, resistance to battery negative.

That bare wire...Keep in mind that when a wire shorts it can cut right through the insulation of the wires with it....and connect them! Your coolant temp sensor down there is pretty important as well.

Btw, I jacked my jeep by the frame so the axle was hanging, and removed the left front tire to reach in there. You can chop the wires on the 02 to get a 7/8 box wrench on it. It might not be hard to remove....Oh...if you had wires!

tjwalker

Never install a universal oxygen sensor; no lack of problems with them. Always buy engine management sensors that are specific to the vehicle.

For the 87-90, Bosch is fine and actually is the OEM sensor off the factory line. After 90 though, from 91-01, Jeep used NTK sensors so I highly recommend them for these years. Both brands are widely available and not that expensive.

Be darn sure all wiring and connectors are in good shape!

shum8

So I read the link. Made my head hurt. Should I check out the plug in before I install new O2 sensor? Seriously...am I gonna be able to tell when I get her installed?

DFlintstone

Yea! Sorry. Could have done without Rrich's help there. Assuming you found your plug...yea the 02 controls the final fuel trim, matters to me! Mike's link might be easier to follow.

You found the Jeep side plug? Maybe you're fine....do you have a meter?

I had thought you were missing the Jeep side connector. Anyway I looked. Black is ground, Orange is the 02 heater, (best to check that for 12V with it running), and the grey is the 5V feed from the ECU. The colors on the pig-tale of the new sensor might not match, that's OK.

These three wire 02 sensors, for 87-89 are different. It seems "Titania" 02 sensors work like a variable resistor to ground, (for that 5 volt ECU feed). The 4 wire (Zirconia) in 91 on are completely different. (Thank Hank!)

shum8

I have an analog meter. Ive got to investigate that bare wire also.

DFlintstone

Analogue will be OK for that...if you do decide to check. about running voltage.....about 5 Volts. Grounds are grounds.

I think the CTS has two wires, Guessing the knock sensor also has two. Are they hooked up OK? I'm wondering what the bare wire is for, and what it might have burned into.

DFlintstone

Head spinnen? Get this. One diagram shows a ground from the injectors on some sort of shield around the knock sensor wires. (your misery wire?) Black it says. Then the Knock sensor, Violet/white, and yellow black, then the coolant Temp sensor Tan, with the Brown/white stripe ground.

Someone should ask Cruiser about a shield on the knock sensor wires with an injector ground there.....

shum8

They are all very oily. The wire loom on the whole vehicle is crap, So its missing from O2 sensor plug about halfway up engine. Ima have to investigate all this tomorrow. Thanks guys for the help. Lots of issues have been resolved just of off info Ive goten on this forum. Thanks

shum8

kinda hard to tell but the wire to the right is completely bare. Im unsure exactly where it goes. The loom is rotten and gonna have to be dealt with all the way to the fuel rail. Gonna tackle that now. I did see some shileding tho inside the loom near the rail

shum8

shum8

So that is what I have. I know what the O2 sensor plug is but as far as the other 2 I have no idea. The bare wire does go inside the shielding. Both fittings are broken. But they were fastened decent. Can u buy these and splice them?