1 wire O2 conversion

[silent hill 3]

so the OBD-II is not compatible right because of heater curcuits. well this is my problem,(3-wire sensor only) my cars harness connector is messed up so what i was going to do is cut the connector off of the O2 and the cars harness connector, then splice the three wires from O2 into the three wires of the cars harness. i guess its not really a 1 wire conversion and you'd still have the same thing as you would with out cutting and splicing but, ive been thinking of doing this for a while. anyone think it will work.


HOLLA BACK

[RigsPGT]

I bought the sensor from Autozone ($26.XX) but its late now, i just have to wait for tomorrow and test the results. Past couple of fill ups ive been getting shitty mileage, around 230-270 miles instead of the 325 minimum driving city and highway.

[RigsPGT]

Well, i changed the sensor, cut the 3 wires (2 white +1 grey) and hooked the black one there with the new sensor. Now my question is this :

Could someone verify the right color for the PCME wire? Is it the black wire or the grey one? If its the grey one, im screwed, have to redo it again. As far as CEL, i get EGR code all the time so without checking the codes again i cant tell if the sensor is working with the black wire or not.

Looking my front and rear sensors they were kinda white or yellow-white, LEAN condition

[steeb]

Originally posted by Zoso142
The main reason Autozone asks you what car is it from is because Bosch O2 sensors have a 3 month warranty and they want to record it in their system for your benefit. Eventhough you hack it up and put it on the wrong car.

Worked there for 2 years.

stuff needs to be hacked to fit these? i thought they were universal

[Omaha95PGT]

I did a how-to re-write below:

Single wire O2 sensor conversion originally conceived by ryanpzz, original pics by waderpgt modified by Omaha95PGT.

The single wire O2 conversion requires that you hack the old O2 sensor wires (it's a 4 wire). Do not hack the car's wiring harness. Just cut the wires at the base of the O2 sensor so you have 4 pigtails to work with. The old O2 sensor's 4 wire harness will still be plugged in but you just have to use 1 wire out of the 4. The other 3 should be insulated such that they do not contact anything (grounds, etc.). waderpgt recommended silicone tape, but paint on insulator or heat shrink tubing can also be used. Be sure to reuse the insulator sleeve that was originally on the old O2 sensor.

Some pics:

Bosch 11027 on the right and an old O2 sensor on the left
Bosch 11027 on the left and an old cut O2 sensor harness on the right

To review, you will be using the “universal” O2 sensor (no harness) version of the 1984 Chevy Caprice with the 3.8L V6 engine. The Bosch equivalent is the Bosch 11027 O2 sensor. Although there is a crimp connector on the universal O2 sensor, I’d recommend crimping then soldering the wires together in order to ensure a good contact.

The only difference between the single wire O2 sensor and the 4 wire O2 sensor is the loss of the ground wire (usually gray), and the 2 heater wires (usually white). The black wire is the sense wire. Functionally, the single wire O2 sensor should work exactly like a 4 wire O2 sensor except that the O2 sensor heater is gone which means that the O2 sensor will take a little bit longer to reach operating temperature. So instead of 30 seconds, it might take 2 minutes (n.b. arbitrary numbers) which means that the car will be running a bit rich a little longer until the O2 sensors heat up. If I understand correctly, the change to the 4 wire O2 sensor was done to reduce start up emissions.

Also, this conversion pertains to OBD-I cars (’93-’95 V6 KL engines). OBD-II cars look for the O2 sensor heater circuits to be intact. Since the conversion has none, it will return a CEL. You may have an option of splicing in a universal 3-wire O2 sensor which is a bit more expensive but still cheaper than a dedicated OEM type O2 sensor

To do a 3 wire conversion, hook up the 2 white wires to the heater circuit on the new universal O2 sensor. IMO, I would not do a 1 wire conversion b/c of the lack of the heater circuit. A 4 wire universal would be the best since it provides the O2 sensor with a dedicated ground and it would return a more consistent voltage. IMO, I think a 3 wire conversion would be serviceable and not pose any problems.

[Gro Harlem]

Holy craaap! you guys kick ass! I am definitely going to try this with my MX3. I've been getting erratic idle and my fuel economy has been going to shit lately, and I suspect its my 140k old O2 sensors.

I am going to do this on my MX3. I think the wire colors are similar if not the same so we'll see.

[Gro Harlem]

BTW: Advance auto parts charges $69.99 for universal 4-wire (w/heated element) O2 sensors and $288.88 for the OEM replacement for the MX3's....2 are required!! SCREW THAT



The 11027 is only $17.99 each from the same store.

[Omaha95PGT]

Has anyone found out if the OBD-II resistor trick actually worked? I'd think that the resistor would overheat and fail over time. Is the heater circuit always on or is it timed?

$288.88...geez

[TakimanPGT]

I suggest that you guys buy the sensors conditional on the store having some kind of limited guarantee on the sensors. Do NOT tell them that it is being used on a Probe.

I know
a) Autozone has some kind of 3 month warranty on these sensors. Check with your local store to make sure you get the warranty.
b) Advanced Auto has a 1 year limited warranty on the same sensors and is easier to deal with w.r.t exchanges/claims.

I have already gone through 4 of these sensors now in less than 4 thousand miles tops. First set was from Autozone and I guess they forgot to record my warranty PLUS it was already beyond expiration so I had to buy the second set. Out of the second set, one sensor is still erring giving me codes. (For the second set, I bought one at each store due to lack of stock). I exchanged that one at Advanced Auto, no problems. With everything taped carefully and general wiring given a look-over (it's bloody cold to look any more carefully), I still have errors popping out of nowhere. I don't have problems at the ECU because I connected my old 4-wire sensors (which hadn't thrown a code when replaced) nor in the wiring leading upto the connector. I keep getting both codes meaning inversion and inactivation on both sensors. And this happens intermittently be it city/highway driving. And only when single wire sensors are used. I don't have access to any more investigation tools so if someone has suggestions, I would love to use their help.

[Omaha95PGT]

So who else who has already done the single wire O2 conversion had similar problems? It would be good to log successes and failures which would also help determine possible problems with installation and ways such problems can be fixed.

The only things that I can think of for you, TakimanPGT, is either failure/corrosion of the electrical connection at the crimp or a poor ground to the sensor.

You can test the former by using one of those press on electrical taps (much like the ones for the fog light mod) on the sensor side of the crimp. Using your multimeter set on resistance (Ohm) test the resistance of the wire from the tap to the corresponding wiring harness pin. The resistance should be very low. One way to help avoid a bad connection would be to flow some solder to ensure a good connection and then use some heat shrink tubing on top of that to protect the connection.

With regards to the ground, you can run an extra grounding wire to both heads. Prior to doing that, check the resistance of the ground by touching the negative battery terminal and then touching the body of the O2 sensor. If you have a set of jumper cables, attach one end of the cable to the negative terminal and the other to a good grounding point on the head such as the engine lift or, just for testing purposes, the heat shield on the exhaust manifold.

TakimanPGT, which sensor is going bad on you? Front, Rear or both?

[TakimanPGT]

Originally posted by Omaha95PGT
TakimanPGT, which sensor is going bad on you? Front, Rear or both?

Both the first time around. I ran up codes 15, 17, 23, 24. Second time, I had 15 and 17. I have cleaned the connectors with some of that STP electrical cleaner. And I don't have access to a soldering gun but have used crimp connectors and an ungodly good amount of electrical tape. I'll try running an extra ground wire from the sensor to the heads.

Right now, I don't have any codes. And I haven't driven the car for more than 3 miles anyway. The codes turn up after a while of driving and so, I really won't know until I drive it around.

[olson2cm]

Originally posted by Omaha95PGT
Has anyone found out if the OBD-II resistor trick actually worked? I'd think that the resistor would overheat and fail over time. Is the heater circuit always on or is it timed?

$288.88...geez

Marc, looking at the wiring diagram in my haynes manual, I don't see anywhere in the heater circuit that leads back to the PCM or whatnot... It appears to just be a 12v and ground (low amp) circuit that would continuously heat the sensor.

With that said, I'm sure there is a way to trick the system. The trouble lies in making it reliable over the extended time that a sensor should be in service. Once all is said and done, I think it wouldn't be as viable as just getting a 3-wire universal for ~$50. This isn't too bad to chew since it appears that our lower o2 sensors (Which are 4 wire and REALLY expensive) don't do a single thing performance wise so we shouldn't even bother replacing them. I can deal with $100 to replace 2 o2 sensors, but not $600 for 4

[PA_Probe]

Just picked up my Bosch 11027 sensors at Advance.
I plan to do this on the weekend. I will post how it goes.
Currently i was getting codes 15 and 24.

[shaodome]

Another satisfied customer....No Cel!!! Thanks for thinking of this and saving everybody $.

[PA_Probe]

Did the conversion this weekend. No CEL from the first start up. Just filled up with gas so i will post my gas mileage with these sensors. on saving money.