The car has not been running right lately and I have a factory oxygen sensor that has 137k on it so im going to replace it.. I am also using shorty headers, I heard that if you have headers you need a "heated oxygen sensor". Is this true. If so were can I buy one and for how much?

Thanks

 

91Z28,

It sounds like you should have changed your O² about 100,000 miles ago.

A heated sensor can help maintain a good signal and sensor responsiveness on header installations, where the exhaust gas temperature can drop quickly after leaving the heads. Shorty headers are probably less prone to that phenomenon. I'd guess that you could get by with a standard, single wire O². They're about $25, whereas a heated sensor will be more like $55, and you'll need to change the factory wiring harness connector, add a relay, and add to the wiring harness. If you need to go with a three- or four-wire heated sensor, this type circuit should work well:

<h1>Four Wire</h1>


<h1>Three Wire</h1>

 

what is the purpose of a relay?

would it be okay not to use a relay?

I will probably get the 3-wire

hers a pic from sethirdgen.org

 

The circuit you show will work. However, the heater will remain energized at all times. The circuits above will shut down the heater whenever the O² is providing an acceptable signal toe the ECM. The ECM will enable the EVAP canister purge only if the O² is active. On long trips, the heater will be off most of the time. Once the ECM is on closed loop and the car is under almost any knid of moderate load, the heater will be off.

On newer vehicles, the PCM itself has dedicated outputs to control the heaters so that they only operate when necessary. The two relay circuits emulate that system on the "old" ECMs.

 

I just got an acdelco o2 sensor pn#asf-74 and it has 2 purple and one brown wire. How can I test to see if which wire is the positive,negative, and ecm wire.

Thanks

 

The two purple will be the heater, no polarity. The brown goes to the ECM O2 input.

RBob.

 

Thanks

 

If I get the four wire setup, how do I know which wire from the O2 does what?
What kind of relay should I use?

 

hi guys i am tryin to add a heated oxygen sensor to my 87 gta with flow tech headers they are semi shorties not the block huggers but not long tubes very hard to describ i dont kno wif you would still call them shorties anyway but never the less i wanted to know if you had to make those circuits above to tap into the evap canister power and still have it switched or if the ciruits were already there or if i can just hook the power wire to a 12v switched wire that goes to the evap canister that is already connected to a relay that will do all the work for me so i dont have to make any circuits and crap like that. and others hooked up their heated o2 sensors tot he fuel pump relay why would they do that the fuel pump never shuts off does it like you say the evap cansiter does right?

 

The A.I.R. pump solenoids would be a viable choice as well. No relays to add or anything, especially if you want to junk your air pump while you're at it.

"The air switching valve directs air to the exhaust ports during cold engine operation or anytime the fuel control system is in open - loop, and between converter beds during warm engine operation when the fuel control system is in closed - loop."

This is the one you want to tap into.

 

I've been putting together parts for this project whenever I get time. Where do you get a wiring harness to plug into your new multi-wired Oxygen sensor? I've been searching junkyards with no success. Would a dealer sell me this?

 

Homer, Scoggin Dickey has the connector for 22.44$
part 12126012.
About tapping in the air pump do you know in which wire to
tap to get to a 12 v power?
Ben

 

I forgot , part 12126012 is for a 3 wire connector.
Ben

 

I need to look in my shop manual again, but I believe wire "A" is 12V ignition. But it's hot the entire time the car is on. Wire "B" goes to ground and is switched by the ecm. That's why you'd need a relay if using a three wire unit. A four wire unit makes it easier. Connect one wire of the heater to A, the other to B, and the computer will complete the circuit on the ground side whenever the sensor cools off and goes unresponsive. The oxygen sensor lead goes to the ecm, and ground the other wire.

On my car (1988 Caprice 350 Carb) there are two identically shaped two pronged plugs. One white and one green. What I did is temporarily wire a light to each plug. The one you're looking for should light at idle, but turn off when you hit the gas. For my application, that's the white plug. It might not be the same color scheme for your car.

Scoggin Dickey's online catalog seems about worthless for finding these things. It lists them just by "connector." Did you get that part number from the paper catalog?

 

from: www.sethirdgen.org





Installing a 3-wire Heated Oxygen Sensor



This is primarily advisable if you have headers. Headers tend to cool the exhast gasses down, which in turn can affect Oxygen Sensor performance. To combat this, a self-heated sensor can be installed, to ensure proper operation regardless of exhaust temp, and also provide shorter times to closed loop operation. I will spare you the details on actually installing the sensor, since it doesn't take a brain surgeon, just a 7/8" wrench, sensor socket, or crowsfoot and some of your time.

The reason for this article is to explain how to properly wire it up. First, you will need the parts. I perfer to use AC Delco parts. The quality is unsurpassed. Also to ensure proper installation, and easy replacement in the future, it is reccomended that you purchase the "pigtail" or connector w/ leads, so that the sensor can easily be plugged and unplugged as needed.

The part numbers for these two items are:

3-wire Heated Oxygen Sensor: 25176708 GM List: $109.00

3-wire Weatherpack Connector: 12126012 GM
___________________________________________________-

I have ordered one myself.
Ben

 

According to my shop manual, "A" is the hot ignition wire, while "B" is the switched ground. A and B are labeled on the plugs.

 

anyone have part numbers for the four wire & the plug?
this sounds like a good way of doing it.. shouldn't draw too much even if I keep the air pump?

 

yeah 4 wire part number is 13444 can go into autozone and order an O2 sensor for a 97 trans am with O2 located behind the cat.. i checked on it for my install. i went with the 3 wire since it is 20 dollars cheaper.. i dont know about the plug though sorry. hope i helped a little

 

Thanks for your inquiry to www.gmpartsdirect.com.
Here are your part numbers you requested.


25312184 oxygen sensor x 4


That's all I got when I asked them for an oxygen sensor and plug for a 1996 Caprice 350. That's the part number for the sensor, still looking into the plug.

 

12102741 inline-to oxygen sensor connector (4-way female with leads) x 2

 

i also have headers, but can the one wire be used at all? or will it just mess the car up even more than not having them at all. my problem is my headers dont have O2 sensor holes, so my motor is running rich. im about to put the sensor in, but i wanted to know if i could put it further down the exhaust, like on my downpipe. i would like to know if i could use a one wire sensor that far down the exhaust, i dont care if i had to replace it every 3 months, cause i barely put 3500 miles a yr on my car.