I have a 1985 firebird with a brand new GM 350 engine, shorty headers, and the stock quadrajet carburetor. All of the EGR stuff has been removed, except the charcoal canister. I have been thinking about my oxygen sensor, and whether it's worth replacing. I currently am set up for the one wire sensor. One wire sensor-20 bucks. 3 wire heated o2 sensor- 50+ bucks ,(90 bucks for a nice looking wire and connector setup for the one-three wire conversion) I have heard the headers do not keep the sensor hot enough to send a proper signal.
Also, do the sensors ground themselves through the threads? Would i ever have to worry about a bad ground when running headers?

My main concern is whether the oxygen sensor is worth replacing, and if so, is it worth getting the three wire conversion?

 

I prefer the heated 02s. I had a new o2 in my '88 iroc w/ hooker shorties normally getting 17-18 mpg then added the heated o2 design and the mileage did actually go up a bit the best I recall was 19mpg that's city/hey mixed...... 5.7 T-5 and 3.27 gears and 245/50/16s the car idled much smoother. was very happy with that car til it got hit

 

Not a problem with shorties.
Problem arises with long tube headers that have sensor mounted at collector end ;
the sensor is too far back from the exhaust port and cools off when the car idles putting the engine back to open loop tune

They don't last forever so a new one ( of your choice ) is a good investment

 

That would definitely make sense. The oxygen sensor is only like 3 inches further from the exhaust port. I can't imagine the temperature difference being too great. Long tubes would put the sensor pretty far away. Well thank you for your response, I would hate to waste the money on a heated sensor at this point when a one wire sensor is less than half the price.

 

I have read that it will speed up how long it takes to heat up the sensor. I know I have to wait at least 5 minutes to get my sensor hot enough. It runs kinda weird (some hesitation) when cold. Is there a conversion kit or something like that for this? I wanted to get a 3-wire but saw that the connector was different.

 

Depends how pedantic you want to be.
3 wire (heated ) O2 has a power wire and a ground; as well as the sensor wire.
All you have to do is supply a switched 12V to the heater , a ground somewhere and reconnect the O2 sensor wire using connectors

If you want it to look like stock then need something like this
http://tpiparts.net/inc/sdetail/2167
http://tpiparts.net/inc/sdetail/15837

 

Hmmmm...that's kind of pricey for what it is. I guess all you have to do really then is just cut off the connector and route each wire yourself if you don't want to pay the extra $26 for the adapter.

 

Some inline crimps and stock style corrugated sleeving would take care of the cosmetic side of things; not as if you are going to be disconnecting it every weekend

 

That's what I was thinking. I'd cut off the plug from the sensor I have now, solder that on to the new one, put heat shrink tube around it. Then I'd just ground one wire to the body and find a key-on hot wire somewhere.

 

Heater element draws a bit of current so Hi amp supply like fuel pump relay is popular source

 

Excellent, I'm pretty excited to try this.

 

Alright, this is probably going to sound pretty dumb, but how would I wire this to the relay?

 

One heater wire to the switched side of relay. ( other to ground ) .
When relay operates it sends power to fuel pump and to O2 sensor heating element

Typical GM pump relay wiring shown below
( confirm your actual configuration here
http://www.austinthirdgen.org/index.php?pid=19 )

Need to connect to terminal A on relay ,
might even consider installing a in-line fuse so you don't take out the main pump supply fuse. Engine will run without the heated sensor ; it won't if the pump won't run

 

Okay that seems simple enough. How do I determine what size fuse to use?

 

This is an old post and doing some research ran into it.
Question on the 3 wire O2.
I want to install O2's on both sides so I can periodically check how the other bank is doing.
Will the heated O2 keep it clean while it is not being connected to the computer. I imagine the O2 doesn't know if it is connected or not so I can't imagine it matters.
Thanks
Don

 

well let me input my 2 cents. for one the heated 02 sensors do NOT DRAW A LOT OF POWER. and do not need a relay by themselves. they are low amperage. shorty headers are a thinner metal and dissapate heat a lot quicker than cast manifold. period! you can and will get an intermittant ses with shorties and a regular 02 sensor. and if you have a full flow exhaust with no emissions it will be sooner. rather be shorties or long tubes. a heated oxygen sensor heats faster and stays the same temp longer if not all the time. they work great. the one i used actually had 4 wires. 2 were ground, one hot and one ecm.


if you put one in on the other side the ecm would not know the difference unless they gave too many different readings which might throw an ses. but if you put onother one in and hooked to an air fuel ratio gauge it would not know the difference.


this is the one i am using.
http://www.summitracing.com/parts/CEI-103025/

 

^^^^what he said.. headers give off heat, plus better flowing exhaust system and if you have a cam the overlap of air and unburned fuel cool down the exhaust. I was surprised how not so hot the exhaust is from the tail pipe. If thats not hot then the headers are not near 600+ degrees which they say is needed for the O2 to be fully functional.

They also don't pull crazy power like one92rs said..
I measured a 3 wire and 4 wire... the 3 wire pulled .600ma cool, as it warmed it dropped to .500ma the 4 wire pulled a little more close to 1A but it also heated up a little faster probably because they are used with OBDII which has tighter emissions. Also look at the factory wiring at cars with heated sensors its 18GA wire.. an inline fuse maybe 5A will be fine.

I did the mod a few weeks ago. it was a little bit of a pain running the wires for 12V and ground because the shorty headers are in the way and I don't want heat to damage the wires.. If I were to do it again I would do a 4 wire since your already under there running wires..
I got a three wire sensor and connector pigtail for the car side from rockauto, I spent less than $60 and it looks like factory.. well worth it since I swaped to a 95 truck pcm and they come with a 3 wire O2.

Its a nice change to see the O2 working on my af gauge when the car is luke warm a few minutes after startup and idle is a tad less rich and a bit more steady. Sorry for the long post but wanted to cover a few things.

 

More concerned with the O2 not reading correctly.
My car has long tube headers
Ignore the O2 with the purple wire. That is the one I have been using

With a multiport system, totally non stock.
I just want to make sure the O2 I am not using will function when I need it if I use the 3 wire system

On another Triumph I am building with TBI. Is there a problem if you run 3 wire O2's too close to the manifold?

 

in the picture it looks like the o2 sensor is in one of the primary tubes? wouldn't that hurt some of the flow through that exhaust port?

a 3 wire will work fine down further.. you can screw both in and heat both of them I don't see why that wouldn't work.. they will both wear out eventually connected to the computer or not.

 

Are you talking about the one at the top or the ones downstream at the end?

 

sorry.. the one at the top.

 

That's why I plan on changing to the ones on the bottom.
I wish there was a way for the OBD 1 ecm to read both O2's

 

I just ordered this heated 4 wire o2 from Summit. http://www.summitracing.com/parts/CEI-103025/?rtype=10 . I just want to confirm the wiring before it gets here. My only question is the 12 volt power supply feeding the o2. I see alot of ppl saying to grab switched 12v from the fuel pump relay. So I should just T wire in the O2 wire with the Tan/white tracer(A terminal on the Fuel pump relay)?????

 

I wouldn't splice into an important wire in the system like the fuel pump.. but thats just me. I probably would have run a wire to the fuse panel, they even sell those add a fuse taps. I got lucky, I don't use the ESC module under the hood so I had a power wire available... If your not using the EGR valve thats a power source for you or the charcoal canister if you don't have that they are both switched 12v and are wired to the "gauges" fuse. Even the AIR system has 12v switched but thats on the other side of the engine.

 

I believe mine is wired to the fuel pump relay, with a 3 amp fuse.

 

sure it can get turn key 12v a number of ways. I was going to tap into the fuel pump relay circuit but I also have a few plugs from my smog/ac that I took out that has 12v with key forward