Good Day All. Has anyone ever replaced the stock 1 wire (un-heated) oxy sensor with a 3 wire (heated) sensor? Thanks.

 

Not on a 91 but on an otherwise identical 87. One wire is the signal wire that goes to the ECM same as always. The other two are a 12V+ and a ground. I recall running the 12V+ off the wire that powered the electric fuel pump and the ground to wherever was convenient. After the conversion we could get the ECM into closed loop in about a minute of run time!

I beleive I used the O2 sensor for a 92 'Vette if memory serves. Cheap and effective.

 

THANK YOU for this post. I've been meaning to ask this same question for weeks. Nice quick & effective response too.

 

I need one of these badly on my car. Longtubes do not like stock o2. Takes FOREVER to go closed loop, plus my car is rich at idle in open loop due to hotcam and 24# injectors. Any part numbers or anything for one???? TIA

 

Doesn't anyone search anymore? I posted about this well over a year ago with part numbers, etc. Others have posted about it since then.

Tim

 

There is alot of info on this topic on this website as well as others.

Try this on for size: http://sethirdgen.org/HO2S.htm
You don't have to use the GM HO2S, since it is a little pricey, you could probably try Bosch.

 

I'm confused..is this some sort of mod if you have a TPI that runs rich due to a chip and cold thermostat? If so then I definitely need it!

 

No, its a mod if you have headers that won't keep the oxygen sensor cool. The oxygen sensor is ineffective if it does not reach at least 600° (or somewhere around there). A heated O2 sensor will not only get the sensor hot sooner, but keep it hot.

 

Well I have headers also and my car runs pretty rich. My temp never goes of 170 either(except in summer traffic). Should I get the 3 wire sensor?

 

I moved my stock 1 wire from below the header to the collector and I STILL have a rich mixture. The three wire is going to be my next step.

 

I moved my one wire o2 onto the collector and it still doesnt get hot enough. The three wire set up is my next step to get this piece running right.

 

I used this part # in long-tube headers:

AC-Delco # AFS74 is a three-wire heated sensor. The GM long# is 25312179.

AFS74: 1995 CHEVROLET S10 PICKUP V6 4.3L 262cid GAS FI N Engine VIN = Z
Two extra wires of the sensor connect to 12v source and ground.

They were about $30-35 last time I bought one from- http://www.rockauto.com/

Also, I have a discount code for that site: 550178940
Enter discount code in the "How did you hear about us" line of the shopping cart, receive an immediate 5% discount on that order.
- The discount code expires on November 3, 2003

 

My 91 tpi 305 would not stay in closed loop at idle. I converted to the heated o2 sensor and now and now it goes into closed loop as soon as the coolant temp gets a little over 100*. With a warm engine it takes 30 seconds to go into closed loop. I used the 91 corvette ZR-1 sensor.

 

Anyone ever notice that like every semi-modern car has 3 and/or 4 wire 02 sensors?

I bet you can safely say every third gen could benefit from a heated 02 sensor. Even on dead stock engines, I bet it would help the engine get into closed loop sooner, and keep the BLMs more consistent.

Just a thought...

 

I do but search queary does not allow you to use words like (02)
or (3).
But I did find it on your LTH install tips. Thanks!
I gotta learn to keep silicon products away from mine

02 # 13077 91 ZR1 VETTE.