Hi everyone, I have an 89 350 tuned port with headers and a one wire o2 sensor causing problems. Trying to switch to a heated 4 wire o2 sensor and save a few bucks by getting a used one. Got 6 different o2 sensors from the junkyard today.

I think I was told I need an AFS74. One of the threads I searched on said that can be found in a 95 s-10. I took a couple out of 95's, 96's, and 2 real nice ones out of a 98. Are these all the same?

The best I can tell they have numbers as follows....

AFS 75 ( out of a 95 s-10)

AFS 75 (out of a 95 s-10)

AFS 105 ( out of a 96 s-10 I think)

AFS 105 ( out of a 96 s-10 I think)

Then the 2 REAL nice new looking ones I got out of the 98 don't have an AFS #, they just have some long part number on them....

1rst one is...... 0 258 005 703 5902631 12V 982

2nd one is...... 0 258 005 703 104132 12V 982


Can anyone tell me if any or all of these will work since none of them say AFS 74?

Anyone who may know and could tell me would be greatly appreciated. Thanks

 

I think that bosch 0 258 005 703 is the same as a afs-75 4 wire
https://www.thirdgen.org/forums/elec...-how-do-i.html

 

Good news! Looks like I saved 40-50 bucks.

 

Next round of beers on you

 

sounds good!


Now on the wiring.....

I copied and pasted the following..


A pigtail to connect the stock o2 is easy to build with packard connecters from mouser.com. You can hook the ground to a bell housing bolt the purple signal wires connect together and the accessory hot can be hooked to the cooling fan relay. Jims performance.com has the pigtail for I believe $20 amazon always has good pricing on the afs-74.


Now, I'm trying to use the newest Bosch o2 sensor that has 2 white wires, a black wire, and a grey wire. Is it safe to assume I should connect the 2 white wires to my old o2 wire, the black to ground, and the grey to 12v ignition source?

 

grey is the signal. the whites are both for the heater iirc. black is the sensor ground iirc

 

I put both whites to signal and grey to 12 volt already before I came back in to check if anybody replied. It drove awesome and I could have swore it even pulled harder with more power but I might just be imagining it. No check engine light.

So am I just driving around in open loop with it hooked up wrong?

 

You can watch the engine enter into cl with the aldl a to b jumped.

 

I'm going to redo the wires now but the diagram TP attached says I need to run both whites to heater ( I'm assuming they get twisted together and hooked to my 12v power source/ not one to + and one to ground ?). Then it says my black wire is signal and grey wire is the ground.


BUT.......

2 posts before that I'm told by someone the grey is signal.

Should I go with the diagram for the 4 wire option a?


Right now off the diagram I'm thinking the following...

White = 12v
White = 12v
Black = signal
Grey = ground

Can somebody confirm?

 

tp knows better then me. i havent wired one up in 4 months so it isnt fresh. i just remember white is the heater circuit. it was in open loop.

one white is 12v+ and one white is 12v-. doesnt matter which is which.

 

I havent used a four wire one in years so all I could find was the pic. Maybe a coin toss

 

Well I'm going to guess since I grounded my black wire originally and didn't have a CEL that it must be the sensor wire and grounding it just fooled the computer into thinking it was hooked up. I'll wire off the diagram tonight and also ground one of the whites this time and let you guys know what happens. Thanks!

 

Well I got the heat wires right ( the 2 whites) because it gets hot now if you hold it in your hand with ignition on.

I tried the black wire to signal and grey wire to ground and it acted the same, still sets code 13.

So I switched the wires ( black to ground and grey to signal) and still acted the same way. Set code 13 again after driving for a little bit.

Unrelated but my speedometer cable must have broke. Now I'm showing codes 13 , 24 , and 34 whatever those are. Suppose they are speed sensor related.

I'm gettin aggrevated.

 

Any ideas on what I should do? Either I messed up my computer by hooking something up wrong or o2 sensor not compatable?

Any thoughts would be appreciated.

 

Im wondering if the 02 got damaged when it was hooked up the first time. ou can check the output when its warm and the engine is over 140f with a vom. The output will swing on a mv scale over 9 to below 4.

 

I wandered the same thing so I put another new looking Bosch in there but can't remember which way I had the remaining 2 wires hooked up before test driving and switching again. I'll try one of the older AFS-75 sensors when I get home, if it still does it I'll switch the 2 wires in question ( since I know the heater is working with the other 2 wires), then put another AFS-75 sensor in and try again. That should fix it or eliminate the possibility assuming all the used o2 sensors I ended up with are good.

I might try the volt meter idea too and see what kind of voltage I'm getting.

Thanks

 

Well I tried a stock AFS 75 with the 2 possible wires wired both ways and both times it set a code 13.I tried figuring out the volt meter but I'll have to wait for my son to get home since he had a college class on auto electrical. I'm guessing "vom" means voltmeter and "mv scale" means millivolts.

I read the signal volts I think from the o2 and it seemed to be right at about 4.00 for a couple minutes then started going haywire. ( jumping around to 6-9-12-14-16-15-10-16-etc.... for example. I probably did something wrong. I had multimeter set likeI would if I was reading alternator output.

 

I tried to attach a picture of my multimeter. I know this sounds stupid but could someone tell which position I need to have this thing in to read the millivolts of the o2 sensor?

I'm trying to get set up with an aldl cable and software soon but for now I have to work with what I got.