My question is what wire coming from the o2 sensor is the signal wire going to the computer. Second, what are the other two?I figure one is power, signal, ground but hey I dont know. Its a 3 wire of course.

 

One is the info wire, the other two are 12V and ground for a heated O2 senser, which is which is above me right now cause I don't have any of my wiring diagrams with me.

 

Please refer to the pictures attached below. The first picture is what I have found for a '94 which only shows 3 wires. If you had a late model year '94, it could have transitioned to the 4 wire models shown in the 2nd picture. Basically, to improve reliability of the sensor, they added another ground for the sensor part instead of grounding through the exhaust system.

[IMG]local://upfiles/667/70685F05B89741F5BEFB97EB63F25D3F.gif[/IMG]

[IMG]local://upfiles/667/623606A67EB9446596071D1C3A5EB42D.gif[/IMG]

 

my 94 also has 4 wires on the O2 sensor what I found out when I replaced mine was in 94 there were several different ones used, could have anywhere from 1-3 O2 sensors and anywhere from 1-4 wires, why I don't know but this is what the dealer told me when I went to buy mine ended up making sure I only had one and took the old one off and in with me to make sure I got the right one.

 

Thanks for the info. I have a 3 wire, and there is only one.
IfI got a 4 wire o2 sensor, couldI ground it my self to make it more reliable, or what ever swartlkk said?
I dont know what kind of amps, orvoltsthe signal wire uses, butI was wondering ifI lowerd/changed the signal by .5 volts by useing a risistor, or something like that. Would that tell the computer less voltage, so it would think it is lean then put more fule in? and ifI increased the voltage by +.5 that would tell the computer it is rich and lean it out a little. hence saving gas or..... breaking some thing, is this a stupid idea or just unrealistic?

 

honestly I don't know what grounding the extra wire yourself would do. Was just sharing the info I got when I recently replaced mine since they are the same year/engine etc. sorry I can't be of more help.

 

You could use a 4 wire sensor, but you would have to put in a new electrical connection on the truck side of the connection and then ground the wire from there to a good ground. You could simply pull a plug from a junkyard truck with 6-12" of extra wire. I think that the same type of weather pack connectors are used so you may be able to just remove wires from one connector and insert them into the other, taking that extra ground wire to the chassis somewhere.

My statement about reliability is correct. As an exhaust system ages, the quality of the continuity to chassis ground degrades, degrading the effectiveness of the sensor.

Now, about the adding a resistor to richen the mixture... That is a bad idea. If you really needed this, it should be accomplished through programming of the PCM. But unless you have done some major modifications, you should not need to artificially richen the mixture.

 

Nope this is all stock. But I am getting 11 mpg and it is draining my pocket book. The only sensorI have not replaced is my o2 sensor. It is not giving any codes, and it is not hurting for power.I am aware of the winter mixture of fule, for easy start ups.I dont think that is my whole problem, any other sugestions?

 

I get on the average around 20 with my 92 Blazer. 11 is very poor indeed. Have you check the timing recently?

 

The timing is 2degres advanced last timeI checked.