sorry for not looking threw the old post but as i don't realy have much time of the day to get onto a computer....sorry[:-]

I have decided to change my 02 sensore to try to get some better gas mileage.
well i looked in the repair book i have, and they point me to the thing comming out of my right exhaust manifold (if your facing the front of the vehicle) so I went to the auto parts store to go get one and they have two types. An Upstream and a downstream..... have no idea what the diference is cause i don't think i have one by the catalytic converter. plus all the downstream ones were universle, meaning i would have to cut and splice my wires, don't realy want to do that, so is the upstream one the type i want or are there in fact 2 of them and if so which one usually craps out first.

 

First off, are you throwing a code? Even on an obd1 system, an O2 will still throw a code. If it isn't giving a code, then they are telling the computer that it is still getting a good reading. Therefore, not beneficial to replace.
You could put the money towards gas.

 

A 1994 Blazer will only have one O2 sensor.

O2 sensors can impact mileage before triggering a code, especially in the OBD1 vehicles with more lax failure criteria. Proper testing should be done prior to replacement unless you like less money in your pocket...

 

well now i'm mad, the wires had melted and were fused together but no code.........very odd yes i know even my dad was scratching his head, so i replaced it with a bosch 02 sensor and now i'm getting even worse mpg [&o]very fustrating, still i hamord it kinda hard once during this weak which could explain the worse mpg but going from 16 to 14? I think i will put my old tps sensor back on because i changed it trying to fix my original problem (stalling at ideling)and seemed to get worse mpg after i changed it.
but i have changed almost all the sensors in this dang thing (all with the highest quality i could get) and i still can't get my 18 mpg back, and i was more abusive to the blazer before. So much for the helpful sensors.
I guess i will scratch my head for a bit and ask around to see if anyone around here has had this problem

 

IMO, Bosch is quite far from the best you can do for O2 sensors... Are you sure you fixed all of the wiring damage?

 

Where is this sensor located, how hard was it to replace, and how much did it cost. I didn't mean to jack ur thread, just wondering if this would be the same deal with my '93 olds 4.3 cpi.
Have you inspected your cpi unit lately or preformed a fuel pressure leak down test? That can have an impact on your mileage... Also an o2 sensor can be ruined if you have any unburnt fuel, oil or even antifreeze making its way down the exaust plumbing and coating the o2 sensor(s).

 

the 02 sensor looked fine except for the wires, i replace the cpi unit in july and made darn sure it was in there properly, and the wires were melted not the conectors,
the 02 sensors on my 94 s-10 blazer was located on the left side of the vehicle underneith the passenger door past were the 2 exhaust pipes joined together.
And I went to the NAPA and they would have sold me the same thing, and the dealer charges straight highway robbery rates for parts. they wanted like $180 for an 02 sensor
I still haven't put my old tps sensor back on yet, hopefully that is the problem because out of all the parts that was the cheapest quality