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Oxygen Sensor Question

67ChevyRedneck

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67ChevyRedneck Enthusiast

67ChevyRedneck

Posted
Posted

Hey all,

 

My trucks up to 99,500 miles (2000 Z71 w/ 5.3) and on my last two trips (75% highway) I got fuel mileages of 15.5 and 14.8 when before on the same trips I was getting 17+. I've been driving this route at least once a month for 3 years and have never gotten below 17 mpg (even on winter blends).

 

I'm suspecting the o2 sensors. I'll also be changing the plugs, wires, fuel filter, air filter, and a sea foam job (sounds kinda dirty, doesn't it? :cheers: )

 

The truck has not thrown any codes, but I'd like to test them before I buy them (about $350 for all 4!!! ) Chiltons says you can use T-pin connectors to connect the plug ends (you unplug the sensor, put the pins between the two) and test the voltage to see if they are within specs. The problem is, I have no idea what a t-pin connector is and where I can get them. I'm mechanically competent (I "home bulit" the 67 in my sig) but I'm lost with these connector things.

 

I already ran a vacuum test and the cats are not plugged at all.

 

If anyone has done this or can helps, thanks a bunch.

 

I have a feeling I'll just be blindly buying sensors though :flag:

98 Z71 SLT Senior Enthusiast

98 Z71 SLT

Posted
Posted

As far as "testing" your oxygen sensors, well, you have a little friendly electronic device that is CONSTANTLY monitoring them.

 

It's called your PCM.

 

If you truly had a bad sensor, you would definitely be getting SES lights and trouble codes.

 

I would really just do plugs, wires, air, fuel, PCV and that's it.

Don't waste your money on replacing "good" parts.

67ChevyRedneck Enthusiast

67ChevyRedneck

Posted
  • Author
Posted

I don't think that's 100% true. After reading thread after thread on this board and a couple other places, many people have said that the sensors can get "lazy," which means they won't throw a code, but they're not running within their original specs and are causing excessive fuel consumption, the PCM compensates for the "laziness" and no code this thrown.

 

You're sarcasm isn't appreciated, I know what a PCM is and what it does.

 

Thanks :flag:

mattro Enthusiast

mattro

Posted
Posted

i did plugs wires distributor cap rotor oil change and air filter did notice a thing....i plugged in a obd II or whatever and it didnt have a code for the oxygen sensors so i believe them to be still good at 94,000 miles. The idle did drop after all that and the seafoam i pored in the TB and crankcase and gas tank lols....didnt notice fuel economy. I can usually get 300 out of my 25gal 320 if im really lucky. most i can get in city 13.5 probably and on the freeway driving on mostly flat land to arizona a wopping 425 miles so 17mpg. When i get on it on the freeway i got 250 to the tank ha ha 10mpg but only when in a rush. I think if i had a v8 it wouldnt strain the engine as much and id get better mpg but hey the 5spd helps the 4wd chassis doesnt

firefighteremt3100 Enthusiast

firefighteremt3100

Posted
Posted
I don't think that's 100% true. After reading thread after thread on this board and a couple other places, many people have said that the sensors can get "lazy," which means they won't throw a code, but they're not running within their original specs and are causing excessive fuel consumption, the PCM compensates for the "laziness" and no code this thrown.

 

You're sarcasm isn't appreciated, I know what a PCM is and what it does.

 

Thanks :flag:

 

I dont think he was being sarcastic. At least I didnt read it that way. I read it as he was explaining it in plain english is all....just my two cents.

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