upstream o2 sensor

[ashleyroachclip]

wifes 91 ex. was running really poorly, found it was low on coolant , and the cruise vacumn line had come off.
Reconnected it , filled the coolant level up , ran codes.
What I came up with is , upstream o2 sensor lean ,,51.00 for a new one ...
the truck runs good after it warms up . when you try to start it in the morning, you have to crank till it starts , a sec or so , then it dies , then the same , a sec or so , on the 3rd try it starts and runs but rund rough , as it warms up it smooths out .
Once the truck is warm , it runs fine , not as well as my ranger w/4.0 but pretty well .
I can't stand to listen to her complainn as to how well my truck runs and how hers does not . any help would be great , and I'm figuring up stream , means before the cat ?

 

[MrShorty]

On a '91 "Upstream" means "the only" O2 sensor there is to be found. It's at the Y-pipe junction just upstream of the CAT.

Assuming the code is a memory code and not a KOER code, I would simply clear the code and see if it comes back. A vacuum leak as one could have with vacuum lines disconnected could set an O2 sensor lean code.

 

[ashleyroachclip]

91 explorer .

thanks for the reply , I've not been up under the rig , I assume you are saying only one o2 sensor , that would be cool ,cleared codes and will see if it has come come back.