Replaced 02 sensors now hard to start???

[03svt]

1996 mustang, replaced upstream 02 sensors and I had a hell of a time to start, once it is running it stumbles heavy while trying to bring revs up.

WTF....

[03svt]

Disconnected the battery for 25min and seems to be fine now... strange

[Ghost Rider]

that's good...I was going to suggest maybe the sensor was no good to begin with perhaps...

[Laffs]

Is this on the notch?

[03svt]

that's good...I was going to suggest maybe the sensor was no good to begin with perhaps...

Was starting to think that too!

Is this on the notch?

Yup, done a ton of work to it over the last few months... 96.5% sorted haha.

[Laffs]

Does it have long tubes in it? Can't remember, I know with some the distance does funky shit with unless tuned.

[03svt]

Does it have long tubes in it? Can't remember, I know with some the distance does funky shit with unless tuned.

It does have long tubes, I got a canned tune from Diago last week, which was another crisis adverted with that not being able to load the tune from my SCT X3... faulty ignition switch was the culprit.

[ZR]

While it's not common it can happen when you change any sensor until the ECM sorta refinds it's way, similar to how it can run funky after just battery disconnected or gone flat.