rough idle after engine replacement

[almighty]

so i replaced my engine and trans last week and i have an issue with the way the new engine idles, it seems kinda rough, and trips a code "bank1 too rich" i have a really cruddy scanner so im not sure what is causing this, but would a knock sensor do this? if so i could prolly change it easily enough, but dont wanna do this if its not needed.

any advice would be welcome

[blueguy]

Bank one lean is vacuum leak...I'm guessing too rich is a bad o2 sensor...I could be wrong though.

[blwn3800]

Hmm sounds like you are getting alot of misfires, which could cause the o2 sensor to detect a false lean condition and dump fuel at it. It could also be a vacuum leak make sure you go over all the lines and check that they are all securely connected and not cracked also check the rubber T's and fittings its very common for them to dry out and crack. Check your plug wires make sure they are tight on the coils and plugs. Another possibility is a bad FPR or leaky injector i'm not a 100% on how to test it on your car but someone else might chime in. Might also be an exhaust leak upstream of the 02.

it could be alot of things when it comes to a rich condition and rough idle, but it is usually the 02 compensating for something. but my money would be on a vacuum leak or bad 02 . hope this helps and you get it figured out