Given that you've explored most of the reasons for that code, and that that's your only code, it's time to explore every possibility. Make sense?

 

Makes sense, but what is left to explore besides o2?

 

Any other ideas?

 

You might want to look into the cats being clogged. I am having the same issue new motor and all. My mechanic replaced one and it ran alot better but not perfect so they are doing the other side today. We will see what happens!!!!

 

Have you seen this page:
https://repairpal.com/OBD-II-Code-P0171-and-P0174

 

so my problem was not the other cat it was the #4 fuel injector. Hope you can figure out what is wrong with yours. Good luck

 

If the cat is clogged run cataclean through the fuel system it does work. I used it to clean my cat out.

 

in don't think it's clogged cats because I lowered my y pipe and it still ran like crap..

 

what code were you throwing? I have been thinking injectors. Cause it happened after my cousin took my intake off. The first time they tried to take the rail off cause they couldn't get the quick disconnect off....When they got it off they put the injectors that they had gotten out back in...

 

Need a scan tool with live data viewing to be sure, everything you have stated makes me believe they may have kinked or pinched the new intake gasket (O-ring) and/or cracked the manifold by over tightening it, I would want to look at how the O2 sensor is switching in real time, it may be going bad.


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