Engine running lean and P0171 code after tail pipe replacement

[jcwhidby]

I recently replaced a rotted out tail pipe on my 1997 Ranger 2.3L. After the tail pipe was replaced the engine started running a little rough at full throttle and the CEL came on with code P0171.

I can’t imagine how a tail pipe could cause the engine to run lean but I’m not sure how to resolve this.

So far, I have checked for vacuum leaks by unplugging the idle air control valve and idle speed decreased to about 550 rpm as expected.

Any suggestions for troubleshooting would be much appreciated.

 

[Vindictus]

i did a quick search and found this https://obdcodelookup.com/dtc/p0171-ford/
I would double check your tail pipe replacement.
exhaust leak is one of the causes

 

[jcwhidby]

I saw that too, I fixed a bunch of exhaust leaks with the new tail pipe, I don’t think I created any new ones but I will look again.