Lean diagnosis

I have an ‘04 2.7 with 240k. I had a p0171, my long term trim was about +22. I found a good sized air leak where the cat pipe bolts to the header, got the manifold bolts cleaned up and corrected that. I also put in a new a/f ratio sensor (

$146 Denso 234-9001 Upstream Air Fuel Ratio Oxygen Sensor with 10.6” 4-Wire Harness, for Auto Trans Equipped Vehicles

Denso 234-9001)and cleaned my MAF sensor, also changed fuel filter. The code went away, but the funny thing is the long term trim didn’t move, and now I get a slight ping under load. I have a scanner that can do primitive graphing. Any suggestions for diagnosis with the scanner or otherwise and/or why the ping would come after the work I did.

 

Did you reset the ECU after the work? Either by pulling the EFI fuse, or disconnecting the battery?

 

Mine popped up a month ago. I cleaned the MAF sensor and got a new air filter (it was looking a little gnarly). It ran a bit smoother and I cleared the code. A month later (2 days ago) it popped back up. Now I'm gonna plug my scanner and take a look at my trims.

 

Thanks for the responses guys. Yeah Andy, I pulled the battery cables off for a while to make sure.