So here’s the long story short:
1997 f150 4.6 lariat and I’ve got the inevitable spark knock. So I did all my research. Checked all vacuum lines, no leaks. Check maf flow and cleaned it just for fun. No issues with egr tubes or components (all cleaned or replaced). Replaced all plugs and wires. Even tried one step colder plugs. Issue only occurs under a decent to heavy load aka climbing a hill or flooring it to pass. Issue is almost gone running premium gas but not completely.

From what I can tell it seems like my bank 2 is running lean cause the computer thinks it’s always rich. Been watching my o2 sensor data for a while and my bank 2 basically seemed lazy but I replaced both of them and they still act the same. Mostly running at .5-.8v and doesn’t fluctuate like bank 1. My though was it is a clogged cat but before I invest in a new one I wanted to see if anyone has any opinions to track down.

Freeway driving

At and off idle

Climbing a hill

 

What O2 sensors did you use?

 

It was an Amazon part (I know I know, cheap China junk) kax 15717. 4 wire just like the one I pulled out. If we’re thinking that might be the culprit I’m not beyond swapping the bank 1 and 2 sensors even if everyone says the right side is a royal pita.

 

The trouble with China junk is it causes people to have to do the same job twice. I would rather pay a little more and do it once.

 

for something that took me 5 minutes to do I’ll risk it. Heater core on one of these... no way, not even an autozone part.

 

These trucks are pretty picky when it comes to O2 sensors. They really like Motorcraft, NTK, or Bosch only.... Motorcraft / NTK's are better and have a quicker response though. The problem with Chinese O2's is exactly what you are experiencing. They are lazy....

 

Just compared the prices of what you ordered vs. Rock Auto. Looks like you "saved" about 20 dollars.

 

just because I’m curious and can return the cheap ones if they are in fact not working I went ahead and got the ntk ones and will report back with results.

 

Reading this, I thought immediately about a stretched timing chain. That would cause a problem like you described.

 

I would hope not at 130k but anything is possible. If this doesn’t help than I may look into that. But the reason I didn’t look into more was cause premium makes it almost completely go away. The second I put regular back in its back to obvious noise when I push the pedal hard.