'00 accord pinging under partial throttle
 

Ok, so I have a 2000 Accord LX 2.3l, F23a1. I can't figure why it's pinging. It starts pinging at like 40% throttle, but goes away if I push the pedal a bit further. The issue is only present below 3000 rpm. Any ideas why it's pinging? I have new Ngk plugs, and am running 91 octane ethanol free gas. Please help!

Is the check engine light turning on while driving? Most auto parts stores will scan the codes as a free service. Post any codes on here. They start with the letter P and have four numbers, like P1234.

Check engine light is on, I don't remember the exact code number but it
Reads 'catalyst system efficiency below normal'. It came on after I had a test pipe installed.

Get the codes checked again. You may have a new code that is appearing.

Ok, I'll pull the codes again when I get off work. But the problem has existed before I ever had the cat removed. I was actually hoping the cat was clogged and the test pipe would solve it, but the pinging is still there.

Stop at an AutoZone...they will check it for you for Free...

catalyst system efficiency below normal can also mean an o2 sensor.

Well I have a plx kiwi Bluetooth adapter so I can pull up the
trouble codes on my phone.

I'll go get new o2 sensors and report back I guess.
What's a good brand o2 sensor for this car?

Is this test pipe still installed?

Yes the test pipe is still in place.

Why do you ask?
Would I be better off getting a catalytic converter put back on?