I have a 02 3.0 automatic 2 wheel drive with about 250,000 miles and when you receive past 3000 it starts knocking. It doesn't sound like a rod knock because it is only when it's driving it won't do it at idle. The check engine light flashes on and off for a few seconds then goes off so there's no codes to read. Please help!!

 

Welcome to the forum

Try running a tank of 93 octane gasoline, or 1/2 tank
If knocking goes away after a few days then what you were hearing is pre-ignition, pinging/knocking from the air fuel mix igniting on its own

I thought the 2002 3.0l engine had a Knock sensor to prevent this when running 87 octane fuel(regular), but some years had it other years didn't

The EGR system also prevents pinging but it is a monitored system so you should get CODES if there was a problem there

The flashing CEL(check engine light) means to "back off the gas" because engine damage may occur, so computer is detecting a problem of some kind

I would stop by an auto parts store, most will read the Codes for free, WRITE CODES DOWN, there are hundreds so "I think it was..............." is useless, and post any here