No clues as to what year.... does it knock even with premium? Try several different tanks from several different stations since the fuel can vary a great deal.
If it still knocks, and yours is a 2k or 2k1 Maxima, the problem could be the ignition coils. There's a TSB on the problem. If your car is out of the 3/36 warranty you'll have to pay for the repair.
BuddyWh
My engine knocks at about 1/8th throttle. Like when I go around a
>curve at 35 or 40 mph, or coast downhill. If I take my foot off the
>gas or I push it a bit farther, there is no knock. Why do you suppose
>this happens? what kind of problem is this, if it is a problem?