My moms 01 Maxima is acting strang... it keeps throwing trouble codes for missfire, bad ignition and depleted catalytic performace... BUT there is also a very loud ticking/rattling noise that comes from the front when the motor is under load like if you step on the gas to pass someone, get upto speed or go up hill from around 1400-2500rpm... imagine someone with metal fingernails typing... thats what it sounds like....

the mechanic replaced the plugs, wires and a coil, but the codes threw a few minutes after. ive tried many times to scan her obd2 but i found out nissan has thier own codes and shit and doent work with my scanner or laptop.

any clues?