engine noise
 

can anyone tell me what the problem could be. my 90 z32 has some engine noise while driving under load. can it be timing? how do i adjust the timing on this car? it also happens during the first second when i rev the engine. sounds like pinging or something. can anyone help?

When was the last time the 60k maintenence was done? Also, please tell me your using premium gasoline. If not, then you would get pinging and spark knock.

Yeah, Definately I always run premium in my car at all times, it's a Z you kinda should just outa respect for the car.

Have you noticed a difference in the overall performance of the car? You set the timing on these cars by turning the crank angle sensor. You need a timing light to do this in order to properly set the timing. It is unlikely that the timing adjusted on its own. Has your ECU picked up any fault codes? Pinging is caused by running too lean, i.e. not enough fuel. When was the last time you tuned it up....new plugs, fuel filter, air filter, etc?