Nasty pinking problem on 99 Z28

What is your timing set at? Most chevy smallblocks at +6 degrees. Your timing setting should be posted on a sticker under your hood. Sounds like the timing is far advanced IMHO.

The LS1 used in a 99 Z28 does not have an timing adjustment. No distributor, no timing marks. Timing is totally controlled by the computer. - Gary

Could be a failure in one of the following:

Head gasket - usually accompanied by water loss - it's the water in the fuel mixture that causes the pinking

Intake gasket - allowing additional air in, resulting in weak mixture on one or more cylinders - and you might get rough idling and hesitation on pickup.

Any one of a number of electronic sensors - as Gary said, the timing is totally controlled by the computer - the computer decides where to set the timing dependent on several inputs; engine speed, load, exhaust analysis, atmospheric conditions etc., and ultimately two or more knock sensors. These are located on the engine block and physically detect any pinking (or knocking). If pinking is detected, the computer retards the timing until it stops. If a knock sensor isn't sensing, the computer doesn't know to retard the spark and you hear the pinking. An OBD readout should pick up a failure any of the sensors.

Good luck !

distributor,