I have a 93 Mustang GT with a Vortech SQ-Trim and all of the usual goodies.

When mashing on the gas pedal (WOT) while on 5th gear from about 2800rpm , i hear what i believe is the engine pinging as the rpms increase.

This is only happening on 5th gear.

When racing through the gears with the gas pedal on the floor, no pinging is heard.

I've change spark plugs to 2 ranges colder, replaced with wires, checked timing - 10 degrees, cleaned the TB, cleaned the Idle Bypass valve, checked TPS- .95volts, cleaned the mass air sensor & tightened the header bolts... Still the same.

What could be the problem?

 

Is your balancer stock or aftermarket?
If it is stock make sure the balancer didn't spin giving false timing readings.

 

what kind of gas and how much boost are you running. in you highest gear while under load is when you usually get pining. try going to a higher octane fuel or even dropping down to 9* timing

 

what size injectors? is it tuned?, what size pump is it? what octane you running? so many things could be the issue

 

for real..what psi?.... what plugs..and if you herd pinging while racing you'll be about 1 min from a new head gasket..the car needs tuned....I hope you atleast have a fmu or larger injectors