00 GT, 5-speed...car is practically rock stock (no timing advance or CAI). 70k miles. This past winter i started to hear some light detonation under accel on highway in 3rd, 4th, and 5 gears...about 4k to redline. Became progressively worse throughout the winter...I've run pure 93 through it with the same results. It's fine for everyday driving but I can't floor it with the way it is now.
Just recently changed the fuel filter and plugs. The plugs that came out where the original plats and were scary white...I replaced with autolite coppers. I was really hoping it was just a stupid fuel filter but that wasn't the case....It still pings in those gears on highway pulls.
All the plugs looked exactly the same, so i'm ruling out a clogged injector (s). I also checked the TPS (.96v idle and 4.66v WOT) and the PCV (fine).
Aside from checking the fuel pressure, what else can I check?
Just recently changed the fuel filter and plugs. The plugs that came out where the original plats and were scary white...I replaced with autolite coppers. I was really hoping it was just a stupid fuel filter but that wasn't the case....It still pings in those gears on highway pulls.
All the plugs looked exactly the same, so i'm ruling out a clogged injector (s). I also checked the TPS (.96v idle and 4.66v WOT) and the PCV (fine).
Aside from checking the fuel pressure, what else can I check?