[PeteA216]

Hey everybody. I've got a 1989 GMC Sierra 2500 4x4, 5.7L 350, TH-400 transmission. Tranny's new with about 8,000 miles and the rest of the truck has about 130,000 miles. Within the past few months the truck's been having an incresing problem with engine ping. At first it was sometimes under acceleration, not too bad. But it worsened so I ran middle grade fuel. That fixed it for about a month until it started pinging again the same way. Now I'm running premium, and its beginning to ping lightly on that during express way acceleration. I replaced the knock sensor, and it had no effect, still pinging. Now what? I used teflon tape to seal knock sensor's threads so coolant wouldn't leak. Should I have not done that? Any ideas as to why the engine is still detonating like that on me, even with 93 octane fuel? Thanks in advance for any help!