3800 knocking only in 3rd gear

[LuminousX]

3800 Manual Camaro knock in 3rd car under boost, but not in 2nd under the same amount of boost, what could cause this?

[Vbb1994]

What afr? What rpm? My turbo 3100 would knock in 3rd, I had to play with the afr. When it'd drop in 3rd the engine load would be so great at the lowered rpm, I had to raise the 2-3 shift area to keep the Rs up, and I believe ultimately lean up the afr because it kept knocking on whatever I had at 8-10psi. Lower spark isn't the answer sometimes. It just makes a nastier, richer mix that'll cause a lil misfire and result in some pinging ... sometimes