95 cv engine knock

I get a strange knock from my engine only after it warms up. only knocks at high speed full throttle, or when cruising feathering the gas, nowhere in between. tried higher octane gas and every oil addative imaginable, nothing changes. I do have a plugged egr port on the intake manifold (haven't gotten around to fixing it yet) but I don't know if that would cause the knock. seems to come from the rear of the passenger side cylinder bank. any suggestions anyone can offer are greatly appreciated. thanks in advance

See if you can get it to knock a little in park. Have an assistant listen from outside the car to see where it comes from. Hopefully, it's not the bottom and of the motor. Could actually be a catalytic converter knocking. If so, you should definitely be able to tell where it comes from.

JimBob,

What you describe is CLASSIC "spark knock". On a '95, there are three things you can do to lessen this quickly:

1) Use the next higher octane fuel.
2) Remove the "spark timing spout", this will retard timing about 2*.
3) Clean the EGR passages where the upper intake (throttle body) bolts to the lower intake at the rear-center of the engine.

Another very common cause is a cracked EGR tube from the RIGHT pipe/manifold up to the EGR valve. It is imposible to see unless you are under the car (safely supported on jack stands etc) with a good light and mirror. It is a convoluted stainless steel tube (looks like flexible gas line for your stove).

I really appreciate the help. have tried higher octane gas, doesn't seem to help. knock is from the top of engine, and I recently replaced the egr tube. guess I'll have to pull it apart and clean out the manifold too. Thanks again!