major knock

[grandprix34]

well im getting serious knock.

Now that i have the FFP chip i rev it up slowly in park to about 6 and just let the accelerate go and i can hear loud knocking. I heard it could be the timing.

Since i timed the car, the stuttering/vibrations/loud ugly noise has left. The shifting is smooth now and the car runs flawlessly. Then about 4 days ago, it didnt want to start. After about 3 cranks it caught but when accelerating from a stand still it felt slugish and heavy. At high RPMs the engine would knock once the acclerater was depressed.

So im not sure wat it could be...bad cat, bad fuel, bad something....lol

wat do you guys think?

[95gtp]

I dont think anyone is blowing you off but there are a number of things it could be like you described (cat , fuel....).
Any smoke, leaks, or other signs of trouble? What have you looked at so far?

[Homer]

I would check to see if your timing is still set correctly.

[Guest]

Your engine is probably about to blow up...mine did the same thing..

[jmgtp]

High rpm decel only? Hmm... I'd get that car up on jackstands, start it up and have a listen to the bottom end. Maybe use a stethoscope, although I imagine that would pick up a lot of static noise, maybe a block of wood pressed against the oil pan and your ear listening at the other end would be better. You could drain the oil and cut open the filter to look for particles.

[pocket-rocket]

When I had the auto in the 91, it used to do that sometimes, but it would be from about 3k down to idle. I definately sounded like a knock, but it was in the tranny, not the engine. Also, a while later, it started making a similar sound, but this one had more of a rattle to it. The first one I never found out what it was. The second one I found out was the bolts that hold the torque convertor to the flexplate had worked their way out some.