I have a 1999 v6 Camaro and whenever I start it up it makes a knocking sound and the check engine light is on. When I take off it stops the knocking, then when I stop it starts again. I think it maybe the clutch because it starts when my foot is on it at a stop.

 

sounds like a bad rod bearing. Sick

 

What happens when the trans is in neutral and your foot is on the clutch?

 

It may be bad lifters when your at idle they have less oil.

 

I agree with Sick. Bad bearing and low oil pressure at idle will cause a knock, as the engine revs oil pressure rises & knock goes away. Eventually it will get worse, resulting in spun bearing, seized engine, or a rod out the side of the block.