Knock on cold start

[turbotofu]

When I start the car after not having driven it for a while, I hear this knocking sound for a few seconds, but then it goes away.

I googled and found that maybes its "piston slap?" Perhaps I should try a different oil?

[martins_240sx]

it could be your timing chain guides. there is a right up on here for removing the top one, alot of people do this. with it removed your problem could go with it.