I have a 1997 f-150 with the 4.6 engine and suddenly when I started it yesterday it had a loud knock. I have a edge programmer so I programmed it back to stock but its still doing it. It sounds like the knock Is from the valve covers on both sides. Any ideas?

 

If it's doing it on the stock tune, something may be internally wrong, hard to tell over the internet what the sound could be. Go get it checked out. And no the Edge didn't cause it.

 

Could it be the oil pump? Someone mentioned today if it went out oil wouldn't get the the valves and they would knock

 

Is the oil light on? If the pressure is low enough that oil isnt reaching the top end then its low enough for the light to come on.

 

No the lights not on. This all started when I changed my plugs. I changed them back to old ones cuz I thought I might have the wrong ones but still same knock

 

Valves and lifters tap they don't knock.

Sounds like something heavier and more serious than valves.

 

If oil pressure is reading correctly and and its running fine.. take the belt off.. and see if its still knocking... I have seen ac compressors and other acerioes make knocking sounds....

Brad said it... Calces tap or tick.... not knock... knocking is usually piston or rod... Or even a Torque convvertor or flywheel