so when i start up my car when it hasn't been started in a few hours it revs up to about 2000rpm or whatever but as it come down i hear 3-4 knocking noises, any ideas?

only happens when it's cold

 

Are u using cheap gas???

 

nope, 93 octane only and i use full synthetic oil if that would make any difference

 

Have u tried putting any octane booster or any other type of fuel system cleaner in ur tank. It is possible that u have carbon build up in ur combustion chambers or evn on the piston itself.......just a thought

If i were u i would also clean my throttle body IAC valve and make sure ur plugs are gapped properly.....just a suggestion

 

but why does it only do it when it hasn't been run in a while and only when the rpm's are coming down?

it only happens on startup btw

 

bump!

 

are you sure its engine related?

Kind of odd it only does it on start up when cold.

 

pretty sure, it's definately coming from the front of the car, my dad suggested that the head weren't well oiled but that doesn't make sense because it would make that noise immediately instead of when it's coming down

 

so this morning was the first time it was below freezing and when i started this morning it knocked 5-6 times instead of the usual 3...so it seems it knocks more the colder it is

any ideas at all why?

 

would have to hear it in person