Ping during cold start.
 

When I start my car in the AM, the engine makes a slight rattling sound for about a second and then it goes away and doesn't happens again until I let the car sit for about 6-8 hours. If i don't let it sit for a while, the problem doesn't happen. It drives perfect, no power loss or hesitation, and doesn't make noises except for that brief period of time right after it's started.

This began when the stealership performed the last recall, only changing the sparkies and doing the flash (it's been doing it for a while... thought it might go away but hasn't). From what I've read, it sounds like ping... I guess. All I really know is it wasn't happening before, and now it is, and I want it fixed under warranty before it runs out . I took it in but the dealership couldn't find anything wrong with it.

Anyone got any idea what the problem could be just from the description? I searched around but the only thing I found similar was a problem Charles had with his car, which ended up being from an aftermarket part which I do not have.

I have some sound clips of it, but I need somewhere to put them so people can hear it and I'm opposed to making any new accounts at any free upload service. Anyone got some web space they are willing to donate to the cause? Three files totaling about 900K.

Mine does something like this for less than a second, but it's not a knock, its a misfire. I chalked it up to the new flash calibration. They lowered the amount of fuel injected on startup (or changed the timing a bit) so it cranks a bit before fuel is injected. This means the first couple of firings are too lean and it sounds just like an old manually choked engine when you didn't choke it enough. I don't think its anything to worry about.

Ok that's cool. At least I'm not alone :).