A friend of mine just bought a '07 z51 vette that has some serious noise and idle issues. Since we have the same engine, he asked me to see what I though the problem was. It clicks (injectors and valve-train noise) like crazy and the idle is so rough that it moves the whole car side-to-side. The car also surges while moving at idle. After driving it and pulling off the valve covers (to find no modifications) I am down to one thought as to what the problem might be.

The previous owner used to have headers and some other mods that were pulled off before the sale. It is very possible that the car had a cam in it also. My thought is that he had the car tuned to work with his mods, but didn't have it re-tuned after he got the mods pulled off. I would love to hear some feedback from any of you experienced ls guys.

(I know the engine is in a vette, but I think this thread is CTS-V forum-worthy since the problems are wholly related to the LS2 and the solution could help out a forum member in the future)

Is there a possibility of a vacuum leak anywhere? Maybe there during the mod process some gaskets or hoses weren't aligned or reconnected properly. Just a thought.

possible bent pushrod? Could cause the noise and the poor running.

Those three possibilities plus ...

broken valve spring,

misfiring cylinder (broken spark plug, bad/disconnected wire, etc),

bad motor mounts,

water in gas,

disconnected coil wire,

...

...

...

The noise is very consistent and it is very apparent when you are decelerating with the car in gear at high RPM's. It is a constant sound and not one that could be caused by just one bad component unless it was effecting the whole valve train equally.

That rules out a lot of those, but not all.

can you post a video of it?

can you post a video of it?

I might see him this weekend. I'll carry my camera in my car just in case.