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Recently bought a 2012 1LT w AT. This simple "bottom of the line" model is perfect for me, and I'm very pleased with it except for one thing.
I can't get used to the rough and low-RPM idle. This idle is best described as "irregular" and it feels like not at all like the "lope" I associate with a high-overlap cam (e.g., an old C1 with a ...097 "Duntov" cam, which had a beautiful lope...but I digress).
My car idles like it has an irregular misfire, but I suspect it is not misfiring (would trigger light, etc.). I can feel the car slightly shudder at irregular intervals. Moreover, I'm astonished at the low RPM at idle. Assuming the tach is reasonably accurate in this range, it reads 500 to 550 RPM at warm idle. Cold idle is also rough and only slightly higher RPM.
I noticed this oddity before I bought the car. Dealer said it's normal and started a couple of other 2012 Corvettes with LS3s to convince me.
Also I've read through lots of prior posts and I know that this subject has been discussed quite a bit. But it seems like some basic questions haven't been answered in a convincing way. So I would appreciate hearing from other LS3 owners and/or general corvette experts on:
1. Is the irregular idle I describe normal?
2. Is 500-550 RPM warm idle speed normal?
3. Has anyone ever got an interesting response from a dealer re C6 LS3 rough idle issue?
4. Perhaps this is esoteric, but what causes the irregular idle I'm describing?
5. Also esoteric: If 500-550 RPM idle is normal (my prior Infiniti G37 coupe idled smoothly at 700 RPM), why does GM set the idle so slow? My guess is maybe it relates to emissions certification and fuel economy rating.
6. If others have had this concern, have they successfully just learned to live with it?