Noob Question - Engine Miss or nothing
08-14-2012, 09:33 AM
#1
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Noob Question - Engine Miss or nothing
I have a new to me 2009 vert. I have owned for a month and am loving it. For background, I did have to replace the o2 sensor when I first got it due to engine light being on. Neighbor took a ride with me the other day and at a stoplight asked if the engine was missing due to fact that car was kind of "vibrating" slightly at idle. After thinking about it, car has done it since day one but I attributed it to the fact that the engine is putting out so much torque and it was just the "corvette rumble". Any insight from you knowledgeable ladies and gents is appreciated.
08-14-2012, 01:41 PM
#10
There are a number of C6 forum threads on this subject. Search "rough idle", "irregular idle", "idle RPM", etc.
There is also a GM TSB on this subject, which is pretty useless because it basically tells the service technician to check some other vehicles with similar LS engines and if some also have a similarly irregular idle then tell the customer that this is normal. This is in fact what I was told when I asked my dealer about the low-RPM (500-500) irregular-with-mild-shake idle (not a cam lope) when I brought my 2012 base coupe in for its first oil change. (I should add that this is the ONLY complaint I have about my 2012.)
As far as I can tell, some LS3s do this more than others and some have a relatively smooth idle. I think but am not sure that this is random and not dependent on exactly which year, equipment, etc.
My wild guess is that engineers set the non-adjustable ECM-controlled LS3 idle as low as possible (most owners report 500-550 RPM) to maximize the EPA fuel economy test score, and this somehow results in the irregular-shake idle characteristic that some LS3s have. Even wilder guess: C7s will not have this characteristic.
There is also a GM TSB on this subject, which is pretty useless because it basically tells the service technician to check some other vehicles with similar LS engines and if some also have a similarly irregular idle then tell the customer that this is normal. This is in fact what I was told when I asked my dealer about the low-RPM (500-500) irregular-with-mild-shake idle (not a cam lope) when I brought my 2012 base coupe in for its first oil change. (I should add that this is the ONLY complaint I have about my 2012.)
As far as I can tell, some LS3s do this more than others and some have a relatively smooth idle. I think but am not sure that this is random and not dependent on exactly which year, equipment, etc.
My wild guess is that engineers set the non-adjustable ECM-controlled LS3 idle as low as possible (most owners report 500-550 RPM) to maximize the EPA fuel economy test score, and this somehow results in the irregular-shake idle characteristic that some LS3s have. Even wilder guess: C7s will not have this characteristic.
08-14-2012, 04:50 PM
#11
Le Mans Master
