Rough idle
Thread Starter
Intermediate
Joined: Jan 2016
Posts: 34
Likes: 12
From: S.E. Michigan
Rough idle
Ever since my c7r was new, (last christmas) it has idled rough. Not so much like the cam loping. It is still just as bad, maybe worse. Is this a common condition? We have been tracking the car and enjoying it imensly. Hence my previous post on track-race mode (still held back). Got it straight now but have not gone totally "naked" with the 11th setting. And really don't need to. It was just good to know GM is looking out for us. Drive on!
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
If there were any misfires, the OBD2 system would detect that within about half a crankshaft revolution, and you'd wind up with a Check Engine light. Not much worse for catalytic converters or emissions quality than to have a cylinder not firing properly, so they actually are able to measure the acceleration and deceleration during and after a cylinder firing event. If it doesn't happen correctly, misfire is detected.
The Z06 has just enough cam that you'll feel it through the car, but it is by no means lumpy. Thus I'd say if yours were any more so, it's indicative of a problem. But if it were, you'd have a light on, and presuming you don't, I think "all is well".
The Z06 has just enough cam that you'll feel it through the car, but it is by no means lumpy. Thus I'd say if yours were any more so, it's indicative of a problem. But if it were, you'd have a light on, and presuming you don't, I think "all is well".
2nd Gear
Joined: Sep 2016
Posts: 2
Likes: 0
Rough Idle
I just purchased a 2016 C7 Z51 and was told by the salesman that the car was designed to idle a little rough. Its not annoying and I kind of like it. The car runs as smooth as silk while driving. Looked up several corvette forums and read that GM designed the car this way.
Have my first oil change coming up and will have the dealer check it out just the same.
Have my first oil change coming up and will have the dealer check it out just the same.
Melting Slicks
Joined: Feb 2015
Posts: 2,122
Likes: 452
From: Syracuse-Central Square New York Winer of the all Corvette race WGI 8/23!
Ever since my c7r was new, (last christmas) it has idled rough. Not so much like the cam loping. It is still just as bad, maybe worse. Is this a common condition? We have been tracking the car and enjoying it imensly. Hence my previous post on track-race mode (still held back). Got it straight now but have not gone totally "naked" with the 11th setting. And really don't need to. It was just good to know GM is looking out for us. Drive on!
I will take a guess and say its a lazy sensor.
Melting Slicks
Joined: Oct 2007
Posts: 2,398
Likes: 858
Ever since my c7r was new, (last christmas) it has idled rough. Not so much like the cam loping. It is still just as bad, maybe worse. Is this a common condition? We have been tracking the car and enjoying it imensly. Hence my previous post on track-race mode (still held back). Got it straight now but have not gone totally "naked" with the 11th setting. And really don't need to. It was just good to know GM is looking out for us. Drive on!
Thanks
Instructor
Joined: Dec 2013
Posts: 118
Likes: 14
From: Bay Area CA
Less than 900 miles on my Z. Idle is a bit unstable too. It will dither up and down a little, causing the car to vibrate a little. Feels like a larger cam than what it is. No other engine issues. Probably nothing, but it's slightly annoying at times. I'll scan it to check for DTCs. Seems like it's functioning as intended though.
Drifting
Joined: Oct 2005
Posts: 1,331
Likes: 479
From: Appleton Wisconsin
Mine does the same thing, almost like a slight miss but not a constant miss. Has to be one of the sensors not responding quick enough. A bigger cam has a uniform thump thump. I wonder if the AFR is too lean at idle? Is there a way to check the AFR at idle to see what it is and how much it varies?
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Advanced
Joined: Jun 2005
Posts: 98
Likes: 13
From: Madison MS
Same thing here. A slight roughness in the idle that isn't consistent. My C6 did the same thing. Never bothered me enough to have it looked at and, in the 10 years I had the C6, it never got any worse or caused any problems.
Pro
Joined: Jan 2005
Posts: 667
Likes: 9
From: Melbourne FL
I had a little bit of a rough idle for the first 300 miles or so but now it seems much smoother. It came to my attention because my C7 Z51 was very smooth all the time I had it. So now with the Z the idle now seems fine but then again maybe I'm just use to it.
Drifting
Joined: Apr 2007
Posts: 1,643
Likes: 633
From: Lake Bluff IL
Funny you bring it up . Just this morning I noticed a bit of a lumpy or rough idle. Hadn't noticed it before. 2,700 miles. Admittedly I tool around town a lot using it as a daily driver, but I also run it out fairly regularly, so it shouldn't be building carbon deposits. Maybe as noted it is just a little idiosyncrasy of a 650 HP engine. I will see it smooths out with some more serious running. --Bob
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
Several years ago I recall reading an automotive white paper that stated a somewhat rough idle was common to many DI engines and one of the major Japanese manufacturers (Toyota I believe) was considering using a dual system with port injection at low RPM to address this and valve buildup. My 2008 CTS and 2014 ATS (both 3.6L DI) have some roughness at idle and Cadillac has new engine mounts available to somewhat disguise this problem although it hasn't bothered me enough to have the mounts changed under warranty. My Z06 also has some noticeable variance at idle but on my list of things in life to worry about it doesn't make the cut 
Advanced
Joined: Jun 2005
Posts: 98
Likes: 13
From: Madison MS
Speaking of motor mounts, for 2014 and 2015 models there is a TechLink article about doing a motor mount alignment to possibly help a rough idle/vibration at idle problem however it only mentions the LT1 not the LT4. http://m.gm.oemdtc.com/TechLink/TechLink2014Oct.pdf