Rough start on LS3
Thread Starter
Instructor
Joined: Jun 2021
Posts: 228
Likes: 95
From: Westminster, Maryland
Rough start on LS3
When starting my dry sump GS after it sits for a couple days, I am noticing that the ls3 has a rocky start and revs high initially Then after 30 to 45 seconds, it calms down and idles smoothly.
This is a little less dramatic if I crank the engine before starting it. It does not set off any codes and runs fine once after the idle smooths out. The car only has 7700 miles. The Mobil 1 oil has been changed by the original owner on a regular basis. (I recently purchased the car. ) Is this normal or should I have cause for concern?
If this were any other car, I would think this condition would cause excessive engine wear.
This is a little less dramatic if I crank the engine before starting it. It does not set off any codes and runs fine once after the idle smooths out. The car only has 7700 miles. The Mobil 1 oil has been changed by the original owner on a regular basis. (I recently purchased the car. ) Is this normal or should I have cause for concern?
If this were any other car, I would think this condition would cause excessive engine wear.
Safety Car
Joined: May 2016
Posts: 4,662
Likes: 1,846
From: Erlanger, Kentucky
When starting my dry sump GS after it sits for a couple days, I am noticing that the ls3 has a rocky start and revs high initially Then after 30 to 45 seconds, it calms down and idles smoothly.
This is a little less dramatic if I crank the engine before starting it. It does not set off any codes and runs fine once after the idle smooths out. The car only has 7700 miles. The Mobil 1 oil has been changed by the original owner on a regular basis. (I recently purchased the car. ) Is this normal or should I have cause for concern?
If this were any other car, I would think this condition would cause excessive engine wear.
This is a little less dramatic if I crank the engine before starting it. It does not set off any codes and runs fine once after the idle smooths out. The car only has 7700 miles. The Mobil 1 oil has been changed by the original owner on a regular basis. (I recently purchased the car. ) Is this normal or should I have cause for concern?
If this were any other car, I would think this condition would cause excessive engine wear.
If not, maybe check the plugs and wires. And check to make sure everything is tight on the intake clamps. Not a bad idea to check the bolts holding the intake manifold to the engine. Basically, check for any air leaks as this can cause rough running.
Racer
Joined: Sep 2019
Posts: 296
Likes: 194
From: Northern MN
It probably wouldn't hurt to clean the MAF and put a bottle of Techron fuel system cleaner in your gas. But, it's most likely the open-loop fueling map at cold idle that's contributing to the lope, until the O2 sensors get up to operating temps when the ECM switches to closed-loop.
This condition is normal on my '09 LS3 and it sounds like I have a cam... wish I did!
This condition is normal on my '09 LS3 and it sounds like I have a cam... wish I did!
Thread Starter
Instructor
Joined: Jun 2021
Posts: 228
Likes: 95
From: Westminster, Maryland
Any codes or CEL's?
If not, maybe check the plugs and wires. And check to make sure everything is tight on the intake clamps. Not a bad idea to check the bolts holding the intake manifold to the engine. Basically, check for any air leaks as this can cause rough running.
If not, maybe check the plugs and wires. And check to make sure everything is tight on the intake clamps. Not a bad idea to check the bolts holding the intake manifold to the engine. Basically, check for any air leaks as this can cause rough running.
Thanks for the input!
Thread Starter
Instructor
Joined: Jun 2021
Posts: 228
Likes: 95
From: Westminster, Maryland
It probably wouldn't hurt to clean the MAF and put a bottle of Techron fuel system cleaner in your gas. But, it's most likely the open-loop fueling map at cold idle that's contributing to the lope, until the O2 sensors get up to operating temps when the ECM switches to closed-loop.
This condition is normal on my '09 LS3 and it sounds like I have a cam... wish I did!
This condition is normal on my '09 LS3 and it sounds like I have a cam... wish I did!
Safety Car
Joined: Sep 2007
Posts: 4,009
Likes: 491
From: South Florida
This could be normal, its just hard to determine without hearing the car in person. These cars have quite a bit of lope, especially on a cold start. My C5 had a somewhat aggressive idle, but the C6 is noticably more aggressive. No codes and issues with my car, was told by a bunch of people on here it was normal from day 1. Smooths right out (still a tiny chop as I call it) when the revs drop back down. I honestly wish these cars idled a smidge higher because its too damn quiet at idle.
Melting Slicks
Joined: Nov 2011
Posts: 3,183
Likes: 265
From: Virginia
This is exactly what my 2011 LS3 does. On a cold motor it revs high on initial startup and then stumbles a bit then evens out shortly… sounds a lot like a cammed car. I put new plugs and wires on recently and it still does it, have not tried cleaning the maf yet…sounds like this may be pretty common tho.
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