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2021 Silverado 6.2 rough idle ?


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Bought my truck brand new with 5 miles on it.  I mentioned it to the dealer when I test drove it.  He told me they "all do it".  26k miles later and it stills does it, but I'm not worried about it because if it was something to worry about, it should have gotten worse over the miles and it hasn't changed a bit.  I live in California, so 91 octane is all we get.  may give the Amsoil stuff a try and see how it goes. 

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Disabled by the actual Pulsar LT or the Range AFM/DFM disabler? The AFM/DFM doesn't work on the 2019+ 10 speed trucks per their website: The AFM/DFM Disabler is NOT currently compatible with 2019+ 5.3L 10-speed or 6.2L 10-speed models.

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I had the same question on my 6.2. Was about to run a “cleaner” through but checked fuel trims to see if injectors were dirty, after 40k miles, they’re nearly perfect…. So unless there’s some other fuel related issue, they probably just idle a little rough.

 

fwiw, my afm is disabled 

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On 10/9/2021 at 7:09 AM, lpg said:

I had the same question on my 6.2. Was about to run a “cleaner” through but checked fuel trims to see if injectors were dirty, after 40k miles, they’re nearly perfect…. So unless there’s some other fuel related issue, they probably just idle a little rough.

 

fwiw, my afm is disabled 

Ok thank you I might try some of that amsoil fuel treatment and see if that helps 

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On 10/12/2021 at 8:29 PM, Rcfire said:

Ok thank you I might try some of that amsoil fuel treatment and see if that helps 

My point in writing was that the motor is running perfect if fuel trim is near zero.

 

not sure what may be causing idle to seem rough but I don’t think there’s any problems or any fuel related system to be cleaned. 

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22 hours ago, lpg said:

My point in writing was that the motor is running perfect if fuel trim is near zero.

 

not sure what may be causing idle to seem rough but I don’t think there’s any problems or any fuel related system to be cleaned. 

So I looked further into it and seems mine is the motor mounts.  I found a service bulletin out for it and says they are either faulty or need shims.  Taking it in Monday and I’ll keep everyone posted 

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Motor mounts don't help.  I had to show the dealer that the truck had rough idle when in gear.  They were observing in Park and it ran smooth.  Traded the day after motor mounts didn't fix it.  2018 GMC 5.3L 8peed 4wd.  Did the rough idle from 300 miles on.  They wanted me to pay to have the fuel system cleaned at 35900 miles.  I explained it was doing the rough idle on the first tank of fuel.

 

Currently have 2021 GMC with 3.0 duramax.  I have had enough of the GM gas engines. This one doesn't always start on the first try, but runs smooth as silk when its running.

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11 hours ago, start2finish said:

Motor mounts don't help.  I had to show the dealer that the truck had rough idle when in gear.  They were observing in Park and it ran smooth.  Traded the day after motor mounts didn't fix it.  2018 GMC 5.3L 8peed 4wd.  Did the rough idle from 300 miles on.  They wanted me to pay to have the fuel system cleaned at 35900 miles.  I explained it was doing the rough idle on the first tank of fuel.

 

Currently have 2021 GMC with 3.0 duramax.  I have had enough of the GM gas engines. This one doesn't always start on the first try, but runs smooth as silk when its running.

12 hours ago, start2finish said:

Motor mounts don't help.  I had to show the dealer that the truck had rough idle when in gear.  They were observing in Park and it ran smooth.  Traded the day after motor mounts didn't fix it.  2018 GMC 5.3L 8peed 4wd.  Did the rough idle from 300 miles on.  They wanted me to pay to have the fuel system cleaned at 35900 miles.  I explained it was doing the rough idle on the first tank of fuel.

 

Currently have 2021 GMC with 3.0 duramax.  I have had enough of the GM gas engines. This one doesn't always start on the first try, but runs smooth as silk when its running.

Did you have your motors mounts replaced ? And it didn’t help ? Ugh so frustrating.  Mine vibrates so bad when in park and in drive.  On the highways it’s smooth 

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On 10/17/2021 at 8:40 AM, Rcfire said:

 

yes, they replaced the motor mounts.  No difference.  Treating a symptom of the skip doesn't fix the problem.  I believe its a known issue that they don't consider to be a problem.  It was embarrassing when passengers noticed it.  Only issue that truck ever had, I was happy with it overall.  But I am glad its gone.

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  • 2 weeks later...

I'm on my 3rd 6.2 since 08, this one is the smoothest (21 6.2) with foot on brake, but still has a little shake from time to time.  When I was getting the 08 tuned Justin mentioned to me that the truck is idling at some stupid low RPM and like lpg mentioned adding a little RPM will smooth it right out.  He added a little to show me and then went super smooth, but then set back to stock range.  If you leave the stupid stop/start on less shake time haha.

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  • 3 weeks later...

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