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I've had this issue for two months but it has been minimal until recently. While going anywhere above 30mph, at around 1200rpm if I give it about quarter throttle to half throttle i will hear a clanking/knocking noise. I have recorded it with my phone but you are unable to hear it at all. The other day while merging on the highway it made the noise much worse than it ever has. I am wondering if anyone has had this before, I know some of the 3.0 DuraMax guys have had it, but has anyone with the 6.2 had an issue similar to this. I will be taking it to the dealership tomorrow.
By Steve Polzien
Hey everyone, I recently purchased a 2017 GMC Sierra 1500. It’s a 4x4 Denali with the 6.2L and ultimate package. Overall it’s everything I’ve ever wanted in a truck and more.
I live and work in South Carolina, but I’m originally from Upper Michigan (Yooper, eh). Husband to an amazing wife and father to two busy boys.
I joined the forum to get some insight into maintaining my truck as well as some tips for upgrading smaller items.
So I've tuned my truck with and it has made a difference from what I can tell. A couple of questions, however.
1. Is there any way to truly fix the hard downshift from 3-2 and what I call lagging going from 2-3 under acceleration? I installed the 91 octane tune, disabled AFM, speed limiter and changed the shift points from 2-3. It seems like the shift point pressure is too much. The RPM's spike when i'm easy on the throttle after a stop.
2. There is an option to change the axle ratio via the tuner which I thought was impossible because the axle is ratio is mechanically fixed, yes? I think I have the 3.23 but I am not 100% sure
3. Side note, I have an Air Raid intake tube, k&n filter, installed a catch can and did a muffler delete. I took out the flapper valve out as well. Truck runs and performs better (sounds awesome too). When I go to pass cars on the highway, I can easily break 100 and you can tell the engine still has a lot left. I truly believe that this truck's engine life has been extended greatly after disabling AFM. Thanks guys.
By Jarid Ashman
Alright, before you say you don’t hear anything let me explain first. This video posted below is my 2021 Trail Boss 3500k miles and has the most annoying exhaust sound. I know there’s some serious pro’s on here who could tell me what’s going on.
Essentially any time I start it up high RPM, accelerate, or decrease RPM’s I’m greeted with this annoying metallic rattling noise coming from exhaust.
Took it to dealer who claims it’s normal (per-usual) and says it’s the liters I can hear in the exhaust tone. They checked exhaust donuts and heat shields and found no issue.
However you can hear a rattle and what sounds like an exhaust leak. Was told it’s a flapper but it’s not, flapper is toward back passenger side. This is front passenger side.
I could best describe it as escaping air coming from somewhere near the manifold I’d assume. Almost like a metallic farting exhaust noise for lack of better description.
Videos to follow of noise while commuting.
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