New issue
Thread Starter
1st Gear
Joined: Mar 2025
Posts: 1
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New issue
Greeting folks,
Please help or direct me to a post that will address this issue.
The Car: 2017 C7 13,000 miles
This car sat for 3 years not driven. It was purchased brand new in 2017, driven for 4 years then parked for 3 years before being rescued this year.
When it was collected this year after sitting, it was towed to a dealer where it got a new battery and oil change, then driven 800 miles to its new destination.
The only thing of note, from its original origin this year to the new destination 800 miles away is that the rpm noticeably would fluctuate by 100-200 rpm while keeping even speed on a flat road. This still occurs.
I just seems odd to see the needle fluctuate without changing the acceleration or decelerating.
The new issue of concern:
In auto, when driving between 1300 and 1500 rpm’s the car fluctuates from V4 to V8. No different than lower speeds and gears but, when you slowly accelerate, at 1300-1500 rpm’s, in 6 or 7th gear about 35 to 45 mph there is a rattle that sounds like it’s from the engine compartment. The sound is like a thin piece of steel smacking against something. Not terribly load but very obvious. We also experience a slight jitter/rumble which is physically felt. It feels like you’re driving on a road with tiny bumps. Both the rumble and rattle are intermittent. These two symptoms have been felt at higher speeds 60-70mph while in cruise control as well.
something of note, neither thing happens while in manual.
Thank you very much for your guidance and feedback
Please help or direct me to a post that will address this issue.
The Car: 2017 C7 13,000 miles
This car sat for 3 years not driven. It was purchased brand new in 2017, driven for 4 years then parked for 3 years before being rescued this year.
When it was collected this year after sitting, it was towed to a dealer where it got a new battery and oil change, then driven 800 miles to its new destination.
The only thing of note, from its original origin this year to the new destination 800 miles away is that the rpm noticeably would fluctuate by 100-200 rpm while keeping even speed on a flat road. This still occurs.
I just seems odd to see the needle fluctuate without changing the acceleration or decelerating.
The new issue of concern:
In auto, when driving between 1300 and 1500 rpm’s the car fluctuates from V4 to V8. No different than lower speeds and gears but, when you slowly accelerate, at 1300-1500 rpm’s, in 6 or 7th gear about 35 to 45 mph there is a rattle that sounds like it’s from the engine compartment. The sound is like a thin piece of steel smacking against something. Not terribly load but very obvious. We also experience a slight jitter/rumble which is physically felt. It feels like you’re driving on a road with tiny bumps. Both the rumble and rattle are intermittent. These two symptoms have been felt at higher speeds 60-70mph while in cruise control as well.
something of note, neither thing happens while in manual.
Thank you very much for your guidance and feedback
Administrator
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Cruiser
Joined: Sep 2021
Posts: 491
Likes: 597
From: NE Ohio
2025 C7 of the Year Finalist - Modified
2024 C7 of the Year Finalist - Modified
Greeting folks,
Please help or direct me to a post that will address this issue.
The Car: 2017 C7 13,000 miles
This car sat for 3 years not driven. It was purchased brand new in 2017, driven for 4 years then parked for 3 years before being rescued this year.
When it was collected this year after sitting, it was towed to a dealer where it got a new battery and oil change, then driven 800 miles to its new destination.
The only thing of note, from its original origin this year to the new destination 800 miles away is that the rpm noticeably would fluctuate by 100-200 rpm while keeping even speed on a flat road. This still occurs.
I just seems odd to see the needle fluctuate without changing the acceleration or decelerating.
The new issue of concern:
In auto, when driving between 1300 and 1500 rpm’s the car fluctuates from V4 to V8. No different than lower speeds and gears but, when you slowly accelerate, at 1300-1500 rpm’s, in 6 or 7th gear about 35 to 45 mph there is a rattle that sounds like it’s from the engine compartment. The sound is like a thin piece of steel smacking against something. Not terribly load but very obvious. We also experience a slight jitter/rumble which is physically felt. It feels like you’re driving on a road with tiny bumps. Both the rumble and rattle are intermittent. These two symptoms have been felt at higher speeds 60-70mph while in cruise control as well.
something of note, neither thing happens while in manual.
Thank you very much for your guidance and feedback
Please help or direct me to a post that will address this issue.
The Car: 2017 C7 13,000 miles
This car sat for 3 years not driven. It was purchased brand new in 2017, driven for 4 years then parked for 3 years before being rescued this year.
When it was collected this year after sitting, it was towed to a dealer where it got a new battery and oil change, then driven 800 miles to its new destination.
The only thing of note, from its original origin this year to the new destination 800 miles away is that the rpm noticeably would fluctuate by 100-200 rpm while keeping even speed on a flat road. This still occurs.
I just seems odd to see the needle fluctuate without changing the acceleration or decelerating.
The new issue of concern:
In auto, when driving between 1300 and 1500 rpm’s the car fluctuates from V4 to V8. No different than lower speeds and gears but, when you slowly accelerate, at 1300-1500 rpm’s, in 6 or 7th gear about 35 to 45 mph there is a rattle that sounds like it’s from the engine compartment. The sound is like a thin piece of steel smacking against something. Not terribly load but very obvious. We also experience a slight jitter/rumble which is physically felt. It feels like you’re driving on a road with tiny bumps. Both the rumble and rattle are intermittent. These two symptoms have been felt at higher speeds 60-70mph while in cruise control as well.
something of note, neither thing happens while in manual.
Thank you very much for your guidance and feedback
Burning Brakes
Joined: Nov 2022
Posts: 910
Likes: 430
From: MN
Race Director
Joined: Mar 2010
Posts: 15,992
Likes: 820
Appreciate you sharing these concerns with your 2017 C7. Having it sit for a couple of years, it is always recommended it be looked at by a dealership before taking it on a long trip. This includes the RPM fluctuation that is occurring on the highway. If you need assistance locating a different dealer in the area, feel free to email our support team at socialmedia@gm.com. Just please be sure to include your Username and Forum title in the subject line.
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