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Engine Revs to Redline on Cold Start 6.2L

Denny NWO
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Denny NWO Enthusiast

Denny NWO

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The dealer called me today and said to bring it in tomorrow and they are going to install a new ECM. Hopefully this works.

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Denny NWO
Denny NWO

It's been a week with the monitor connected to the OBDII and connected live with GM TAC and my truck has not revved to 3500RPM but has coughed and fluttered upon starting but it recovers immediately.

Denny NWO
Denny NWO

My truck went to the dealership on Tuesday and GM gave me a rental to drive for the week while the tech took my truck home. It started normal the first few days but acted up Friday morning when he sta

SPASierra
SPASierra

Right, but even drive by wire TPS sensors are essentially a potentiometer that sends a voltage based on position of the throttle plate.   None of this is likely to be the cause of his issue, but the

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Denny NWO Enthusiast

Denny NWO

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16 hours ago, Chebby said:

Did that fix it?

No it did not. It seemed to start normal for a few days after but it is still randomly starting and revving to 3500RPM. Service manager is talking to GM and they are going to give me a rental and take my truck until they figure out the issue.

Whiskeyranch Enthusiast

Whiskeyranch

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Damn now I’m regretting buying the 6.2. Mine at the dealer for the valve springs after having it break down in me after 16 hours of ownership. Hope they get it sorted for ya. Mine will be parked outside as well and it gets below freezing a lot in CO.

  • 2 weeks later...
Denny NWO Enthusiast

Denny NWO

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My truck went to the dealership on Tuesday and GM gave me a rental to drive for the week while the tech took my truck home. It started normal the first few days but acted up Friday morning when he started it. Instead of revving to 3500RPM, the engine started then fluttered and stalled. He managed to record the event through the OBD Live Capture diagnostic reader and they now have something to work with. They called me to pick up my truck and the service manager told me that GM TAC is now looking into the cause and they have made it a priority. He also told me that another customer reported the same issue with their truck so I'm not the only one.

I will let everyone know what the outcome is once they figure it out.

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Denny NWO Enthusiast

Denny NWO

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Received a call from the service manager last week who told me GM Technical Assistance Centre was sending a Field Representative here to look into the issue with my truck. He then called me back a few hours later and said that they want to install a live link black box that will stream ECM diagnostic information over the cellular network. They have shipped the box here and in the meantime, i took my truck to the dealer to have the wiring connection installed so they can connect the box quickly once it arrives at the dealers service center this week. 

mafd2 Senior Enthusiast

mafd2

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Thanks for the update; keep us posted. I hope the black box tells them something. And no other member on the forum has had this issue?

Edited by mafd2
redwngr Senior Enthusiast

redwngr

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Continues to be quite a saga.  

 

Really hope they find a cause, and release the info, so we know what caused the issue.

Rob Mugs Enthusiast

Rob Mugs

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9 hours ago, Denny NWO said:

Received a call from the service manager last week who told me GM Technical Assistance Centre was sending a Field Representative here to look into the issue with my truck. He then called me back a few hours later and said that they want to install a live link black box that will stream ECM diagnostic information over the cellular network. They have shipped the box here and in the meantime, i took my truck to the dealer to have the wiring connection installed so they can connect the box quickly once it arrives at the dealers service center this week. 

That's fantastic!  For once, technology is actually helping diagnostics.  Didn't even know this was a thing

Chebby Enthusiast

Chebby

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On 1/17/2021 at 11:55 AM, Denny NWO said:

Received a call from the service manager last week who told me GM Technical Assistance Centre was sending a Field Representative here to look into the issue with my truck. He then called me back a few hours later and said that they want to install a live link black box that will stream ECM diagnostic information over the cellular network. They have shipped the box here and in the meantime, i took my truck to the dealer to have the wiring connection installed so they can connect the box quickly once it arrives at the dealers service center this week. 

Two months later, they want to stream ECM diagnostics. Sorry you’re still dealing with this.

  • 2 weeks later...
Denny NWO Enthusiast

Denny NWO

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So I took the truck to the dealer on Friday and had the box installed. It is connected to the OBDII port and sitting under the drivers seat and a black cord with a red button is sitting in my cup holders. I was told to press the button if it acts up when i start it. I parked the truck outside at home with overnight temperature at 5F ( -15C) I started it Saturday morning and it went to redline for 4 seconds and settled to idle. I did press the button as told. Sunday and Monday mornings, the truck started and fluttered but quickly recovered. I called the tech and provided the times so he could look it up on the live stream data logger. I was told to keep logging and they would contact me when they have the information.

 

I was also told that 5 other customers have reported the same issue to this dealer so this could be bigger than first thought. I don't mind being the guinea pig or lab rat if this will help others.

 

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Denny NWO Enthusiast

Denny NWO

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Update today: My truck keeps asking me to install an update every time I shut it off today. Called the service manager and asked him if I should do the update, he said to ignore it. He called me a few hours later and told me the box is not communicating with GM TAC and now a have to drop it off at the dealer again tomorrow morning. When I got home tonight, I shut the truck off and opened the door and got out, but the radio stayed on. I went back out 8 minutes later and it was still on. The FOB was in the house so I got it and went back out, reached in and pressed the start button (without the brake) and pressed it again and it finally went off.

BigMick2023 Enthusiast

BigMick2023

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Posted (edited)
On 2/1/2021 at 7:59 PM, Denny NWO said:

So I took the truck to the dealer on Friday and had the box installed. It is connected to the OBDII port and sitting under the drivers seat and a black cord with a red button is sitting in my cup holders. I was told to press the button if it acts up when i start it. I parked the truck outside at home with overnight temperature at 5F ( -15C) I started it Saturday morning and it went to redline for 4 seconds and settled to idle. I did press the button as told. Sunday and Monday mornings, the truck started and fluttered but quickly recovered. I called the tech and provided the times so he could look it up on the live stream data logger. I was told to keep logging and they would contact me when they have the information.

 

I was also told that 5 other customers have reported the same issue to this dealer so this could be bigger than first thought. I don't mind being the guinea pig or lab rat if this will help others.

 

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Such a clean install.....  ?

 

So by the time they finally figure something out, just how much engine damage has occurred by then? High revs on a cold engine can’t be a good thing. 

Edited by BigMick2020
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Denny NWO Enthusiast

Denny NWO

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Update: I got a call on Tuesday afternoon from the dealer, apparently the box wasn't communicating with GM TAC. Dropped the truck off Wednesday morning and they gave me a new loaner to drive, then I received a call at the end of the day that they were still working on the issues and needed to keep it. Got another call Thursday at noon, GM TAC is shipping a new data box so I picked up my truck and will have to bring it back next week. I did find out that this issue is specific to the 6.2L engine only and they now have 6 other 6.2L owners experiencing the same issues. Stand by.

 

So by the time they finally figure something out, just how much engine damage has occurred by then? High revs on a cold engine can’t be a good thing. 

Edited Tuesday at 09:24 PM by BigMick2020

 

Yes BigMick2020 -  I'm definitely concerned about engine damage when the truck goes to 3500RPM for 10 seconds from a Cold Start. Engine oil is not pumping very well at -29F which is the forecasted overnight low this weekend.

Edited by Denny NWO
Rob Mugs Enthusiast

Rob Mugs

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50 minutes ago, Denny NWO said:

 

Yes BigMick2020 -  I'm definitely concerned about engine damage when the truck goes to 3500RPM for 10 seconds from a Cold Start. Engine oil is not pumping very well at -29F which is the forecasted overnight low this weekend.

Don't worry, it won't break until you hit 60,001 miles

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