2021 Tahoe Misfire

[Btown Denali]

We have developed a misfire that so far the dealer cannot root cause.

Vehicle: 2021 Tahoe Premier 5.3L 26k miles owned for 2yrs

Problem: after cold start and driving 1/4 mile engine misfires then throws check engine flashing light. I will add that it does not sound like a dropped lifter.

1st time in dealership- 3 days- replaced injectors 1 &6

2nd time in dealership- 5 days-replaced injector 5

3rd time- 2 days- still pending

Any ideas or folks that have had similar issues?

 

[WalleyeMikeIII]

Wiring harness? Would think the dealer diags people would figure it out.
See Here:

https://static.nhtsa.gov/odi/tsbs/2021/MC-10205552-9999.pdf

 

[DuraYuk]

Find another dealer. Clearly they don't know what they are doing and souring your experience.

It's not medicine. Should be direct and concise not a guessing game.

 

[B-train]

Agreed ^^^^^. If there's no mechanical noise present, then it's either fuel or spark most likely. 1/4 mile of driving from a cold start means it's probably transitioning from open to closed loop. Fueling and spark/timing changes when that occurs.

 

[Btown Denali]

So its been at the dealer a month and even with GM tech guidance, they still cannot find root cause.

 

[DuraYuk]

So its been at the dealer a month and even with GM tech guidance, they still cannot find root cause.

New dealer time.

Bet it's a broken wire in the harness.

 

[pa31p]

they checked the coils for output ?
Coils can produce misfire, shudder, and sensations like a rumble.
particularly when the EGR is wide open. know what the code is ?

Flashing check engine light is a significant problem generally, like out of oil, surprised a misfire would throw that.

 

[DuraYuk]

they checked the coils for output ?
Coils can produce misfire, shudder, and sensations like a rumble.
particularly when the EGR is wide open. know what the code is ?

Flashing check engine light is a significant problem generally, like out of oil, surprised a misfire would throw that.

What are you surprised about ? A flashing check engine light is 99% of the time an active misfire. Sheesh.

 

[Btown Denali]

Update- contacted me and said they are replacing the drivers side bank of lifters. I am incredulous that this is the fix but perhaps.

 

[StephenPT]

In most cases it seems like the lifters fail at <10K miles, but not 100% of the time. Hopefully this is the fix your rig needs to get it back running as it should.