2017 GMC 5.3 Sierra Misfire

[Jeffc]

Hello, I’m new to the forum. I have a 2017 GMC Sierra 5.3 with 53k miles. I have a sporadic engine miss. I’ve had the fuel induction service and I’ve had all 8 fuel injectors replaced. However the miss continues periodically. I can drive it for 20 - 30 minutes without any issues, then out of the blue it starts to miss for several miles, then clear up again. It will run intermittently with the miss. When the fuel injectors were replaced, it was because the check engine light said that #7 cylinder had a miss. Further diagnostics indicated that the left bank injectors were all bad - so I had all 8 replaced, playing it safe. But now with this latest miss there’s no check engine light. It occurs when the truck is at operating temperature. Without the check engine light on, no one can diagnose it, especially the guys who replaced to fuel injectors. I’ve been fighting this since late December. Does anyone have an idea of what my problem may be? I have not replaced the spark plugs, wire or coils - too much money ($1500 est. for all three items) and I’m over $3k into it now. If I was sure that would fix it, I would have them replaced. Thanks in advance for any input you can provide.

 

[zora]

Does the miss seem the same as the prior miss?
What is the part number of the new injectors and manufacturer?

 

[Jeffc]

yes, the miss seams almost the same, except no check engine light now. I'll have to get the part number and manufacturer name from the repair shop. Thanks for responding.

 

[Jeffc]

Talked to the repair place and the parts are AC Delco #12710481

 

[Sal Collaziano]

Lots of good information here as well:

GMC Sierra Forum

Forum for discussions regarding the GMC Sierra

gmcowners.com

 

[zora]

Talked to the repair place and the parts are AC Delco #12710481

Did the shop check technical service bulletins, there appear to be some concerning your problem.

 

[Jeffc]

Thanks...I posted there as well.

 

[Jeffc]

not sure if they checked technical bulletins. Can I personally check? Is there a bulletin number you can share? Thanks!

 

[zora]

not sure if they checked technical bulletins. Can I personally check? Is there a bulletin number you can share? Thanks!

For details on TSB's a subscription is needed which the shop should have.

 

[Jeffc]

okay, thanks!

 

[Jeffc]

Heard from my repair shop and they have indicated that they were finally able to get my truck to miss while the scanner was connected. Cylinder #7 misfired and it was traced to the coil. They switched the coil with cylinder #5 and the miss followed the coil to #5. So, sounds like my problem was the #7 coil. We will find out for sure when I put miles on it. I hope this will help anyone with this same problem in the future.