Why is my engine misfiring Morning it runs fine

Tiny
JASON SISTRUNK
  • MEMBER
  • 2014 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 193,683 MILES
On my truck listed above I can crank it in the morning it runs fine, I usually stop by a store around 10 minutes down the road. When I start the truck after leaving my engine light starts flashing and the stability light comes on. I can drive around 5 miles everything goes back normal. I've had it in the shop the scanner said misfire on # 2 they changed fuel injector coil plugs and wires it ran fine for a while now it's reading misfire on #5. Any help would be appreciated.
Tuesday, December 8th, 2020 AT 5:55 PM

17 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
Hi,

This guide should help us fix it it

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

There is a technical service bulletin (TSB) related to a misfire concern. It seems the spark plug wires retainers can come off and cause a misfire.

Since this TSB exists, I would recommend checking the number 7 spark plug wire. Take a look at the pic attached.

Let me know what you find.

Joe
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Tuesday, December 8th, 2020 AT 6:07 PM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
I just put new plugs and wires. I'll check #7 tomorrow and let you know. Thanks
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Tuesday, December 8th, 2020 AT 7:14 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
Hi,

Since it runs good cold and then you have a misfire after turning it off for a short time, I wonder if you have a leaking fuel injector. Once the pressure builds in the system, it could be leaking down into that cylinder.

Do me a favor. Here is a link that explains how in general to check fuel pressure. Do this and pay attention to how quickly the fuel pressure drops off when the key is turned off.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Let me know.

Joe

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Wednesday, December 9th, 2020 AT 8:37 PM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
Thanks. I haven't had time to check that. But my truck started doing something different. It's running a little worse and there is a chirping or squeaking sound coming from somewhere. And when I stop at a light my engine light goes off.
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Thursday, December 10th, 2020 AT 4:24 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
Does the chirping sound change with engine speed? Is it loud enough for you to record it and upload it for me to hear? Are there any new codes?

Let me know.
Joe
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Thursday, December 10th, 2020 AT 8:53 PM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
Yes, it gets loud when I go up a hill. Now it's saying a valve leak.
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Thursday, December 10th, 2020 AT 8:56 PM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
A valve leak on #1 and #2.
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Thursday, December 10th, 2020 AT 8:57 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Could the sound be coming from the transmission area? If not, we need to rescan the computer. There are several valves this could be referring to. I would scan the CAN system. CAN stands for controller area network. It ties all the modules/computers together. Here is a video:

https://youtu.be/InIlnsjOVFA

Still, record and upload the sound. With a little luck, I'll be able to recognize it. I'm starting to question if it is related to the cylinder deactivation system which can get involved.

Let me know
Joe
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Thursday, December 10th, 2020 AT 9:09 PM
Tiny
JASON SISTRUNK
  • MEMBER
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I will, thanks.
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Thursday, December 10th, 2020 AT 9:13 PM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
When I crank my truck this morning both lights came on and it sounded like my fan kicked on but it was something else.
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Friday, December 11th, 2020 AT 4:01 AM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
Flashing engine light and stability trak.
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Friday, December 11th, 2020 AT 4:03 AM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
It is shifting down hard.
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Friday, December 11th, 2020 AT 4:10 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Thanks for the videos. I listened but can't identify it over the computer. I was hoping I could. Do me a favor, we need to scan the CAN BUS to see how many codes are actually hidden that we don't know about.

Is that something you could have done?

Joe
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Friday, December 11th, 2020 AT 9:31 PM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
I went to Napa they scanned my computer the only code it was reading was misfire on #5. I changed the coil pack. Cleaned the o2 sensors and clamped that exhaust flapper open. I was just trying anything I could think of. So far the engine last stopped flashing no stability trak light its running pretty good still a little of a rough idle but it's way better, so I don't know what fixed it.
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Saturday, December 12th, 2020 AT 5:45 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
It could have been the coil you replaced. Let me know if things change.

Take care,
Joe
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Saturday, December 12th, 2020 AT 11:19 PM
Tiny
JASON SISTRUNK
  • MEMBER
  • 11 POSTS
Thanks, I hope so.
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Sunday, December 13th, 2020 AT 7:04 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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You are very welcome. Please feel free to come back anytime in the future. You are always welcome here.

Take care,

Joe
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Sunday, December 13th, 2020 AT 10:16 PM

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