2017 6.2L misfire (descriptive situation)

[Rfd2]

2017 Yukon 6.2L. Getting a p0300 code. Stabilitrak and light comes on when throttle is 1/2-3/4.

Originally I thought it might’ve been the torque converter shudder setting it off, so I changed the fluid regardless.
So far, I’ve checked the misfires with my computer. On cold startup, cylinder 6 has hundreds of misfires, as it warms up it will go away and only misfire on that cylinder.

Pulled the plug, looked fine. Not too much carbon or oil.

Did a compression test, all cylinders on bank 2 are getting the same reading. No ticks or knocks.

Put a new coil on just for fun, no changes.

Computer is saying there isn’t a misfire on any injectors. After doing a balance test, all injectors are between 30-35psi except for #6 which is around 55-65psi.

Am I missing something? Or does it sound like a bad injector? I’m only
Leaning towards that because the pressure is much higher than the other 7 cylinders, and that’s what’s confusing me. Should I try to see if the intake gasket is bad for that cylinder as well?

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You've done your pre-work on troubleshooting so far.

Do you have, or have access to, a quality bi-directional scanner? If not, I recommend that you get yourself a quality bi-directional scanner to add to your tool box. Then, you will be able to read ALL trouble codes, along with a brief explanation/pointer to the source of your issue. You can test many of the truck's electronic functions with the scanner, in order to determine the source of an issue. You will also be able to reset/delete trouble codes, after taking corrective action. You will literally save thousands of dollars in diagnostic and repair costs over the life of your truck, and you will most likely recoup the cost of the scanner within 1 year.

I suspect that you have additional trouble codes stored that would provide very valuable information regarding your issue.

Other members of this Forum much more knowledgeable than me in this area will chime in.

 

[Fless]

Replace the injector that is fueling way higher than the others, as indicated by the injector balance test. It's causing that bank to be in a state of imbalance. It's flowing too much fuel (relative to the other injectors) to that hole.

Please use an OE injector.

 

[Doubeleive]

2017 Yukon 6.2L. Getting a p0300 code. Stabilitrak and light comes on when throttle is 1/2-3/4.

Originally I thought it might’ve been the torque converter shudder setting it off, so I changed the fluid regardless.
So far, I’ve checked the misfires with my computer. On cold startup, cylinder 6 has hundreds of misfires, as it warms up it will go away and only misfire on that cylinder.

Pulled the plug, looked fine. Not too much carbon or oil.

Did a compression test, all cylinders on bank 2 are getting the same reading. No ticks or knocks.

Put a new coil on just for fun, no changes.

Computer is saying there isn’t a misfire on any injectors. After doing a balance test, all injectors are between 30-35psi except for #6 which is around 55-65psi.

Am I missing something? Or does it sound like a bad injector? I’m only
Leaning towards that because the pressure is much higher than the other 7 cylinders, and that’s what’s confusing me. Should I try to see if the intake gasket is bad for that cylinder as well?

most likely it is the injector based on your trouble shooting but swap plug/coil/wire around 1. at a time i.e. swap wire, then see if problem follows, then coil, then plug. just to rule it out.
the 2015, 2016, 2017 have troublesome injectors and there is a "special 10 year coverage" for some vin's, it might be worth the trouble to check with your dealer service department. if it is covered they will replace it or maybe all of them for free. In my case we had a couple bad ones and the dealer did them all but I am long time customer with them on good terms.
**edit did not read your entire post at first, I guess you can disregard swapping coil but plug should be swapped & wire just to rule it out

 

[Fless]

I think this is the one:

https://static.nhtsa.gov/odi/tsbs/2019/MC-10163854-9999.pdf