Dealer not honoring warranty work..2018 5.3 Yukon issues

[91RS]

I don’t know if I missed it or don’t remember but is this a 5.3L or 6.2L? What fuel grade are you using?

 

[smokey_mountain]

5.3L 6-speed. Exxon Mobil 1 Regular. Two dealers told me explicitly not to use Premium with 2018 5.3L engines. Hendrick and Thompson GMC both told me that. Top Tier but not Premium.

I don’t know if I missed it or don’t remember but is this a 5.3L or 6.2L? What fuel grade are you using?

 

[91RS]

It shouldn’t be needed with the 5.3L but it isn’t going to hurt anything. Run it down to empty and fill up with premium and see what happens.

 

[swathdiver]

It shouldn’t be needed with the 5.3L but it isn’t going to hurt anything. Run it down to empty and fill up with premium and see what happens.

I think he's on his first or second tank of premium.

 

[smokey_mountain]

I did 1 full tank of Premium and will try another tank of Exxon Premium on the way to/from VA this weekend. I will drive "hard". I will convince my wife to take the truck to the Blue Ridge Highway if it is not closed for winter, that will give valves some serious workout.

 

[smokey_mountain]

Here is the summary of everything that Medlin GMC checked. Hard to fault this dealer, they really tried based on this work order? What do you guys think?

 

[smokey_mountain]

I may need to ask for wisdom again...
I am reading that misfires in $06 monitor misfires should be zero. I only have OBD Fusion to read $06 but what is the tool that dealer would accept as evidence of misfires? What shall I buy to log misfires to present to the dealer? I posted above their results, they said zero misfires anywhere during dealer’s testing. I assume that OBD Fusion is wrong about $06 data in my truck. What is $06 monitor anyway? How is it possible that I see misfires and dealer does not?
$06 monitor in OBD Fusion shows misfires in cylinders during 40 min trip on a second tank of Exxon 93 Premium Synergy+

C1 - 7
C2 - 1
C3 - 10
C4 - 5
C5 - 2
C6 - 5
C7 - 4
C8 - 2

 

[swathdiver]

How is it possible that I see misfires and dealer does not?

Gm equipment may be ignoring "misfires" that lack a certain intensity or frequency, the knock sensors can detect vibrations and other things happening around the engine bay and classify them as misfires. Take a hammer and rap on your exhaust manifolds while monitoring the knock sensors and see what happens.

 

[smokey_mountain]

Thank you. Any recommendation what tool should I buy/rent to monitor and log my truck?

Gm equipment may be ignoring "misfires" that lack a certain intensity or frequency, the knock sensors can detect vibrations and other things happening around the engine bay and classify them as misfires. Take a hammer and rap on your exhaust manifolds while monitoring the knock sensors and see what happens.

 

[Doubeleive]

I may need to ask for wisdom again...
I am reading that misfires in $06 monitor misfires should be zero. I only have OBD Fusion to read $06 but what is the tool that dealer would accept as evidence of misfires? What shall I buy to log misfires to present to the dealer? I posted above their results, they said zero misfires anywhere during dealer’s testing. I assume that OBD Fusion is wrong about $06 data in my truck. What is $06 monitor anyway? How is it possible that I see misfires and dealer does not?
$06 monitor in OBD Fusion shows misfires in cylinders during 40 min trip on a second tank of Exxon 93 Premium Synergy+

C1 - 7
C2 - 1
C3 - 10
C4 - 5
C5 - 2
C6 - 5
C7 - 4
C8 - 2

if there were misfires the ecm/bcm would store them in history and after enough misfires were recorded it would display a check engine light, that's how it works. whatever is happening is not enough for the computer to say "hey something is wrong". The Dealer lever scanner for these trucks runs anywhere from $1500-4000.00 and yearly updates are generally anywhere from $500 to $1000, there are some sub $1000 scanners out there but not sure what they are capable of compared to the better ones. I have been working with a $120 china clone tool for my 2018 but haven't got it to work quit right yet with gds2 the software is hacked and it's just been a pia.