2020 Suburban Premier w/ 250,000 miles. 11,500$

[olyelr]

….the 6.2L is awesome but paying for premium and getting 12mpg is not fun.

Huh. We put 125k miles on my wifes 2016 denali xl before trading it in and never once stuck a tank of premium in it. Just regular. Always average around 20mpg.

 

[LSCALADE]

I got to 254k miles and decided it's time to swap the spark plugs. All was good for a few days, and out of nowhere I started getting CYL 7 misfire, and my mind immediately went to a lifter issue, but then I heard the spark arc across to something else, and went to check the plug wire, and sure enough it was not seated all the way down. Misfire gone now. The engine seems to run smoother after the sparkplug change. The plug wires had to have been at least 150k miles since they were super brittle.

 

[89Suburban]

I got to 254k miles and decided it's time to swap the spark plugs. All was good for a few days, and out of nowhere I started getting CYL 7 misfire, and my mind immediately went to a lifter issue, but then I heard the spark arc across to something else, and went to check the plug wire, and sure enough it was not seated all the way down. Misfire gone now. The engine seems to run smoother after the sparkplug change. The plug wires had to have been at least 150k miles since they were super brittle.

Phew!

 

[k_arnold72]

I got to 254k miles and decided it's time to swap the spark plugs. All was good for a few days, and out of nowhere I started getting CYL 7 misfire, and my mind immediately went to a lifter issue, but then I heard the spark arc across to something else, and went to check the plug wire, and sure enough it was not seated all the way down. Misfire gone now. The engine seems to run smoother after the sparkplug change. The plug wires had to have been at least 150k miles since they were super brittle.

Which plugs you go with?

 

[LSCALADE]

Which plugs you go with?

NGK Plugs and factory AC Delco wires from Rockauto. It had GM plugs in it and Carfax said they were changed around 209k miles. The wires were suspect since they came apart when I pulled them out and I suspect they were old maybe original. Plugs on the other hand looked fine but I am trying to do a STAGE 0 reset on the truck all new fluids and tune up and then push it to the 400k mile mark.

I need to get some help with a tune since I have a larger intake now and a 3" exhaust and I am sure the MAF and VE can be tweaked some, but I am not brave enough to make the changes myself.