Replaced plugs and wires at 76k - 2015 Denali

[SuperOldSchool]

Hello

Sharing pics of plugs at 76k. Changed wires as well.

Manual states 97,500 miles to do this, but I tend to do routine maintenance early, since I don’t drive in ideal conditions. Waiting until 100k might also make it hard to get plugs out...

They look great. Probably no issues going the full 100k interval.

Rebate going on now for AC Delco 41-114 $3 back per plug. So, from Amazon they end up only $3.39 each.

 

[BMPNUGLS]

They do look pretty clean! Any noticeable difference in performance/mileage etc from the change? I’d be more curious if you found any defects in the wires due to age etc...

 

[SuperOldSchool]

I can’t really tell a difference. Maybe a little smoother idle, but I thought that could be placebo effect.

Wires looked fine and I resistance tested one and it was fine.

I really just figured:

1- we don’t drive in ideal textbook conditions, so 100k seems long

2- the longer those plugs stay in there, the harder they can be to remove

3- I’ll never have to do it again, since the longest I’ll keep the truck is to 150-200k (I hope, if it doesn’t fall apart before then)

 

[SuperOldSchool]

I take it back about not noticing a difference - idle is smoother now. Used to kinda pulse or shake a little sometimes and that’s gone now.
Maybe it was time in fact....

 

[Bob2C]

I take it back about not noticing a difference - idle is smoother now. Used to kinda pulse or shake a little sometimes and that’s gone now.
Maybe it was time in fact....

Was your idle smooth when new and got rough? I have a slight shake at idle and now wondering if plugs have something to do with it. I have 9k miles on the truck and its been a slight bumb at idle, almost like a misfire. Dealer says normal..(of course)

 

[BMPNUGLS]

Was your idle smooth when new and got rough? I have a slight shake at idle and now wondering if plugs have something to do with it. I have 9k miles on the truck and its been a slight bumb at idle, almost like a misfire. Dealer says normal..(of course)

Try running some SeaFoam and/or Marvel Mystery Oil (see both labels for mixing) with a couple consecutive Premium (93oct) fill ups....doing this every 6-10K miles does wonders for my 6.2 Denali XL. I also spray down the MAF sensor w the proper cleaner (auto parts store) on about the same intervals...

Both my 2015 Suburban and the 2016 Denali seemed to have a rough and/or low idle to me when they were new...but since doing the above they both idle extremely smooth.

Or try this concoction - several people I know mix up this ‘cocktail’ and SWEAR by it!!

 

[Bob2C]

Thanks for the info

 

[gat0r]

re:rough idle... i had a rough idle , but thought it was due to being too low.
in my tune, i had BBP raise up 100 rpm. so it went from 500 to 600 rpm & its nice & smooth now

 

[Bob2C]

re:rough idle... i had a rough idle , but thought it was due to being too low.
in my tune, i had BBP raise up 100 rpm. so it went from 500 to 600 rpm & its nice & smooth now

Mine actually idles when warm below 500. Maybe 450 I am thinking.

 

[SuperOldSchool]

Was your idle smooth when new and got rough? I have a slight shake at idle and now wondering if plugs have something to do with it. I have 9k miles on the truck and its been a slight bumb at idle, almost like a misfire. Dealer says normal..(of course)

It was sometimes a little rough or bumpy when new. Dealer said it was normal and then it actually seemed to smooth out after a while.

I did run Techron cleaner several times over last few years.

I guess it must have creeped back a bit, because it’s really smooth now.