Misfire at idle, cyl #8

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

gpracer1

Full Access Member
Joined
Jun 16, 2011
Posts
910
Reaction score
362
Location
Phoenix
Truck has always run great. Got gas at Costco yesterday and as soon as I started it and got to the first stop sign, I could tell it was misfiring on some cylinders.....you could feel the twitch at idle. Runs ok normal driving. Took a look lunch break at work with the Tech 2.....live graph shows big time misses on #8. So now I think the gas at Costco was just a coincidence.....I will check the plugs when I get home...hopefully they aren't counterfeit iridiums from Amazon.
 

TollKeeper

Full Access Member
Joined
Feb 21, 2010
Posts
3,042
Reaction score
6,046
Location
Brighton, CO
Try running some HEAT gas dryer thru it. With all that rain you guys got, that is now coming into colorado, might just be some water.
 
OP
OP
gpracer1

gpracer1

Full Access Member
Joined
Jun 16, 2011
Posts
910
Reaction score
362
Location
Phoenix
After driving it to work 30 miles and hooking up the Tech 2, I found its only #8 cylinder so that probably rules out crappy gas. I also shut off that injector and then its a solid miss, not random 2-3 per second. Feels worse in gear at idle. Im guessing plug but will have to wait till I get home and cool it off.......of course it has to be #8.
 

Fless

Staff member
Super Moderator
Joined
Apr 2, 2017
Posts
11,856
Reaction score
24,114
Location
Elev 5,280
What if #8 was never changed along with the others? Just speculating.
 
OP
OP
gpracer1

gpracer1

Full Access Member
Joined
Jun 16, 2011
Posts
910
Reaction score
362
Location
Phoenix
What if #8 was never changed along with the others? Just speculating.
I do all my own work....replaced them in 2019 with iridiums. Just hoping its not the dreaded lifter or something.
 
OP
OP
gpracer1

gpracer1

Full Access Member
Joined
Jun 16, 2011
Posts
910
Reaction score
362
Location
Phoenix
Ok, missing more but mostly idle or light load. Got home and pulled plug 1 since it’s easy…….looks like legit NGK plug in good shape. Started to get worried and had a fan on #8 so I wouldn’t get burned checking it. Put my hand down there and my pinky bumped the wire and it fell off (or wasn’t really on) the plug!!
I can’t for the life of me figure out how it popped off after 3 years, but snapped it back on and purrs like a kitten. Holy crap, what a relief. Drama over.
 

juicedgsr95

Member
Joined
Jun 24, 2020
Posts
53
Reaction score
72
Location
North Carolina
Ok, missing more but mostly idle or light load. Got home and pulled plug 1 since it’s easy…….looks like legit NGK plug in good shape. Started to get worried and had a fan on #8 so I wouldn’t get burned checking it. Put my hand down there and my pinky bumped the wire and it fell off (or wasn’t really on) the plug!!
I can’t for the life of me figure out how it popped off after 3 years, but snapped it back on and purrs like a kitten. Holy crap, what a relief. Drama over.

The same thing happened to me, wire on plug 8 came loose. no Idea how but pushed it back in and made sure it was in there good and the misfire was gone.
 
Top