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Key Lesson Learned When Changing My Spark Plugs

WPGB1977

Member
Supporting Member
Joined
Jul 9, 2017
Messages
49
Location
North Carolina, United States
I'm honestly not very mechanically inclined, and part of the reason that I bought my TJ was to learn how to work on it. With all of the forum info and youtube videos, plus how relatively easy they are supposed to be to work on, I thought it would be a great place to start.

Ever since I bought my Jeep a few weeks ago I've noticed that there's some hesitation under certain acceleration conditions. A little research revealed that it could be related to the spark plugs.

Watched the video at
and everything seemed straightforward. So...figured this would be a great place to start learning how to self-service my Jeep.

Went to the dealer, bought the OEM recommended plugs and followed the steps in the video....but made a critical mistake. I assumed that the gaps in the plugs would be spot on given that they were brand new and no damage to the boxes so I skipped the part where I was supposed to confirm the proper gap.

After completing the job, the acceleration was improved and all was well for about 20 minutes when I noticed a little jumpiness in the lower RPM range. Then....check engine light. S**t.

I knew it was related to the plugs so I went back and retorqued everything. Problem was still there.

Brought it to my local Firestone (not a huge fan of this place but it's really close and I've used them before so they know me) this morning to have the code read and problem diagnosed.

Long story short...the gap in the plug in cylinder 5 was incorrect. I KNEW I should have bought the little disc to measure it, but I ASSUMED that it was good to go (which we all know what can happen when you assume...).

So. Key lesson learned: follow ALL of the steps outlined when working on things on my Jeep....and assume nothing.

By the way, I'm uploading a pic of the old plugs. Thinking they're the originals. And yes, I snapped 3 of them which sucked until I realized it wasn't a huge deal. But I definitely was super careful with the new plugs when I put them in.

image.jpeg
 
OP
WPGB1977

WPGB1977

Member
Supporting Member
Joined
Jul 9, 2017
Messages
49
Location
North Carolina, United States
How did they snap?
I failed to keep the spark plug socket straight on them when removing them and when the socket exerted pressure on the side they snapped with ease. Not sure whether or not that was due to age or my being new at this, but in either case I was able to get them out using the spark plug socket even after they broke.

Like I said, it sucked for a few seconds because I thought they might have been stuck...thankfully that wasn't the case.
 

Mike_H

Off-Camber is scary
Supporting Member
Joined
Feb 28, 2017
Messages
9,246
Location
Grand Rapids, MI, United States
Yup, those were worn..This was what was in mine when I got her...I'm SURE they'd never been changed...In 126,000 miles! I was happy to see they were a nice lite brown. Means the air/Fuel ratio is right. Yours look decent too.

FqVTcIHTpJ4rgBqu7extD30E7OR9dTcbNuYnpaYrWn3AuWymoQSs3E4IaBJ4-weoAiZ470n5QV7FW7Fktbg=w348-h618-no.jpg
 

Jerry Bransford

TJ Guru Moderator
Staff Member
Supporting Member
Joined
Nov 9, 2015
Messages
24,779
Location
Fleming Island Florida
I failed to keep the spark plug socket straight on them when removing them
Ha I did that on 6 or 7 of the 8 plugs of my dad's Oldsmobile when I was about 14 and begged him to let me change his spark plugs. Amazingly he didn't say a word, he just bought more spark plugs and I got those in ok.[/QUOTE]
 
OP
WPGB1977

WPGB1977

Member
Supporting Member
Joined
Jul 9, 2017
Messages
49
Location
North Carolina, United States
Ha I did that on 6 or 7 of the 8 plugs of my dad's Oldsmobile when I was about 14 and begged him to let me change his spark plugs. Amazingly he didn't say a word, he just bought more spark plugs and I got those in ok.
[/QUOTE]
Lol...I had like a split second of terror when the first one snapped but kept my cool and went back after it. So relieved when it kept coming out....
 

JamesAndTheSahara

TJ Addict
Supporting Member
Joined
May 22, 2017
Messages
2,164
Location
Auburn, AL, United States
I'm honestly not very mechanically inclined, and part of the reason that I bought my TJ was to learn how to work on it. With all of the forum info and youtube videos, plus how relatively easy they are supposed to be to work on, I thought it would be a great place to start.

Ever since I bought my Jeep a few weeks ago I've noticed that there's some hesitation under certain acceleration conditions. A little research revealed that it could be related to the spark plugs.

Watched the video at
and everything seemed straightforward. So...figured this would be a great place to start learning how to self-service my Jeep.

Went to the dealer, bought the OEM recommended plugs and followed the steps in the video....but made a critical mistake. I assumed that the gaps in the plugs would be spot on given that they were brand new and no damage to the boxes so I skipped the part where I was supposed to confirm the proper gap.

After completing the job, the acceleration was improved and all was well for about 20 minutes when I noticed a little jumpiness in the lower RPM range. Then....check engine light. S**t.

I knew it was related to the plugs so I went back and retorqued everything. Problem was still there.

Brought it to my local Firestone (not a huge fan of this place but it's really close and I've used them before so they know me) this morning to have the code read and problem diagnosed.

Long story short...the gap in the plug in cylinder 5 was incorrect. I KNEW I should have bought the little disc to measure it, but I ASSUMED that it was good to go (which we all know what can happen when you assume...).

So. Key lesson learned: follow ALL of the steps outlined when working on things on my Jeep....and assume nothing.

By the way, I'm uploading a pic of the old plugs. Thinking they're the originals. And yes, I snapped 3 of them which sucked until I realized it wasn't a huge deal. But I definitely was super careful with the new plugs when I put them in.

View attachment 19662

Get a quality feeler to measure or wire spark plug gauge. Much better for adjusting gap (At least when working across multiple vehicles that use NGK stock, unlike my TJ)! Local ACE had a wire spark plug gauge thats still made in the USA for $2.79. http://www.acehardware.com/product/index.jsp?productId=35608216&cp=2568443.2568455.2629358.1259023
 

FF_Jeep

TJ Enthusiast
Supporting Member
Joined
Dec 31, 2016
Messages
484
Location
Nashville, TN, United States
Been there! Snapping them off will scare the hell out of you if you've never done it before. I had to re tap a spark plug hole once on an old S-10 of mine. Not fun.


Sent from my iPad using Tapatalk
 
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JP98

TJ Addict
Supporting Member
Joined
Nov 3, 2016
Messages
1,477
Location
GA, United States
As easy as changing plugs is, we all have a story of jacking something up at some point. It's how you learn. It sounds like you have the right attitude for owning a TJ. Keep turn those wrenches and busting knuckles.
 
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Marklar1983

New Member
Supporting Member
Joined
Apr 11, 2022
Messages
15
Location
Sparks, NV
Get a piece of 3/8” fuel hose around 10” long. When installing the plugs, slip it over the ceramic until it grips, and use the hose to get the threads started. It’s a lot easier to lower the plug into the hole gently, and the hose doesn’t let you cross-thread them.
 

astjp2

TJ Expert
Supporting Member
Joined
Aug 22, 2018
Messages
5,620
Location
Utah and Alaska
I just bought a $130 set of Cornwell spark plug sockets, true plug sockets will either have a rubber liner or a magnet in them. You may think that I am crazy to spend that much but the plugs I have to install are $27 each and if I break one and the center falls into a cylinder, it’s $6-8k to repair per cylinder.
 

Jerry Bransford

TJ Guru Moderator
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Joined
Nov 9, 2015
Messages
24,779
Location
Fleming Island Florida
I gapped my girlfriends plugs in her Chevy truck out to .032 MM once. :lol:
At age 15 maybe 16 I convinced my dad to let me install new spark plugs into his Oldsmobile Starfire. I think I broke the ceramic insulator on 5 of the 8 of them. :eek: :ROFLMAO: Even more memorable was he didn't get mad.
 

pc1p

I do all my own stunts
Supporting Member
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Nov 6, 2020
Messages
1,473
Location
Hills of NEPA
At age 15 maybe 16 I convinced my dad to let me install new spark plugs into his Oldsmobile Starfire. I think I broke the ceramic insulator on 5 of the 8 of them. :eek: :ROFLMAO: Even more memorable was he didn't get mad.

Florida is making you forget stuff faster than ever before!!! :ROFLMAO:

We know.JPG