4.0L '04 uses different spark plug than '99-'03?? - JeepForum.com
 
LinkBack Thread Tools
post #1 of 3 Old 05-28-2020, 06:07 PM Thread Starter
MN Ben
Registered User
 
MN Ben's Avatar
2004 WJ 
 
Join Date: Nov 2019
Posts: 81
4.0L '04 uses different spark plug than '99-'03??

While changing spark plugs, I looked in my Haynes to verify the plug gap and noticed the '04 calls for NGK ZFR5N with a .040 gap. The years '99 to '03 call for Champion RC12ECC with a .035.
Now some may say that either will work for my '04 4.0L WJ, but when it comes to electrical components, I like to use what was installed at the factory.
I am wondering why there is a difference in plugs when be 2004 engine came out.
Any idea? As I could not find one when doing a search.


Only one kid in history had ever attempted what Benny was about to, and he got eaten.
MN Ben is offline  
Sponsored Links
Advertisement
 
post #2 of 3 Old 05-28-2020, 06:24 PM
coldspit47
Registered User
2004 WJ 
 
Join Date: Jul 2014
Location: Durham
Posts: 524
Yes, in 04 (possibly later runs of '03), Jeep switched to NGK V-power ZF5RN. That's what I always run in mine since it was OEM, haven't had any issues. Pretty sure it retains .035 gap, however. I've read several posts/articles stating the NGK idle quieter than the Champion and had minor power improvement, but that's all subjective and seat-of-the-pants.

JEEP. making mechanics out of ordinary folks since 1940.
coldspit47 is offline  
post #3 of 3 Old 05-28-2020, 08:25 PM
Waterluvr
Registered User
 
Waterluvr's Avatar
2004 WJ 
 
Join Date: Apr 2018
Location: South Bend, IN
Posts: 540
Garage
The NGK ZFR5N is what the 2004 4.0 runs, the flash programming for the ignition drivers is optimal with a 0.036 gap.
Waterluvr is online now  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome