Go Back   CityProfile.com Forum - Local City and State Discussion Forums > General Discussion > Automotive
Click Here to Login

Reply
Old 10-06-2010, 03:04 PM  
Member
 
RaggedOleMan's Avatar

Seattle, Washington
Join Date: Aug 2010
Posts: 56 | Kudos: +13
Spark Plug Tech (2005 Jeep Tj/I-6)

My heep has 130k on it. The last time I changed out the spark plugs was at 50k. It was running fine, no red flags or issues, I just thought it wise to change them out before I had a problem. I?ve read many threads on various forums about which brand & model plug folks are using, but, there always seemed to be conflict. So, I just went to the Jeep dealer in town, paid their prices.

2005 Jeep Tj, 4.0/I-6, 6spd

Plugs; Mopar/NGK ZFR5N
Cost; $22.20 ($3.70 each?)
Tax; $ 2.06

The factory service manual (FSM) indicates the following;

Plug Gap; .030 to .035
Plug Torque; 22ft lbs


The coil rail torque in the FSM was unclear to me. Best I could discern was 20 ft/lbs. Also, I put a light coat of anti seize on the threads of each plug, and the 4 coil rail bolts. Hope that wasn't a screw up...anyway...

I set out to change them. I started at the rear of the engine, closest to the fire wall, and for the purposes of this write up I?ll call that one #1. Here?s what I found;



The 1st plug gap had grown to .070



The 2nd plug gap had grown to .053



The 3td plug gap had grown to .058



The 4th plug gap had grown to .067



The 5th plug gap had grown to .070



The 6th (closest to the radiator/front) gap had grown to .055

The 6th plug appears to different from the others. Any thoughts as to what the conditions on the electrode(s) suggest?

Last, my heep overheated a few months ago while up at Naches/Manastash as a result of a blown, plastic cap on the flush/fill kit adapter kit (Prestone) that I installed a few years ago. It actually overheated 3 or 4 times total that day before I got it solved. My thought is the conditions of the majority of the plugs showed some indication of the overheating/preignition episode(s). But, I just guessing. What can you guys tell by looking at these photos?
__________________

Reply With Quote
Old 10-07-2010, 08:14 AM  
Junior Member

Seattle, Washington
Join Date: Oct 2010
Posts: 7 | Kudos: +11
LOL... Only one thing I can tell you that is worth reading...

You take very nice photos, be it on the trail or of spark plugs.
__________________

Reply With Quote
Old 10-08-2010, 12:35 AM  
Junior Member

Longmont, CO
Join Date: Oct 2010
Posts: 8 | Kudos: +10
The first 5 look fine to me, albeit a little old and worn. You want the color to look like a browned marshmellow on the campfire, definitely not charred. The dark one there looks like it was running rich. The computer is pretty smart about keeping the a/f ratio correct (on average). Number 6 is odd man out, it might be running rich, it may have a funny injector...?
Reply With Quote
Old 10-20-2010, 11:13 PM  
Junior Member

Wenatchee, Washington
Join Date: Oct 2010
Posts: 4 | Kudos: +10
But yes, #6 does look different. Put some new plugs in and check again after 1000 miles or so.
Reply With Quote
Old 10-20-2010, 11:14 PM  
Junior Member

Wenatchee, Washington
Join Date: Oct 2010
Posts: 4 | Kudos: +10
Check your intake bolts to see if any are loose. My YJ had many loose intake/exhaust manifold bolts. Made it run funny - big vacuum leak.
Reply With Quote
Reply

Go Back   CityProfile.com Forum - Local City and State Discussion Forums > General Discussion > Automotive
Bookmark this Page!

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Suggested Threads

Powered by vBadvanced CMPS v3.2.3

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.