Yet another noob question- plugs and such

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.

Johnny O

Just hangin' out.
Joined
Apr 29, 2021
Messages
2,358
Reaction score
3,164
Location
Bellevue NE
Thank you for all the patient answers to what are likely very basic questions! (Remember my automotive skill set is mostly on air cooled VWs…)

Anyway, Here’s another:

changed my plugs today to proper NGK ZFR6F-11Gs @.040

Glad I did, as I found a few other items that needed attention when I moved the coolant reservoir.

MIL came on. Figured was due to the months old gas that came with the car. Suspected plugs hadn’t been changed.
Code reader showed multiple misfires on #4 and #6.

Plugs that were in it were Champions and while I have seen trodes in far worse shape, these were not the worst. I highly doubt these were properly gapped, as they ranged around a third larger!

But take a look at the terminals on #4 and #6. That’s carbon from arcing correct? Both those ignition coils were bone dry of dielectric grease. I cleaned them with some ETOH and swabs and added fresh dielectric grease.

As I’m unfamiliar with this sort of set-up, is the arcing a sign of sketchy ignition coils, lack of dielectric grease, or bad plugs? Or all of the above?

Put 20 miles on the new plugs and watched the code reader In real-time. No DTCs. Engine ran noticeably smoother.
 

Attachments

  • 79040826-D92A-4686-9380-43FF75E9D378.jpeg
    79040826-D92A-4686-9380-43FF75E9D378.jpeg
    32.7 KB · Views: 38
  • 78CD4463-D897-448F-B9EA-333B4D9819A8.jpeg
    78CD4463-D897-448F-B9EA-333B4D9819A8.jpeg
    1.7 MB · Views: 38
Last edited:

LibertyTC

Well-Known Member
Staff member
Moderator
Joined
Oct 24, 2008
Messages
9,081
Reaction score
1,747
Location
B.C. Canada
The sparky's need to be changed every 35k period. Your's looks like 100k + but still had a good burn color condition.
Once the gaps get eaten away, like in your photos, arcing becomes irregular & Jeeps going to not fire properly.
The Top of plug (Terminal) in black wow !! Water or moisture got in there my guess, & was never cleaned inside of pack properly.
Inspect each of the coil packs inside for any cracks/ issues & ensure you have the pack's seals in place and dielectric grease to inside of coil pack only, not to terminal.
Many just replace the coil packs as a tune up item every75-100k miles.
See 4th photo down, shows a missing rubber seal..: https://www.jeepkj.com/threads/ignition-coil-pack-replacement.59361/
 

Johnny O

Just hangin' out.
Joined
Apr 29, 2021
Messages
2,358
Reaction score
3,164
Location
Bellevue NE
The sparky's need to be changed every 35k period. Your's looks like 100k + but still had a good burn color condition.
Once the gaps get eaten away, like in your photos, arcing becomes irregular & Jeeps going to not fire properly.
The Top of plug (Terminal) in black wow !! Water or moisture got in there my guess, & was never cleaned inside of pack properly.
Inspect each of the coil packs inside for any cracks/ issues & ensure you have the pack's seals in place and dielectric grease to inside of coil pack only, not to terminal.
Many just replace the coil packs as a tune up item every75-100k miles.
See 4th photo down, shows a missing rubber seal..: https://www.jeepkj.com/threads/ignition-coil-pack-replacement.59361/
Thanks! Is fairly different from the soup can ignition coil and distributor I’m used to.

on the other hand I don’t have to change and set points, advance, or synch carbs anymore!
 

Johnny O

Just hangin' out.
Joined
Apr 29, 2021
Messages
2,358
Reaction score
3,164
Location
Bellevue NE
Good news is other than the signs of arcing, everything else was intact and in good shape. I did have to fight the urge to ring out each coil, I admit.

The wife wants to drive it to work when it gets lousy this winter, so I’ll add new coils to the winterize list!
 

larryblevins

New Member
Joined
Mar 14, 2018
Messages
6
Reaction score
3
Location
VA
I put platumin plugs in my 2012 liberty at 100,000 miles. Tired of having to change plugs at 30k. Heard they would cause misfires but at 145,000 they are still working great.
 

Johnny O

Just hangin' out.
Joined
Apr 29, 2021
Messages
2,358
Reaction score
3,164
Location
Bellevue NE
I put platumin plugs in my 2012 liberty at 100,000 miles. Tired of having to change plugs at 30k. Heard they would cause misfires but at 145,000 they are still working great.
I had nothing but trouble with platinum and the various multi trode plugs historically.

to be honest, plugs are easier to change on the Jeep than the Bug!
 
Last edited:

LibertyTC

Well-Known Member
Staff member
Moderator
Joined
Oct 24, 2008
Messages
9,081
Reaction score
1,747
Location
B.C. Canada
We recommend the NGK ZFR6F-11G copper core as this is what the Jeep KJ engineers recommended. Gap KJ .040
They have the correct heat range & a more robust center electrode.
The ignition coils fire these plugs very hot, and in the case of platinum, you may find that there is not much left of the center electrode after 35k miles ?
Worth inspecting & checking the gaps as well.

KK requires NGK ZFR-6F-11 gap .043
 

Johnny O

Just hangin' out.
Joined
Apr 29, 2021
Messages
2,358
Reaction score
3,164
Location
Bellevue NE
So, I followed up today a bit on the #4 and #6. #4 is having no issues. #6 was still random misfires. So while at the labs I busted out our trusty hotspot FLIR and took a look. As expected #6 was Hotter than the others. I didn’t bother with resistance testing on it and picked up a replacement on the way home. Just waiting for the sun to go down a bit and the engine to cool to swap it.
 

tommudd

Moderator
Staff member
Moderator
Joined
Jul 14, 2005
Messages
22,456
Reaction score
3,642
Location
Southeastern Ohio
I put platumin plugs in my 2012 liberty at 100,000 miles. Tired of having to change plugs at 30k. Heard they would cause misfires but at 145,000 they are still working great.
Give me a Liberty with Plats and one with coppers and don't tell me which is which and I can tell a difference in the way they run
Plats simply do not work well
 

Johnny O

Just hangin' out.
Joined
Apr 29, 2021
Messages
2,358
Reaction score
3,164
Location
Bellevue NE
Give me a Liberty with Plats and one with coppers and don't tell me which is which and I can tell a difference in the way they run
Plats simply do not work well
Aye, this is true in the air cooled 4 bangers too…both porsche and VW…and come to think of it the wife’s Nissans over the years too.

Mostly, I liked the forum suggested NGKs were already gapped…I hate gapping plugs almost as much as setting points.
 

Michael Wolfe

Member
Joined
Feb 14, 2021
Messages
55
Reaction score
18
Location
Erie, PA
Thank you for all the patient answers to what are likely very basic questions! (Remember my automotive skill set is mostly on air cooled VWs…)

Anyway, Here’s another:

changed my plugs today to proper NGK ZFR6F-11Gs @.040

Glad I did, as I found a few other items that needed attention when I moved the coolant reservoir.

MIL came on. Figured was due to the months old gas that came with the car. Suspected plugs hadn’t been changed.
Code reader showed multiple misfires on #4 and #6.

Plugs that were in it were Champions and while I have seen trodes in far worse shape, these were not the worst. I highly doubt these were properly gapped, as they ranged around a third larger!

But take a look at the terminals on #4 and #6. That’s carbon from arcing correct? Both those ignition coils were bone dry of dielectric grease. I cleaned them with some ETOH and swabs and added fresh dielectric grease.

As I’m unfamiliar with this sort of set-up, is the arcing a sign of sketchy ignition coils, lack of dielectric grease, or bad plugs? Or all of the above?

Put 20 miles on the new plugs and watched the code reader In real-time. No DTCs. Engine ran noticeably smoother.
Yeah there must have been arcing between the coil packs and the plug, I would suspect they are damaged. Perhaps they had a loose connection, or wasn't engaged properly, but they are probably cooked now.
 

Johnny O

Just hangin' out.
Joined
Apr 29, 2021
Messages
2,358
Reaction score
3,164
Location
Bellevue NE
Yeah there must have been arcing between the coil packs and the plug, I would suspect they are damaged. Perhaps they had a loose connection, or wasn't engaged properly, but they are probably cooked now.
Yeah, in this case I’m fairly certain it was a result of bad shade tree maintenance. In addition to non OE type plugs and likely bad gapping, plus the plugs not changed regularly, plus dielectric grease not being used properly, #6 was toasted. But 32$ for a coil, 21$ for plugs, and 12$ for a can of dielectric grease, and I’ll get some more miles on thes 170k mile engine. Still cheaper than making payments. Since the Jeep was 500$, a grand or two of repairs is fine by me. It’s not a daily driver so I’ll run it till it ain’t worth fixing and pass it on to the next sucker. LOL
 

Latest posts

Members online

Top