What spark plugs to use with 784 injectors?
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Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Member
Joined: Apr 2013
Posts: 126
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From: Sonoma County Ca
Year: 2000
Model: Cherokee
Engine: 4.0L inline six
That if you dont have the proper gap it can affect performance. Did you not catch that from my last three posts, yeah the last part is not entirely clear as im talking about two different things in one post oh dear may get to confusing... to all others if you use platinum plugs do not gap.. do not clean... and do not remove unless your changing them.. thats all
Last edited by JeepsMyName; Jun 23, 2013 at 11:28 PM.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Every 30K miles, replace your plugs, wires, cap and rotor. Do not waste your time and money on platinum plugs in a 4.0 because there is no performance gain and probably a performance loss.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
That's a given. How do you know the platimums are gapped for optimum performance since you don't check them, gap them or remove them?
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
How about being a Service Manager and Shop Foreman at a Jeep dealer from 1980 through 1992? Think I may have learned a bit during that time and since then? I grew up with these Jeeps. Way before and after all these miracle plugs and crap. Probably before you were born according to the attitude I see.
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Joined: Apr 2013
Posts: 126
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From: Sonoma County Ca
Year: 2000
Model: Cherokee
Engine: 4.0L inline six
Thats awsome much respect to you. But when you bla bla bla to valuable information I would say the same to you. You get what you give. Im never the guy who is unnecessarily rude so let me give you some info on platinum plugs... Not gapping plugs is hard to get used to, but you should not gap Iridium and Platinum tipped spark plugs.* The Iridium or Platinum is only a coating, and is easily damaged.Do not gap Do not clean Do not remove The only “maintenance” is replacement. One time installation, one time removal.
Last edited by JeepsMyName; Jun 23, 2013 at 11:45 PM.
Seasoned Member
Joined: May 2013
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From: Sucka Free East Bay Cali
Year: 2000
Model: Cherokee
Engine: 4.0
). BTW the the old Asian gentlman who helped me at O'reilly has been working there forever(since it was a Grand Auto). He may even be Japanese. Well just before he rang me up he looked at me with a stone face dead in the eyes and asked,"what motor you put these plugs in?" When I replied Jeep straight six he smiled and said "Ahh yes, Champion very good." No B.S.
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Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
No they are made in the usa $2 a piece. How do I know this? Well I thought i'd install the ngk's because the recommendations on this forum seemed more performance and longevity oriented than those on other forums that seemed more politically motivated(ngks are for ricers etc.). I called 5 different supply houses in my area and none carried the ngk coppers(2 said they could special order them). I didn't feel like waiting so I purchased a set of the applicable Champion coppers (chumpion, champon etc). Now that they are installed I plan on pulling them after the thirty(If they last that long
). BTW the the old Asian gentlman who helped me at O'reilly has been working there forever(since it was a Grand Auto). He may even be Japanese. Well just before he rang me up he looked at me with a stone face dead in the eyes and asked,"what motor you put these plugs in?" When I replied Jeep straight six he smiled and said "Ahh yes, Champion very good." No B.S.
). BTW the the old Asian gentlman who helped me at O'reilly has been working there forever(since it was a Grand Auto). He may even be Japanese. Well just before he rang me up he looked at me with a stone face dead in the eyes and asked,"what motor you put these plugs in?" When I replied Jeep straight six he smiled and said "Ahh yes, Champion very good." No B.S.::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Thats awsome much respect to you. But when you bla bla bla to valuable information I would say the same to you. You get what you give. Im never the guy who is unnecessarily rude so let me give you some info on platinum plugs... Not gapping plugs is hard to get used to, but you should not gap Iridium and Platinum tipped spark plugs.* The Iridium or Platinum is only a coating, and is easily damaged.Do not gap Do not clean Do not remove The only “maintenance” is replacement. One time installation, one time removal.
Besides, platinum plugs are a waste in our old Jeeps. They were designed for very extended plug change intervals in cars with higher output ignition systems than our Jeeps. They actually require more voltage to fire than a simple copper plug.
I personally have had issues with Bosch single platinum, Bosch Plus 4s, AC standard, AC platinums, Splitfires, and standard champions.
I have NEVER had an NGK failure in 45 years of working with engines.
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Joined: Apr 2009
Posts: 18,786
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From: CT.
Year: 88
Model: Comanche (MJ)
Engine: 4.0 HO
I agree with the Bosch plats.. In all my years in the shop I started using those at one time and stopped after a few comebacks with random misfiring.
Worst plug ever even in newer cars.
Worst plug ever even in newer cars.


