Champion are the suggested OE brand, correct?
As far as 3.73’s and your 33’s, do you have an auto or manual trans? Im currently on 3.73’s w an AX-15 and have no complaints. Maybe Im just accustomed to it. I just recall when I had 29” tires, my shift points were really quick. Wasn’t a fan. Im sure had I crawled back then, it would have been more enjoyable, Id guess.
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This topic has been discussed ad nauseum; I am sure I will receive numerous negative comments, but here goes.
While some members recommend the iridium, some recommend the double platinum tipped and others recommend the standard plugs.
Shortly after purchasing my '01 4.0L I replaced the OLD NGK ZFR5N factory recommended plugs with the platinum tipped plugs recommended on the forum. Within less than a week my engine was throwing codes for random misfires on all cylinders. I pulled the plugs and really didn't see a problem so I went up to a friends house who was a Jeep dealership mechanic for almost 30 years.
He connected the factory diagnostic tool to the OBD2 port, revved the engine to around 1800 rpm's for 200 seconds and registered over 200 misfires on most of the spark plugs.
I told him that I had inspected the plugs and didn't see any thing obvious, but he pulled them any way. Upon pulling the first plug... he asked who put these platinum tips in; the factory recommends the ZGK ZFR5N ?
He explained to me that around 2001 the dealers were having a lot of problems with reported misfires on new vehicles along with explaining the waste spark idea and that after extensive research the factory found the problem to be the platinum plugs. Apparently a lot of vehicles have problems, but some don't.
He pulled the platinum plugs out and installed the NGK's and 95% of the misfires went away; after performing a combustion chamber cleaning the other 5% went away and the codes were gone.
Another diagnostic test was performed for 200 seconds and in that time there was only 1-2 misfires on two cylinders; I add Seafoam cleaner to my fuel once a month and the problem has not returned.
This has worked for me...