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All premium autolite spark plugs, (platinum, double platinum and iridium are made in north america).
I have installed those type of plugs in many vehicles also and they always come back to have the correct plugs installed,from Jeeps to BMW's,kinda do this crap for a living.Um, I would have to disagree with everything you are stating. Jeep KJ's use "coil on plug" ignition, not waste spark. Iridium alloy spark plugs from Autolite, Champion or NGK (whatever brand you prefer) all have much lower required firing voltage than any brand of copper core plug. They were developed for OE automakers specifically for coil on plug type ignitions. I have personally installed them in over 100 Jeeps with no issue's.
Yeah I have 4.0 I6 on the brain today,had to replace every single gasket and seal on a '01 XJ's 4.0 today but the head gasket.I HATE THAT ENGINE,it never can hold oil for very long,sad part is it only had 20k on it(yes only 20K miles as some older guy owned it and rarely drove it).I agree w/ TJ about using copper-core plugs in vehicles that came w/ them OEM. However, I disagree about the 3.7 having a waste-spark ignition system. My Intrepid 3.5, for example, does have a waste-spark system. It has one coil (w/ 2 terminals) per two cylinders. That means that when it fires on the compression stroke (near tdc, of course), it also fires during the exhaust stroke of the other cylinder, thus "wasting" that spark. The 3.7 has a coil on each cylinder, so no need to waste a spark.
For the record the later years of the 3.7,I believe it started in '08 or '09,use a waste spark setup as they only have 3 coil packs on the bank one with plug wires running to bank two.
Most likely cost issue.Interesting, I did not know that. I wonder why they made the change?
I have the parts.pdf for `08 KK, and 3.7l there has 6 sparks and 6 coilsFor the record the later years of the 3.7,I believe it started in '08 or '09,use a waste spark setup as they only have 3 coil packs on the bank one with plug wires running to bank two.
Another thing,
the Autolite Double Platinums are gapped out of the box at .044 in.:freak3:
But under my hood it says .040in. so that's what I'm going with.arty52:
I put the same ones in my '02 recently (@60K) and adjusted the gap to .040. New plugs certainly got our Liberty back to getting better mpg.