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Mazda Millenia This sedan, the flagship luxury sedan, offers both a naturally aspirated and supercharged model, so you can have your luxury, and, if you have a need for speed, big horsepower.

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Old 02-06-2007, 06:30 PM
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Default Plug gap

Why does my owners' manual state sparkplug gap @ .031,and other sources tell me .044?
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Old 02-07-2007, 09:17 PM
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Join Date: Jul 2005
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Default RE: Plug gap

Don't know. Maybe you have the wrong owners manual
Spark plug gap for the 2.3L millercycle KJ engine is .028"-.031"
Spark plug gap for the 2.5L KL engine is .039"-.042"
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Old 02-07-2007, 10:25 PM
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Join Date: Dec 2006
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Default RE: Plug gap

I have a 1995 Mazda Millenia owners' manual.Has specs. for both the 2.3 and the 2.5.I have a 2.5.On page 9-3,this is howspecs. read:
2.5 liter V6 DOHC Miller Cycle Engine V6 DOHC
number ZFR6F-11 PZFR5F


Spark-plug gap 0.031 +0.000 in. (0.8 +0.0 mm)
-0.004 -0.1

I just got a set from NAPA, they gave me NGK (G-power)ZFR5FGP.I'm thinking these are platinum(?) plugs.They have a very small tip.Is this why I'm hearing a gap of .044 (?),because the "updated" plug allows more gap to be used?
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Old 02-08-2007, 11:38 PM
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Join Date: Sep 2005
Posts: 983
Default RE: Plug gap

look at the plugs under the 2.5. zfr5f-11. the -11 means that these plugs are pre gapped at 1.1mm(.044). NONE of the plugs under the mc column have a -11, plus, there is another brandof spark plugs. then, at the bottom, it gives the gap for these TWO different brands of plugs. so, what it is saying, is for the 2.5, the ONLY plug recommended is the ngk zfr5f-11. for the 2.3, either ngk or denso is recommended, and the gap is .8mm. i think the napa plugs are gold palladium, an alternative precious metals tip. most modern day cars use the 1.1(.044) gap, IF they are normal aspirated. a FORCED INDUCTION motor will always have a smaller gap, because it takes much more voltage to produce a spark when the pressure is higher, which it is in a fi motor. to produce a good spark, it has to either have much higher voltages, or a smaller gap, or both. the cop system on the mc motor gives more positive voltages, and a smaller gap on the plugs insures good combustion. i am continually amazed at people who believe partspersons at napa, pep boys, autozone, yada, yada over what mazda tells you, or what a mazda tech tells you. mazda is concerned that the correct parts are used, so you can keep the car for a long time, and be happy. napa dont give a squat if you can even drive, they just want to sell you parts.
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