I would compare one of those plugs to the old ones. make sure they are exactly the same. Washers and everything.

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

Firing order and wires are all correct. Regapped it and it starts and runs fine on high idle as it warms up it gets worse. Idle is sitting around 800rpms and still has a miss to it.

Do you have the original MC plugs. Put 3 of then back in the passenger side.

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

You've got serious detonation going on in two cylinders judging by the discoloration and coating that was burned off. do what modelageek said ,Seafoam the intake , fuel system, and get some maf cleaner and clean the mass air flow sensor.

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2014 F150 xl 3.7 6 speed auto.

Just for the hell of it I pulled the rear two plugs on the passenger side. Middle gap was down to .50. The rear is down to .45. I'm throwing two of the five original plugs that I can find back in just to see. All the gaps on these 5 are at .60. Not touching the gap.

Compare the old and new for size, etc

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

Why would detonation pop up all of a sudden?

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The plugs are identical in shape and size. No washers, just shoulders on the plug body. Rear two are in. Going to fire it again and see what happens.

Is it under warranty?

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

If they gave you hotter running plugs that can cause detonation.

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2014 F150 xl 3.7 6 speed auto.

What is the part # of the old plugs?

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

This

It should still have most of its warranty left. The NGK's could have been hotter. These Motorcrafts are direct replacements. It ran like crap with those two old plugs. Should I try gapping to .60 on all cylinders would the original plugs have burned equally away by .06 thou each in 86,000 km's? Whats that 53,000 miles?

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Agsf 24n

Well. That failed miserably too. It sounded pretty good and was holding idle a little over a grand but as it warmed the rpm's dropped and it threw a light on. Think I may be off work on a sick day to get this thing sorted out.

So if the NGK's were hottier or offered less resistance would that have screwed up the coil?

Need to find out what code it threw.

Sent from my SCH-I545 using Tapatalk 2

Anyone ever heard of this or experienced it?

Water intrusion into a connector (X309) located under the cab, beneath the driver's seat, can cause a rough idle, erratic speedometer operation, ABS Light and Check Engine Light illumination, and automatic transmission shifting problems. If needed, connector repair parts are available from Mazda dealers, and possibly some Ford dealers.

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2002 Mazda B4000 4.0 4x4 auto trans,L/S 4.10s 2750 lbs capacity. ext cab. P245/75R16. Has off road package, towing package, cruise, tilt, auto dim rear view mirror, am fm cd, power locks and windows, and a leer camper shell.