I have a 1998 V6 4.0L.

Rough idle main symptom, seems to have a miss.

One of the things I am testing is the ignition coil pack.

The readings I get show:

Primary 3 k ohm

Secondary 30 k ohm

Are these measurements acceptable or do they indicate a problem with the coil pack?

Thanks.

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1998 4.0L Manual 4x4 Extended Cab
w/ 2007 Ranger Wheels

This is showing the secondary check is in the lower range.
If you had access to a new coil pack you could always check it and see what you get.

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Thanks for posting that reference.

Yes, I was considering going to Lordco and testing a new one in box to see what it reads.

I don't want to replace it if it isn't the source of the problem or isn't contributing to my truck running rough.

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1998 4.0L Manual 4x4 Extended Cab
w/ 2007 Ranger Wheels

how long or has the IAC valve been replaced?

If the idle is rough, but it smoothes out a little with partial throttle, my 1st guess would be a vacuum leak.
After that I'd try new plugs and wires if they haven't been changed already.

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2003 Edge 4x4 Sonic Blue 4.0 SOHC, Auto, 4.10 LSD, 4-door Supercab

when my coil pack crapped out, i had a miss that you could really feel when the truck tried to downshift.... but it idled fine, in fact i would up driving around with it like that for over a month before it got really bad and FINALLY threw a code.... also wound up fouling out the one plug really bad.

i think i would start by pulling the plugs and looking to see if one looks like it's not fireing correctly, like it's got crap built up on it, ect.... that could help clue you in. have you done the plugs & wires recently?

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2000 XLT 4X4, 3.0, Auto, regular cab - throttle cable mod, K&N drop in filter, taylor thundervolt 8.2 plug wires, autolite sparkplugs, Accel coil pack, AVS Ventshades, Rampage LED tailgate light bar, BFGoodrich All Terrain T/A tires, Trail F/X toolbox, cruse control pod light fix, Cobra 19 ultra II CB, lil wil antenna, pioneer door speakers, expo woodgrain radio bezal, 06+ mirrors & tails, powerdome hood

2000 XLT 4X4 Offroad, 4.0 / auto, supercab - the project truck!