Coil Pack testing

[kdjack]

I have ’97 4.6 that is missing. I’ve changed the plugs and wire, both Motorcraft. I ohm tested both Coils the primary on both is good all of the secondary’s are bad, infinite all the way across. My question is would it run at all like this or am I missing something?

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[AZTriton]

I don't think you're testing the secondary properly; how did you test? If I remember, testing the primary, put on probe on the lead, the other grounded. I'm sure others will chime in as I may be incorrect...

[jbrew]

Yea, you have to stress test unless you have primary failure of course. It's cheaper just replacing the pack, -after you've exhausted all other possibilities.

[kdjack]

For the primary I’m checking the center blade (+) against each outside blade (-) all read 0.7 ohms. For the secondary I’m checking resistance across the plug wire terminals 7&4, 8&2, 1&6 and 3&5.

[glc]

Ohm testing a coil pack only detects major problems. They have to be load tested. Are you getting a CEL? Have you scanned for codes?

[kdjack]

I'm getting misfire codes for p0307 and P0308 cylinders 7 & 8 misfire and p0171 bank 1 too lean.

[jbrew]

You have a WDS ? Y or N ? No ? / revert to post 3.

Oscilloscope /Channel 3 is for COP, not sure which channel for pack, use pack 4 gang I believe/then select "Auto" /then select "STRESS_TEST_RED". This pre-configured setting will zoom-in on the peak firing of the coil pack being tested. Fire it up.

Some misfire issues can be difficult making the oscilloscope an important part of your diagnostic toolbox.

If without, revert back to post 3 in this thread.

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Disregard 171. Complete 307,308.