Getting a P0351 (only) code and have replaced coil pack, plugs and wires. But still run rouh at idle, want to pin only wires from coil pack to other end to make sure no breakage.

https://www.yourmechanic.com/article/p0351-obd-ii-trouble-code-ignition-coil-a-primary-secondary-circuit-malfunction-by-spencer-clayton

p0351,p0352,p0353 and p0354. It won't start because you have four cylinders not firing . P0351 - Ignition Coil A Primary/Secondary Circuit Description: See the description for DTC P0350. Possible Causes: See the possible causes for DTC P0350. Diagnostic Aids: See the diagnostic aids for DTC P0350. Application Key On Engine Off Key On Engine Running Continuous Memory Coil-on-plug (COP) ignition testing - GO to Pinpoint Test JF . GO to Pinpoint Test JF . Coil pack ignition testing - GO to Pinpoint Test JE . GO to Pinpoint Test JE .
When you see these codes , it's time to worry . These ford coil on plug system's can fry the transistors that control the coil firing . New computer or reman at ford $ 800.00 buck's then it needs to be programmed (dealer) What engine ? 3.0 v-6
This happens when the spark plug's are neglected , gap get's to wide , make's coil's over heat an break down , spark goes through the primary wire to the computer . Your best bet , take it to a qualified repair shop.

P0351 OBD II Trouble Code

First of all, even though the Issue says Coil Pack, that does not necessarily mean the Coil Pack is Bad. It could be a Loose Connection, it could be a Bad Wire, it can also mean a Bad Spark Plug or fouled Injector but to answer your question...

The Coil Pack is located under the Plastic on top of your Engine and Directly connects to the Spark Plug. If I was you I would Swap the #1 and #3 Coil Packs and see if the Fault Code follows the Coil Pack. If it does then replace the Coil Pack. If it stays with the Cylinder, I would be checking the Connectors, Wires, Injector and Spark Plug.

From a reputable repair website:


P0351 - OBD-II Trouble Code

Auto Systems and Repair

Ignition Coil "A" Circuit Primary/Secondary Malfunction Our emissions expert has put together the following information about the P0351 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.
OBD II Fault Code

• OBD II P0351 Ignition Coil "A" Circuit Primary/Secondary Malfunction

What does this mean? The ignition coil or coils are responsible for igniting the air/fuel mixture inside the combustion chambers. Without reliable performance from the ignition coil(s) the vehicle will stumble and misfire.
Code P0351 indicates there's an electrical problem in either the primary ( the computer side ) or the secondary ( the spark plug side ) of the Ignition Coil "A" Circuit.
Symptoms

• Check Engine Light will illuminate
• Engine idles rough
• Engine misfires on acceleration
• In rare cases, the engine may not exhibit noticeable symptoms

Common Problems That Trigger the P0351 Code

• Defective Ignition Coil(s)
• Defective Spark Plug(s)
• Intake Manifold Vacuum leaks
• Carbon buildup in the Throttle Body air passages
• Defective Idle Air Control Valve or Electronic Body

Common Misdiagnosis

• Ignition coil(s) replaced when cause of the malfunction was a vacuum leak
• Spark Plugs replaced when cause of the malfunction was a vacuum leak

p0306 refers to cylinder 6 misfire detected===causes engine mechanical fault--wiring---ignition/fuel system--injector ---ECT/MAF sensor---ECM
IF there was a mechanical fault (hydraulic follower ) or valve it would be there most of the time and not just on start up. Possible injector fault but I would be inclined to check out the MAF sensor codes p0351 &2 refer to ignition coil A and ignition coil B primary /secondary--circuit malfunction === causes --wiring--ignition coil--ECM ( all causes for the both)
going on this check out the coils and check that the wiring and connections are clean and tight. basically I would be inclined to change out the coils and check /replace the MAF sensor.
change the engine --sounds like advice to get some extra money out of you.

i think this has a coil pack, if so it is a common failure it will give a random misfire code most cases. and also the crank sensors are known to fail .. jay

These codes are for a malfunctioning ignition coil/s.
P0351= ignition coil A primary/secondary circuit malfunction.
P0354= ignition coil D primary/secondary circuit malfunction.
visually check the coil packs for burn marks, damage, loose wire connectors, and the wire harness to each of the coils for damage. How long has this been happening? Has any work been done recently? Did the engine compartment recently get wet?

Has anyone found the problem? My 2003 has #3 cyclinder misfire and I have replaced the plugs and wires. It runs rough at idle but smooths out at highway speed. Anyone have any knowledge on this? This sounds like a common problem.

The code reads: ignition coil #1 primary circuit. If the coil pack has been replaced, then it is likely the PCM (computer package) is defective and needs to be replaced. That circuit is driven directly by the PCM. This information was taken from a '96 Dodge Caravan service manual (3.3 V6 engine with coil pack ignition system), and should be similar. If your engine uses a distributor instead of a coil pack, then the above code doesn't apply. Even if it does apply, the code implies a 'miss' situation, not complete engine stoppage unless the computer operates the 'automatic shut down relay'??