P0350 '03 Kia Sedona

Been checking out your videos, didn't know you had an active forum!

Kia sedona 2003 3.5 wastespark
Vehicle would start but idle terrible and limp.

I only have the Torque app and elm dongle which only pulled P0350.

Found one coil visually arching,
then found another coil arching.
Found ignition harness extension not fully seated/ not plugged into coil of cylinder #2 bc of a bent pin on old coil.
Replaced all coils with oem/Denso.

Ignition wiring harness extension was falling apart every time I touched it, terminals were not secure in connectors. Was told it was just replaced. Guessing old Harness was falling apart too, and they replaced with another heatsoaked aged brittle plastic Harness that was also falling apart.. Ordered installed NEW ignition extension harness.

After installing all new coils and harness found cylinder #2 coil still wasn't firing. (and associated cylinder #1 bc wastespark)

Tested ecu driver for that coil (green wire, terminal #12 on ecu) and found shorted/grounded internal ecu. Short/ground is only present in wiring when plugged into ecu, so assumed rest of wiring was fine.

Purchased used ecu on ebay. It does not have a short/ground on terminal #12 green wire when plugged in to ebay ecu, but that coils green signal wire still doesn't pulse the test light, the 2 other signal wires to the coils pulse the test light as I would assume the 3rd green control wire should too.

I don't know if I got a bad ecu or something else is going on.

Other things on mind are the ignition failure module, cam sensor, crank sensor, but I assume each of those would trigger their own specific codes and most of the videos I watch about the other sensors/modules would have other codes or a complete no start situation.

I haven't pulled the timing cover yet to inspect cam sensor and I haven't done a compression test.

I checked the fuel injector on cylinder #2 / coil that isnt firing, the injector on that cylinder #2 is still firing.

I have a new spark plug wire set that feeds to the back head and new spark plugs but I haven't removed manifold yet to change rear plugs/wires. Should I do this first and then see whats happening? I have no idea the condition of the rear plugs under the manifold.

How can I verify the ecu I received is good or bad that could be causing my problem now. And/or what could be causing the other cylinders to fire, but will not allow this one control wire to cylinder #2 to fire?

I'm trying to help out a friend here and dont want to buy any unnecessary parts for this pos so I'm kinda stuck atm, what am I missing?

Hope that all made sense

Disclosure- self taught and still learning these testing procedures.

Thanks for the informative videos! Appreciate any help!

I know it's just an old Kia, but would like to figure this out if possible

Is the P0350 present with both the new, and old, ECU?

After installing all new coils and harness found cylinder #2 coil still wasn't firing. (and associated cylinder #1 bc wastespark)

Cylinders #1 and #2 are NOT companion cylinders. Companion cylinders are (1 and 4), (2 and 5), (3 and 6).

Purchased used ecu on ebay. It does not have a short/ground on terminal #12 green wire when plugged in to ebay ecu, but that coils green signal wire still doesn't pulse the test light, the 2 other signal wires to the coils pulse the test light as I would assume the 3rd green control wire should too.

Can you describe your testing. Are you back-probing at the ECU? Or, at the coil? With the connector connected? Or, disconnected. Is the test-light connected to battery POSITIVE? Or, NEGATIVE?