Cylinder 4 misfire/no spark
This is about my wife's 2008 2L City Jetta SOHC.
So I had a multi-cylinder misfire error code (and barely ran - very rough) - I replaced a couple spark plugs and ended up replacing the ingnition coil pack. Ran great for a while - no codes.
Now misfire has come up again (P0304) for cylinder 4.
I've replaced that spark plug, and all the spark plug wires, keep in mind the ignition coil pack is basically new.
I've swapped the cyl 4 fuel injector with another - no change.
I've checked for spark and didn't see any. I checked by pulling the plug, connected the plug wire to it, and held it against the engine while running - let me know if this is not a valid way to check for spark.
So I'm about at my wits end - any suggestions for troubleshooting?
I think I have to start checking the wiring back to the ECU.
If anyone has any wiring diagrams, ECU connector specs, etc... available it would be greatly appreciated!