Intermittent P0356 code

[8306gt]

As the title says I have been getting an intermittent P0356 code along with the obvious miss which goes along with it. I have swapped coil pack location which results in the same code, as well as checking ohms on the coil both indicating a good coil. I have checked battery voltage with koeo and have 17.25 volts (KB BAS) at the plug for # 6 or F coil. I realize at this point all that is left is the ground wire from the coil to the ECU or the ECU itself. So how do I test for this with it being intermittent? I know I can ohom the wire while doing the wiggle test and if I don't find the wire to be bad, how do I test the ECU since it works correctly 95 percent of the time. Or is there something else I am totally missing that could cause this code and engine miss fire.

 

[michael.konor]

First, did you pull the sparkplug? If so, did you move it to another cylinder and see if the fault moved?

If that didn't fix it... Electrically, you can have the 17.25VDC at the plug, but still not have the correct amount of current necessary to carry the load. This commonly happens when one or more strands of the wire are broken. Same thing occurs when someone does an Ohms test, get's <6ohms of reading, and calls it good.

The lightbulb test would be my recomendation. If you hook up a 12VDC bulb and it glows dimly, check the wiring. Don't forget to wiggle the harness and see if it dims and gets brigher.

You could also do with with the ground line that goes to the ECU with the addition of a few more wires. Basically have the bulb take the place of the COP in the circuit, and ground the pin going to the ECU into vehicle ground.

 

[8306gt]

First, did you pull the sparkplug? If so, did you move it to another cylinder and see if the fault moved?

If that didn't fix it... Electrically, you can have the 17.25VDC at the plug, but still not have the correct amount of current necessary to carry the load. This commonly happens when one or more strands of the wire are broken. Same thing occurs when someone does an Ohms test, get's <6ohms of reading, and calls it good.

The lightbulb test would be my recomendation. If you hook up a 12VDC bulb and it glows dimly, check the wiring. Don't forget to wiggle the harness and see if it dims and gets brigher.

You could also do with with the ground line that goes to the ECU with the addition of a few more wires. Basically have the bulb take the place of the COP in the circuit, and ground the pin going to the ECU into vehicle ground.

All new HTO plugs, the light bulb test will show it working unless it happens to act up while I'm looking at it. It only sets the code while driving, hasn't happened yet while idling. I have done the wiggle and not found anything yet, but I admit I don't which plug at the ECU has the coil ground wires so I just moved all of them. I admit electrical issue are not my favorite thing to trouble shoot so keep the ideas coming.