Hi all. I bought an 2012 e350 last week with enough miles to be out of the drivetrain warranty. As I was driving it home, it started running really rough at idle and at 60mph+ it started shaking like I was doing 20mph on a washboard road. The CEL came on, so I used torque to retrieve the codes. I got P0351 - Ignition Coil "A" Primary/Secondary Circuit Malfunction

I found invoices were a previous mechanic worked on it. He said that he replaced the coil pack, which cleared the code, and then the spark plug at a later date because the code and misfire had returned. He said that the code would continue to return because the internal valve seals were leaking and saturating the spark plug.

In hopes that the oil was coming from the valve cover, I pulled the spark plug to see where the oil was coming from. The coil and boot were clean and dry. Here is a picture of the plug. It should have about 250 miles on it. It didn't seem to be covered in oil. The paper towel shows how much I cleaned off of the tip of it. I put it back in and the code cleared. My thoughts of a valve cover gasket have been shattered. However, it still ran like a turn and the CEL came back.

Today, I am going to work through the diagnostics in this post in hopes of solving it.

I was wondering if anyone had any thoughts about the "valve seal leak" and its ability to cause this issue. Thanks!

 

that's not even remotely oil fouled.

Check the wiring for that COP - the connectors like to come loose, and various animals like to eat wires, so... check it all out.

 

Pulled and tested CPS. Its resistance was at about 380, so it's good. The misfire is consistent and at both low and high temps, so I didn't need to heat and test it. There is voltage at its connector.

I switched the CEL indicated cop with one from another cylinder, no change. Inspecting and wiggling the wires revealed no clues.

I hooked my spark plug tester light up between the cop and the plug. Cranked it. It didn't light up, but it might not have been seated well on the plug. I did try a few times.



I disconnected the cps to stop fuel and then grounded a test light, placed its tip on the cop's spring, and had someone crank the engine. It didn't light nor was there a spark from the tip to spring when gaped. I tried it on another coil, and it wasn't any different, so I'm thinking that the test my is flawed.

Tomorrow, I will put the multimeter on the cop's connector and see if there is voltage.

This girl doesn't give up. Slowly but surely, I'll get it figured out. Ha!

 

The fault code is indicating that there is an electrical circuit fault for coil #1. The spark plug, the CKP sensor, etc, are not going to cause this DTC.


1. Verify that switched power is available at the violet wire when the ignition switch is in RUN or START. If not, troubleshoot the power supply circuit.

2. Ignition OFF. Verify continuity of white-violet wire from the COP connector back to PCM connector C1551E pin 17. Troubleshoot circuit if open. Check for short circuits to ground and power.

If both of those checks are confirmed to be "good", then the problem is likely a failed driver in the PCM.

Good luck!

 

It turns out that there's no voltage to the COP when the CPS is disconnected lol Disconnecting the CPS is a great way to stop the engine from starting, but not for the testing I was doing. haha

When messing around with it today, I noticed that the white wire had broken on the back of the COP connector. I guess all my plugging and unplugging had set it free. It also revealed that the purple wire was broken inside of the insulation. I stuck straight pins in the wires and tested with my multimeter. I saw some voltage changes while cracking the engine.

I picked up a new connector this evening. I will put it on tomorrow. Here's hoping that it's all it was


Thanks for the help and encouragement.

 

Ahhh yes! It was a wiring issue. Rewired a new plug to coil #1 and the code cleared. Drove it around the "neighborhood" for a half a mile or so and no codes. I will drive up to the interstate this evening, run her for a few miles, and see if she shudders. Thanks again for your help and time.

 

Ugh. The shudder is still there. It happens at 60mph. The van rides like a dump truck and I can feel every bump, but at 60mph, my organs start rattling in my torso. RPMs don't seem to make a difference.

My first thoughts are tires and drive shaft. I'll look over the forums for other thoughts.

Super happy that the P0351 hasn't returned.

 

Slowly apply the go-pedal when it's happening, does it change at all?

 

 

Misfires set a DTC only when they exceed the rate established in the calibration in use. If you happen to be running an OBD 1 calibration, they're non-MILl anyway so the CEL never comes on anyway.

Quickest way to diagnose low-grade or intermittent misfires is to look at the Mode $06 cylinder misfire counts with a scan device.

 

I finally got a chance to get on the interstate. I ran about two miles and bounced between 55 and 70mph a couple of times. Accelerating didn't seem to have an effect. Anything above 60 would shake.

I've driven about 60 miles, at below 50mph, and no CEL. It is definitely running better, but I detect a slightly rough idle. I can still see one of the mirrors vibrating a little.


I drove about 10 miles (at speeds below 50mph) with Torque (OBDII scanner) tests running. No misfires were detected. Counts were all zero on multiple tests. I will drive about 100mi tomorrow at 55-60mph. I will run it then too.


Thanks everyone. I should pull all of the plugs and check for a change in idle. This is my 1st 6.8l, and it might be in my head

I really need to try to find a new wiring harness for it, the one for the COPs and injectors. The connectors are all very brittle. I guess it's due to hot Arizona summers. Anyway, I would save myself a lot of headache if I just replaced it instead of trying to solder 19+ new connectors in as they fail.... in a van! If I cannot find one, I guess I will pull it out and rewire them all at once.

I will get an alignment in the next couple of days. It is pulling to the left a bit and maybe it will help with the shudder. I might have them balance the tires too.

BTW, does anyone know what product the use to wrap the wires? That's amazing stuff. The black wrap that is like, but so much better than, electric tape.

 

Low-grade misfires are usually most pronounced just after the transmission switches into OD, usually around 45-50 MPH. Light acceleration on an uphill grade will usually magnify the effect.

Since your shaking appears above 60 MPH, you might have a wheel out of balance or some other drive line imbalance.

 

Ditto on this, and hence why I asked what happens when you slowly roll into the go-pedal.

A bad u-joint also comes to mind. Any bang/click when you go from reverse to drive and back to reverse?