Recently I purchased a 2006 E250 with a 5.4L engine and about 153k miles. I’m aware I probably overpaid, but I didn’t mind since these vans have a reputation for being solid and long-lasting. There was no check engine light at the time, so I thought I got a good deal.

Unfortunately, about halfway home, the check engine light came on 🤣. I was pretty shocked—I guess I got played by the seller. Surprising, right?

The codes I’m dealing with are P0351 and P0356 (cylinders 1 and 6). So far, I’ve replaced the ECM, coils, and spark plugs, but the issue is still there. One thing I’ve noticed is that when I clear the codes, the van runs perfectly for about 3 minutes. After that, the codes return and it starts misfiring again. If I clear them, it runs fine briefly, then the cycle repeats.

Does anyone have any idea what might be causing this? I’ve seen suggestions like a bad alternator, faulty connectors, or a grounding issue. Any help would be greatly appreciated—thanks in advance.

 

I doubt if it's a grounding issue... both the COPs and injectors get continuous power and the PCM switches the ground side of the circuits.

One thing that is probably not related: I noticed that 1 & 6 are every fourth cylinder in the firing order meaning the crankshaft is in the same position on both misfires.

 

Do you think this is the problem then?

 

That's an oddly specific match to your issue. I'd definitely check into that.

If I'm reading it correctly they're saying it's a problem in the connector, not the sensor itself. Do you read it that way as well?

 

yes the connector but I guess I’ll check the sensor too

 

To eliminate the alternator, I was about to suggest unplugging the plug and see if the problem returns after clearing the codes, but it was already suggested.

Take a good look inside the rubber boot that goes over the spark plugs for those cyls for carbon tracking. If you see it ,replace the boots.

Is there any way you can get some idea of fuel trim? That could help give us some idea of whether it might be fuel involved and not necessarily entire electrical.

 

I will see if the scanners I have show any fuel information. Thanks for your help in advance

 

I have a 2006 E150 since new. Several years ago, i had the same persistent issue. Finally threw up my hands and went to dealer. They found broken wire in the harness. $800 repair but no issues since. Don't start firing the parts cannon without an accurate diagnosis!

 

When we get a repair for a specific problem, we always look for why we did not find that. That broken wire for $800, can't quite determine which wire that could have been.
Did you ever decide to look for where the repair was made ?

 

thank you for your response