EdHag

I have a 2010 F-150 with the 5.4L v-8. Today for the second time while towing my 4500 lb camper in more than an hour of rain, the truck is misfiring and threw a running lean code. It happens as the truck down shifts to 5th or 4th gear pulling uphill. I have pulled the camper thousands of miles and it has only happened after driving in steady rain for more than an hour. Any ideas on what's happening? I wonder if something is missing on the truck that keeps the moisture out of the intake or some underbody truck part that physically blocks rain from getting up in the electrics. Thanks for any help. My local dealer was perplexed.

KingDeleted

I cant believe the 2101 f150 is still burning fossil fuels! Ok enough. When your going uphill under lots of load you get a misfire? I would say its fuel related and change the fuel filter first. Are you saying that under the same circumstances in dry wrather there is no hesitation or misfire?

EdHag

Correct. Never happened in the dry, only in rain, and only after been in it a while.

acdii

You have a bad COP. Reason you only see it happen when towing is due to the extreme load the engine is under going uphill with a load. Under the same weather conditions unloaded, the spark is more than likely hot enough to not cause a misfire. With enough moisture, it can cause a leak to ground and sap enough energy that the plug gets loaded from not a hot enough spark.

G-Force

I was going to say close to the same thing. It could be insulation worn off around a COP or its wiring, causing it to short out to the engine block in high moisture air and either weaken the spark, or no spark at all.

EdHag

Thanks for that!
How does one determine which COP is bad? I have not gotten a code for misfiring, just the one code for a month ago last time it happened in the rain. The code was a PO150, system too lean bank 1.

I did get a tuneup with new plugs a few months ago at 100,000 miles. Plugs were replaced but I don't know if that typically includes the COP's. Wondering what to expect from the dealer who is working on the truck. I've changed out a lot of plugs and made living as a junior mechanic/assistant 20+ years ago but I heard that these 5.4V8 plugs are tricky to change and can be broken easily, hence taking the truck to a dealer. And I am a "senior citizen" now so it's not so easy to get upon in there...

G-Force

Did you have two different codes?

P0150 is O2 sensor circuit malfunction, bank 2 sensor 1.

P0171 is system too lean, bank 1.

Bank 1 is the passenger side of the engine and bank 2 is the driver side of the engine.

Here is some info on the codes to help you:

P0150

P0171