Hi all,

We just resolved a very odd problem on our 6.2 and I thought I'd share in an effort to help out anyone in the future with this issue. We were getting a code P0303, P305 and P300 when towing up a steep grade. No discernible performance issues, just a CEL, sometimes flashing. It took two dealers and a lot of mechanic work on my end.

Replaced all spark plugs
Replace spark plug wires on 3 & 5
Swapped coils around
Swapped injectors around
Cleaned Throttle Body (dealer)
Compression test (160 psi)
Wiring harness inspected (dealer)
Cleaned wiring harness contacts
ECM update (dealer)
Diagnostics - relative compression, fuel trim, etc all checked out (dealer)

After all of this, we still had the same issue. I even drove a Ford Tech around with our trailer attached to log some data. The Ford Dealer was stumped and first suggested that I needed new heads or perhaps an entire new engine. They hasn't done a real compression test at the time of this recommendation, and the relative compression was good. I asked them for a quote to do the compression test ($300) - I did it myself. 155-160 psi all around.

After I told the Dealer my compression numbers, they wanted to remove the valve covers for inspection and to check VCTs. This would be around $600.

I found a single post on the forum regarding "CKP Neutral Profile Correction" and misfires. I asked the tech if he had done that particular reset, he replied that since they hadn't touched the Crankshaft Position Sensor, it wasn't needed. I asked them to do the reset to humor me. The CKP Neutral Profile Correction fixed our issue!

 

Good that you finally got a solution.

What is involved in the reset - is it mechanical or is it a dealer software fix?

 

From what I was told, just software.

 

Just wanted to say thanks as this solved the same issue for me on a 16 f350 that I just swapped a salvage engine into due to a broken valve spring on the original engine.

 

Just wanted to chime in on this old thread, since it seems to have fixed my problem as well....

2016 F250 with the 6.2

I had a misfire that only occurred when pulling my camper and accelerating up hill. This was generally when taking an uphill on-ramp to get on the interstate and trying to get up to speed to merge into traffic. The camper weighs around 11k. Somewhere around 5k rpm in 2nd gear, probably around 45-50 mph, it would start misfiring with a flashing check engine light. I would let off, it would up-shift to 3rd gear, and the misfire would stop after 20-30 seconds. The check engine light would turn off, and there didn't appear to be any stored codes.

The first time I took it to the dealer for this issue, they said the computer didn't show any problems in the history and to bring it back within 20 drive cycles of it happening. The next time I took it in, they said it needed all new plugs, coils, and wires. The only issue with this is that those items had all been replaced within the last year, and this issue existed before and after replacing those items. I thanked them for their time and told them I would come pick up the truck.

In the mean time, I had found this thread. I downloaded Forscan, purchased a USB/OBD2 adapter, and performed the Neutral Profile Correction on my truck. Last trip out with the camper, I had at least 2 different occasions that would definitely have caused a misfire previously, but this time the truck ran great. It revved all the way to red line in 2nd gear before shifting with no misfire or any other noticeable problem.