This is beginning to be very infuriating. Between 5500 rpm and 6500 rpm I thrown a P0300 random misfire detected code. Usually the light just flashes but if I stay in that band long enough it'll go solid. I've been going back and forth with my dyno tuner for several months and we can't figure it out. I work as. Detailer at a dealership, and the techs say its dealer defect with "the neutral ignition profile" which is just a programming issue not an actual misfire. After the tech did his thing I took it back to my tuner who downloaded the stock tune my tech put on so he could see what file was altered. After a couple weeks, and sct unlocking the tune so my tuner could mess with any file he needed, we tried again and it's still doing it. S now I'm trying to get the tech to do his thing one more time (which is proving to be harder than I thought) to see if it will do it even after the tech does his thing. I just want my car fixed to where i can tune it. My goal is to be nitrous injected by the end of the year, but I can't do that if I cant solve this. Help?

 

Having written tune files myself I can say there are so many settings in the tables that you can go blind looking at them. Without knowing what your current tuner is doing it would be difficult to determine the cause.

When I have issues like this my best bet was to carefully review the data logs so that I could see what was going on and what it was exactly that caused the MIL lamp to illuminate and throw the code you describe.

So that said I would get a hood of a reputable tuner that has a lot of experience with the 5.0 like Jon Lund, or, vmp, etc. and send them your data logs and a copy of the tune file. I'll bet they could figure it out quickly. I do not know what they would charge to diagnose this. When in doubt review the data logs. The truth is in there somewhere.

 

I talked to Shaun at aed he told me what to do to fix it, says he's seen it plenty of times haha

 

The tune might not be the problem. It could be the sensor:

https://themustangsource.com/f804/misfire-515375/

 

He is one of the best tuners going. He'll get you squared away.