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Discussion Starter · #1 ·
All of a sudden driving home last week on a rainy night, the truck had less power that normal at wot.
Its a 2008 F250 6.4, mini maxx with hd300
messing around with it the last few days. on the stock setting, it makes 40 psi at wot, no defuels, runs about normal for the stock setting

If i turn it up to tow, street, or performance, it only makes 30 psi at wot, and defuels for egts pretty quick.
Reflashed to the next tune down below the hd300, same symptoms.
no codes set ever. Pulled the map, iat, and ebp and tube and cleaned all, a little gunked up but not terrible.
Coolant levels normal, oil levels normal, can move the vgt shaft easily, and it springs back smoothly on its own. Rail pressure desired is the same as actual, always. vgt pulls down to like 8% duty cycle at wot.

I dont know what to look for next.
Any suggestions would be great!!
 

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Discussion Starter · #2 ·
also one thing to add, ebp, map, and baro are all exactly the same koeo.
ebp hits about 68-69 at wot, according to a snap on scanner, not sure if thats corrected for baro or not.
 

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Bad/dirty mass flow sensor or maybe air filter minder needs to be reset? Not sure.
 

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Discussion Starter · #6 ·
Cleaned the maf, not sure what readings to expect from it in the scan tool, filter minder has never been sucked in but I did push the reset when I had the filter off anyways... Still no change
 

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Discussion Starter · #8 ·
Desired and actual rail pressure are always the same, monitored on a snap on scan tool. I set the mini maxx to performance before unplugging it and hooking up the scanner, so it should have left the truck turned all the way up.
I had the same thought about rail pressure being low, but the data stream sure didnt support it.
 

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I'm having the same situation. Either of you guys holding 30 till 6th then getting full boost?
 
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