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Discussion Starter #1
i have had fuel mileage and power issues for a while now still figure nothing out(used to get 20+mpg and had great power). just recently i all but ran the truck out of fuel and it was missing and running rough from that...fueled it and parked it, next day started it cold and let it warm up for a little then started driving easy as it was still kind of cold, it had a real bad miss the whole 3 or 4 miles i drove, it set for about 4 hours then i went to leave to go home started it up ran with no miss.

now i always think i hear and feel a miss...mostly when lugging it, and when at high speed/high rpm there is alot of engine noise that i dont know how to explain how it sounds. never did an in depth scan with ae or anything...only used ford dealer computer to do buzz test and scan for codes...no bad codes buzz test 100%.

i have been just driving it living with power loss and bad mpg but now seems like less power and the lugging miss also less smoke, this truck used to have crazy power i could race anyone with anything and win but now i gotta really work for it, and that i cant take!

considering hybrid injectors but want to know what the problem is before i do that.

sorry this is so long, any help or suggestions are appreciated!!
 

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Paul
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160 Posts
Have you done the intank mods? If you are loosing fuel pressure you are loosing power.
A cylinder contribution test will find a miss if there is one. If you have a grey CPS, don't be alarmed by slightly off numbers on 3 and 8.

Have you checked for boost leaks?
 

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Village Idiot
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Boost leaks, tank fuel foot flew apart or blocked with crud, dirty or clogged fuel filter.
 

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Discussion Starter #4
have not done intank mods, i tested fuel pressure but not with truck running it was 50 psi, i replaced the gray cam sensor with a used black one with thoughts that it caused my problems but no such luck. i tested with ohms meter at uvch and everything tested to what i was told it should. i have checked in some places for boost leaks but boost gauge shows 30 psi and thats with basically just a tuner. fuel filter is clean and has been changed several times. i believe i found the engine noise at high rpm, 5" exhaust was rubbing tranny support.
 

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Paul
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Put a hose on that fuel pressure gauge so you can tie it to the wiper where you can see it and go for a drive. It should stay above 40 psi at WOT.
 

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Discussion Starter #6
i'll have to see what i can do...do you think fuel pressure would hurt my mpgs and stuff that bad?
 

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Discussion Starter #8
no smell of fuel or white smoke...and i dont believe it smokes at 1200. when im really cruisin in high gear at full throttle it smokes a pretty good bit (i think black).
 

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Cantankerous Old Redneck
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bye bye turbo......jerk the intake side off and check the compressor wheel for play.....
 

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Discussion Starter #10
my/my dads cousin is part owner of a ford dealership and he is in charge of service, he told me to check the compressor wheel, to make sure it still had the sharp corners on the wheel and i checked play at that time as well, everything looked and felt great, the trucks makes 30 pounds of boost everytime so im not convinced that it is an air problem.

and for what its worth i have kinda always hoped to see that turbo go so i can slap in something to really do the job lol some people would get mad at me for saying that but them 7.3s take a beatin and whatever happens im prepared to fix just would like some fuel mileage in the meantime
 

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Discussion Starter #11
i checked fuel pressure tonight with it running it was makin about 50-55psi. i shimmed the regulator a little bit and it is now at about 65psi. i didnt drive it but revved it up and idling, it held steady those readings. if i had low fuel pressure i would think i would have low boost? but i make 30 psi boost everytime.
 

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Discussion Starter #13
thats kind of what i have been thinkin but hate to replace them if theres no problem...if i do replace id like to do hybrids
 

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You'll need a built tranny if you get hybrids.


Sent from my Autoguide iPhone app
 

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biostroke1
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thats kind of what i have been thinkin but hate to replace them if theres no problem...if i do replace id like to do hybrids
A computer diagnosis at Ford should be able to reveal if an injector is dropping out, and which cylinder. I have a friend @ Ford that does mine, so I don't know how much a diagnosis cost?
 

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Discussion Starter #16
oh yea i get the backdoor discount as well family owned ford dealership...it has its perks, only ever did a buzz test need to do more and drive with it.

no need for a built tranny just a big ol clutch, i have all but 80,000 miles on factory clutch with no problems just cant really spin my 37's or it slips, other than that it doesnt slip at all and it gets abused haha
 

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Did you ever find your issue? I just purchased a 2001 Excursion 7.3 and am only seeing 13mpg cruising at 60-65mph. Motor runs great but seems to need more pedal to maintain speed.
 

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Discussion Starter #18
No i have not figured it out, with yours being an automatic it may be that the torque convertor is slipping or something....being that you said it takes more pedal. if when you take off from a stop sign and the rpms go real high to get it moving, then id say convertor hard to say.

Also do you have big tires on it or anything? Everyone says that is where my fuel mileage is going, lift and tires, but that is definatly not the problem....that may account for a few mpg on take off and things like that but i notice a definate power loss.
 
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