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OverFuelingForYourPlesure
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Discussion Starter #1
I have been working on a local kids 99 f350 and am pretty much stumped.
it is a 4x4 extended cab 6speed truck with factory sized tires and 3.73 gears and he is only getting about 13mpg.

here is where It gets a little complicated he bought the truck with a salvage title and it has a newer engine and computer (I found that out when his early 99 TS chip he bought for it wouldn't work right when I installed it for him)
but any way here is what I have checked

fuel pressure never drops under 60psi
new air filter
no exhaust leaks
good icp (it will set the low icp code in fuel 7 setting but I'd expect that)
starts good
passes cylinder contribution tests an every other test I can run.
ebpv is open and I unhooked it.
makes 15psi of boost and about 20psi ebp in stock setting .

I did think it was odd in fuel7 setting the ecm only read to 15psi of boost but climbed to about 30psi ebp with no over boost code and no boost fooler is that normal on ts tunes?
it dosent have a boost gauge so I dont know if that is all it is making or not.

is there any thing else I need to be checking:confused:

Thanks
 

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is the odo correct? How about his right foot? How's his driving habits? I have found that if I gas on it a lot the milage goes to crap. That's terrible milage. My dually in my dp 40T with 12K+ toyhauler gets 11.5 on a 150 mile trip with lots of pulls, 3 of which are from 5-9 miles of 6%. 16-18 around town on the fwy if I don't gas on it. Haven't checked it since the Adrenaline was installed. That was with a tired 15* hpop.
 

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OverFuelingForYourPlesure
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1,609 Posts
Discussion Starter #3
he says he has been driveing it for milage and i have no reason to believe otherwise. I hooked my computer to it today for the first time in about 2 months and it didn't have any over boost or low icp codes in it.

I know the family pretty good and do most of the work on their trucks. they take good care of their stuff
 

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OverFuelingForYourPlesure
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1,609 Posts
Discussion Starter #4
also forgot to mention that the EOT and IAT sensors seem to be reading properly.
and the truck will put out a decent puff of smoke in the high setting but not a huge about or anything. no noticeable smoke in the stock setting.
 

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have you tried it with the chip unplugged? Is the pcm compatable?
 

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OverFuelingForYourPlesure
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Discussion Starter #6
it had poor milage before he got the chip, and I reburned it with the proper tunes for his computer.

he said the chip helped his milage slightly but not very much
 

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Sounds like you need a pro instead of me. I'm out of ideas. Good luck.
 

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OverFuelingForYourPlesure
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Discussion Starter #8
thats where I amLOL
 

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what cps does he have? i switch my grey one to a black(napa) one and my mileage went from 15-17 to around 13. I went through one tank so far that got 13 and went half way through another and have got 170 miles out of it, gonna ride this tank out and if its still low ill switch back to the old one.

Not really technical, but for 20-30 bucks you might want to try another CPS. I believe most people have really good luck out of the IH cps, sorry but i dont have a part number for you. Ill watch this thread to see what happens.
 

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riverjet
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459 Posts
I switched from the FORD black cps to the new dark grey/purple and did not like. I think it pulled timing and lost slight power. Did run quieter. Sorry not trying to derail.
 

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OverFuelingForYourPlesure
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1,609 Posts
Discussion Starter #11
Talked to ts today about the how much boost the computer was reading and they didn't think something was right there. I am going to swap out the MAP sensor and see if anything changes.

if that dosnet do it I'll try a cps
 

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OverFuelingForYourPlesure
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Discussion Starter #13
he is running highway
 

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DON
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Dark Blue CPS P/N: F4TZ-12K073-C
Black CPS P/N: F7TZ-12K073-A
dont no about a drak grey or the grey one got mine at parts guy ed
 

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check the brake calipers and make sure there is no drag on any of the 4 wheels. Check the tire pressure and maybe make a post in the MPG forum here. Dave might have some advice
 

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what about drivetrain?

wheel bearings? brakes dragging? pinion bearing/axel bearings

probably something wrong there given it has a salvage title maybe it was in a wreck?
 
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