This is for my brother in-law. He has a 96 F350, 4 door, 4x4, Auto, 4.10 gears and according to him it pulls like crap. He has the the 6637 mod, 3" dp, gauges and some custom chip he had built for him. Has 6 positions I think. He also just had the trans rebuilt with some performance stuff, don't know what though. All I know is it shifts freaking hard when he puts his foot in it. Anyway, the truck when it is empty runs great. Lights the tires up when he punches it, throws you back in the seat yatta yatta yatta. However according to him it struggles to pull his 6500 lb travel trailer. The egts get hot in anything but stock, and he can only muster about 20-21 lbs of boost. Its hard to read cause the boost gauge vibrates horribly. He gave me an example. He was on the highway doing 65, he punched it and it took him a full mile before he could reach 75 MPH!!!! Then if he goes over pretty much any grade, he is down in the 35-45 mph range. The truck seems to run great, sounds good, revs up smooth, has absolutely no symptoms of problems. He is pretty upset about it. Its a beautiful truck too. He sold a nice Chevy truck to get this one, and his Chevy would pull the trailer better with a 350.

So what do you guys think? I am kinda just scratching my head. I would like to help him out though.

 

haha. his chevy will be no match for this when it gets fixed.

but I couldn't give you a good answer on it.

My best guess is that his cat is plugged.

 

You didn't mention tire size but if he's runnin stock with them 4.10's 60-62 mph is gonna be his best spot for mileage and right in the middle of his torque range.... anything faster and he's just wasting fuel. Maybe the chip will help but I'd say thats probably the problem, may need to be reburnt, something is just not right......

 

Give the intake boots a look. Into the turbo from the air filter and into the intake manifolds from the turbo. Check the up pipes too.

 

He has a slightly taller tire, the same size as mine actually. I believe its a 255 85 16. Ill see if he took a look at his intake boots. I want to say he did because he just replaced the fuel pump under there. He also deleted the cat and muffler. It pulls just as bad when it was with out the chip as it does with it.

 

Give the tranny fluid a check also. He has something wrong big time.

 

The tranny was just rebuilt. Cost him around 3k I believe. It didn't pull any better before the rebuild either.

I just don't get it. I am going to see if I can take it and pull something with it in the next week or so. I feel bad for him.

 

WAG but did he go through the fuel bowl when he changed the pump. That whole deal gets really ugly inside. You open them up and wonder you the fuel could flow through all the crud.

Maybe check in the local forum for your area and see if anyone has a good scanner and run some tests.

 

Tell him to unplug the map sensor try running it and see if there is an improvement also check the hose to see if it is blocked.

 

Id check the fuel bowl fpr screen and filter and check the fuel pressure there. If its ******* under a load with no cat, then he not getting nuff fuel.
Id unplug the map sensor and try that as well.

Id test the ipr sensor too. Might not be getting enough oil pressure.

 

not to mess up his thread but i unpluged my map sensor and mine run worse is that good or bad?this is my 1st powerstroke and i have no clue on these things i've allways run 460 gas motors.
thanks john

 

John, it it runs about the same or a little worse then it's working. Unplugged the MAP the PCM makes a best guess on boost and fuel delivery. I've unplugged mine a went on short test drives just to see the performance difference in the past.

 

something is definately wrong. what kind of chip does he have? it should be a night and day difference between the chip and without it. its either a fuel problem or a chip problem. im thinking they burned the chip wrong. high egts and no extra power in anything but stock? check fuel pressure and clean the screen like others have suggested and if that doesnt help id say he has a bad chip

 

Did you mean ICP sensor?

 

generally speaking, high egt's mean its getting plenty of fuel. Does it smoke? I'm thinking like Muktown, bad chip.