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7.3l powerstroke vs 5.9 Cummins

Discussion in 'Ford Trucks' started by DAFFMOBILEWASH, Jan 12, 2013.


    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,602

    Have a new to me 01 f350 2wd which I love but hate all at the same time. The truck empty is nice driver but the fuel milage wont crack 15mpg. The power band of this truck too sits way above my normal comfort levels too. Truck needs 2000+rpm to feel any subsancial power and seems like its working too hard to me.

    Now for what really bothers me is the pulling power of the truck. The other day with a stiff head wind pulling a 5000lb dump trailer the truck was nearly at its max. Had to almost floor the truck to get up to speed. 90km/h ... I have changed all the fluids filters and high pressure oil in the top end in efforts to wake the engine up.

    Does this sound somewhat like a typicial 7.3l?? Or is the issue that I am just so use to the power band of the 5.9l my right foot needs to learn to get more into the diesel. Perhaps there is someone else out there who has owned both...
  2. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    Sound like boost leak.

    Is intercooler pipes with boots are saturated in oily?

    15 mpg it pretty bad. My 00 F350 4wd get 18 most time.

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,602

    Is there a typicial place where they fail ?? Would you hear a hissing sound ???
  4. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

  5. WilliamOak

    WilliamOak PlowSite.com Addict
    Messages: 1,988

    I've towed with 7.3s many times and hopping in one after driving any of the big 3's newer diesel's they do feel like dogs but definitely not to the extent you seem to be experiencing.
  6. tjctransport

    tjctransport PlowSite.com Addict
    Messages: 1,390

    something is definitely wrong. my 02 7.3 will out pull all of the dodges in town except for one, and that is a built pulling truck.
  7. allagashpm

    allagashpm Senior Member
    Messages: 797

    I had a leaking down pipe as well, when I fixed that and all the seals it made a huge difference. 15 mpgs isn't terrible though, in the summer I usually get around 16 with 285s, now you have the winter fuel which kills it.

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,602

    Would an engine smoker work ?? Have a friend who is a mechanic and helped him put it on a 3.8l chevy checking for intake leaks... Such a great tool too. Sorry Mrs Smith you need a intake see this smoke billowing from here ???
  9. Antlerart06

    Antlerart06 PlowSite Veteran
    Messages: 3,437

    Gears plays a factor in the power you put on the ground
    I ran one ford had 355 gears and that pulled like a turd
    I have one has 373 and 15-16 best I can get I run a programmer bigger turbo
    I have it set most time for towing
  10. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    Best thigh is to install a boost gauge and a pyrometer.
  11. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Even I can say the performance doesn't sound correct. I occasionally drive a 98 E350 7.3 with 200k. Power really isn't an issue.

    I agree a boost gauge would be a good place to start. And the smoke machine should identify leaks pretty quickly.
  12. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    Smoke machine will not able to find leak until it capable of push 20 psi.
  13. snowish10

    snowish10 PlowSite.com Addict
    Messages: 1,095

    daff I have a 2001 f350 4.10 gear with 35'' by 12 wide tires. In the winter Im getting 13.6 in the city. Im not sure what I get in the summer since i recalibrated my speedo.

    I have a dp tuner, banks intercooler and banks turbo.

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,602

    Truck runs at 2000rpm at 60mph and is built very light. Going to do the leak down test tonight to see if there issues. Quickly looked at the boots. One has been replaced already the rest look a little slick with oil but not too bad.
  15. beanz27

    beanz27 Senior Member
    Messages: 984

    Our 7.3's get 14 mpg no matter what we do if they have 4.11's, and get 12-14 pulling and 16-20 mpg with 3.73 We have no power issues.
  16. goel

    goel PlowSite.com Addict
    Messages: 1,079

    Mine was a tired old dog last week when loaded. Just noticed thursday it was due for an oil change, which happened Friday.

    It's amazing the difference it makes, it's back to regular.

    All stock, 2k Rpms at 70 mph.

    Never paid attention to mpg. It's empty so it gets filled. It's filled, then it gets emptied.
  17. NBI Lawn

    NBI Lawn PlowSite.com Addict
    Messages: 1,797


    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,602

    Built the air intake leak down test adapter and voila.... Nothing!! Everything was tight, no air loss not even a bubble with windex on the boots. Can a good scanner read boost pressures?? How about fuel pressures ?? There has to be something wrong with it, even though it runs perfect empty.

    To be honest a 6.5l pulls better. NBI Already have a 5.9 in a Ford even though it is a Louisville, best truck ever!! There is another local l7000 identicle to mine but a longer wheel base. Needs lots of love but might be the right solution for me. Buy the truck cut the frame and put a hook on load system on the back. This way it could be a flat deck, dump truck, box truck, water truck and salt truck. Perhaps there might be a new thread starting shortly.
    Last edited: Jan 14, 2013
  19. rcn971

    rcn971 Senior Member
    Messages: 213

    I regularly tow around 10k lbs and hardly even know that the trailer is back there with my 7.3s. I have a 99' 250 and an 01' 450
  20. Holland

    Holland Senior Member
    Messages: 605

    7.3's are a great engine, ive got 3 here, one with almost 270k. Make sure your ff is good, make sure your getting plenty of fuel out of the frame mounted pump. 7.3's aren't the fastest engine, but they usually pull pretty well. A programmer will REALLY wake them up, even a small one. Found a friend of mine a used hypertech for 75 bucks and put the smallest tune in for him. Made a night and day difference and helped his mileage. Another friend has an 03 7.3 and with no programmer he could pull low 20's out of it on the highway. I installed a van turbo i had, moded his idm and he got a tuner for it awhile back, it runs out pretty good now!