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Discussion Starter #1
howdy all :)

just joined a few minutes ago...recently picked up a 99 f-250. i'm working through some bugs here and there. mostly small things....i hope.

here's my question. now and again when i'm cruising at a steady speed/rpm the motor backs off/hesitates/loses power and i hear and feel a constant "whoomp whoomp whoomp" sound/surge coming from under the hood. if i let off the throttle it goes away and if i get on the throttle i get full power back.

what could this be? i've replaced all the hoses and checked everything around the turbo/intake etc...replaced the fuel filter also. truck also had a programmer in it...i've removed the program and set it to stock.

i'm not sure what else to say here....looking for help!!

thx in advance!
:)
 

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turbo compressor wheel. you will find quite a few here have switched to a wicked wheel to eliminate this problem. I haven't experienced it myself but I've see a fair amount of posts about it on here. Hope this helps and I'm sure someone a little more experienced with this will post up later.
 

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Oh yeah, Welcome to the org. Lots of nice people and tons of info and help here.
 

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Discussion Starter #4
sweet thx for the info....i'll check into this.

and thx for the welcome!
 

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Just remember internet diagnoses is difficult at times and to be patient as discription of problems are not as clear and multiple issues may exsist.

Not saying yours isn't but it is possible you might have other issues.I do agree with the surge problem as an issue.

Does it do it in stock form?Is the truck stock other than the programmer?Are you pulling a load or a grade?
 

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Discussion Starter #7
thx...just read through the thread. it sounds like these guys are having issues during acceleration and pulling a grade. i only hear it when i'm rolling at a constant speed...whether i'm in first, third, second...gear. but, other than that every symptom jives....
 

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Discussion Starter #8
programmer has been removed. previous owner straight piped the the truck...still has 3" out of the motor though. it's lifted....believe 6" lift. and running on 35's. other than that it's stock to my knowledge.
 

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Discussion Starter #9
Are you pulling a load or a grade?
to clarify...i only hear/feel this surge when at a constant speed. when i get on it...surge goes away and i have 'full' power/acceleration. when i get out of it....surge goes away.

definitely agree that internet diagnosis is difficult. just lookin for as many opinions and points of views i can get!
:)
 

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Discussion Starter #11
a little bit....but i've always understood that a miss in a diesel is quite noticeable...no?
 

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Discussion Starter #12
and it doesn't really "shake"....when i hear the surge under the hood, i also feel it. kind of rocks me a forward and backward a little....know what i mean?
 

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Discussion Starter #14
does this truck have a back pressure valve for the exhaust? if so....could that not be functioning properly? just thinking....
 

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Discussion Starter #15
it will shake if it misses and depends a slight miss you will not notice as much.

Idle and all is fine just constant cruise speed?Is the cruise control engaged Or light throttle psi from your foot?

yes...idles fine...cruise control doesn't work. just with light constant throttle with my foot...
 

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Discussion Starter #18
yeh man....that's what i'm wondering about....if that valve isn't working right, i.e. sticking closed or closing and opening when it feels like it....could that be my problem? even at normal operating temps?
 

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You will hear it in the exhaust it has a noticable hissing sound and is plausable.Time to get dirty if that i what it could be.You can wire it open.You can also unplug it.The plug is on the pedastal up front.You have to pull the Y out to get to it.

like I said earlier internet diagnoses is hard especially when you try and base findings off sounds that are heard.I am trying here and hopefully someone else could give a few more pointers.

I don't know what else you could try.My truck hates slight constant pedal psi and I know it is related to my inj's haveing issues.It bucks and snorts heavy.
 
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