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Discussion Starter #1
ok guys i know this has been asked alot, but how do i make a homade boost fooler??? or does anyone have one for sale??:dunno:
 

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FYI: There is no defuel on the Super Duty trucks regardless of boost amount. There is an overboost code that reduces the cycle time of the IPR. The result is a slower gain in acceleration, not a reduction of fuel. The way to see if you are setting this would be to scan for the code. This is off the top of my head and it may be wrong, but I think it is a P0236 that is the code. You can set them on 94-97's, but it is a higher differential than the 99-03's. I run a MAP Pressure Relief Valve on my 95.

However, I've seen various configurations of MAP sensor alterations and I would warn that most are ill conceived. The majority of the pressure relief set ups I've seen blow off actual boost and do not isolate excess boost to the MAP side only, leaving the manifold pressure able to rise. The electric modifications don't allow MDFR (Mass Desired Fuel Rate) on the low end early enough since they mitigate the overall boost by a percentage.
 

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...

However, I've seen various configurations of MAP sensor alterations and I would warn that most are ill conceived. The majority of the pressure relief set ups I've seen blow off actual boost and do not isolate excess boost to the MAP side only, leaving the manifold pressure able to rise. The electric modifications don't allow MDFR (Mass Desired Fuel Rate) on the low end early enough since they mitigate the overall boost by a percentage.

Unless there is something I'm missing the 4.7V Zener Diode will not cause this problem. The voltage signal will pass unmolested until you hit the ~4.7 volt mark (which is something like 22psi). From there the max signal sent to the PCM from the MAP sensor will be 4.7 volts. This keeps you just below the threshold of throwing a CEL overboost code.

Correct me if I'm wrong so I can remove it from my truck.
 

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Discussion Starter #6
ehhh guys english. haha im 17 and learning i dont know what all this means lol. from what ive heard a boost fooler lets your truck keep fueling and thats what i need...maybe im wrong??
 

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ehhh guys english. haha im 17 and learning i dont know what all this means lol. from what ive heard a boost fooler lets your truck keep fueling and thats what i need...maybe im wrong??
Yes boost foolers are needed to keep the PCM from seeing "too much" boost and pulling things back. (it isn't a defuel as Carry Explained in his post).

the issue you will see with some of the foolers is that they screw up the fuel table.

The computer adds more fuel to the engine as the boost increases.

some of the foolers don't allow the engine to see the amount of boost being sent to the engine early enough so you suffer on the low end.

Ideally the boost fooler needs to show the ammount of boost properly all the way up to 20 PSI, at this point (I think it is actually sooner but I don't know the exact number) the PCM is already sending MAX fuel so it doesn't need to konw about any more boost.

http://www.dieselsite.com/index.asp?PageAction=VIEWPROD&ProdID=31

that one works for sure

I think the Zener Diode mod that I posted first works too (i'm running it)
 

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Discussion Starter #8 (Edited)
Yes boost foolers are needed to keep the PCM from seeing "too much" boost and pulling things back. (it isn't a defuel as Carry Explained in his post).

the issue you will see with some of the foolers is that they screw up the fuel table.

The computer adds more fuel to the engine as the boost increases.

some of the foolers don't allow the engine to see the amount of boost being sent to the engine early enough so you suffer on the low end.

Ideally the boost fooler needs to show the ammount of boost properly all the way up to 20 PSI, at this point (I think it is actually sooner but I don't know the exact number) the PCM is already sending MAX fuel so it doesn't need to konw about any more boost.

http://www.dieselsite.com/index.asp?PageAction=VIEWPROD&ProdID=31

that one works for sure

I think the Zener Diode mod that I posted first works too (i'm running it)


thanks man. thats exactly what i needed to know:thumb:
so on the pressure release valve i pull the ring to let the boost out or what?
 
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