I have two pdm's.one has a #9 resistor and the other a #5.What do the resistors do?Any advantage using one or the other?

I believe the #9 is supposed to increase performance by adjusting the PMD. I think the #5 is stock. I ran the #9 but hard to tell any change.

Thanks for the reply! has Anybody else changed the resistors and noticed any difference in power or mileage?

You are only talking about less than 1% gain with resistor change......it's not enough to blow off your BVD's.

You are only talking about less than 1% gain with resistor change...it's not enough to blow off your BVD's.
Actually...each individual resistor is about 3/4 of a mm / 1000 strokes.
So the difference in a 5 to a 9 is about 3mm. Still not a vast increase, 4-5%, but arguable noticeable.

Keep in mind, its not like you can just change the resistor, fire up the truck and it will be different. The resistor itself changes nothing, they could have put the resistor in the fuse panel. The PCM has to read the value of the resistor and then apply the change to the fuel rate.

Marginal increase, main noticeable difference is on WOT stab off idle.

So a #9 will give more fuel than a #5 resistor?What is the lowest numbered resistor I can use and do you think it will increase fuel mileage?What does WOT&BVD stand for?

wot- wide open throttle

Your right foot will dictate fuel milage, not the resistor. The resistor is more or less a way of calibrating the pump I believe.
BVD's=underwear

thats sucks they delted my defention of BVD

Yeap It crossed that line you ain't suppose to cross here.

i understand what you mean it didnt seem to bad just something i rembered from school there only body parts but your doing your job good job you caught that quick

No Problem and thanks for understanding

Thanks for all the replies but still don't have a clear idea of what the resistor does.thefermanator says it calibrates the pump.Someone else says it effects fuel delivery.So my question now is:when would you use different valued resistors and why?

So a #9 will give more fuel than a #5 resistor?What is the lowest numbered resistor I can use and do you think it will increase fuel mileage?
Calibration resistors come from #1 to #9. #5 is the most common, and it does no change to the fuel delivery quantities the pump is putting out.
#1 is the highest trim, about the same 4-5% less than what a #5 would give you, I doubt that swapping in a #1 would change your mileage at all. Going to a #9 won't cost you all that much in fuel either.

Just think of that calibration resistor as a "spacer" under your go pedal. Limiting the travel of how far it will go, and limiting the fuel that the injection pump will supply to the engine. Make sense?

Resistor is found inside the connection of the PMD. Look inside and you will see a little piece of silicon with a number on it.

So a #9 will give more fuel than a #5 resistor?
What is the lowest numbered resistor I can use and do you think it will increase fuel mileage?
Calibration resistors come from #1 to #9. #5 is the most common, and it does no change to the fuel delivery quantities the pump is putting out.

#1 is the highest trim, about the same 4-5% less than what a #5 would give you, I doubt that swapping in a #1 would change your mileage at all. Going to a #9 won't cost you all that much in fuel either.

Thanks for the info.Makes sence to me now.