Okay, I've seen people take out their stock resistors out of their PMD's and stick in a number 9 in them. I guess trying to get that maximum power out of them. From everything I've read, the difference is very little in changing the power. Can you clear this one up for me. I just changed out my PMD, and stuck same value back in, instead of a nine. I'm not in pull-offs, just have kids in pull-ups.

The difference in fuel delivery going from a #1 to a #9 (most of these pumps are calibrated to have a 4-6) at the top end is approx 4-5ccs, which could certainly be noticeable, but the PCM has to be powered down or hooked to a Tech2 to realize the change. But don't expect to change your 6 in for a 9 and notice anything at all.

I'm not gonna change mine out. I've just seen people do this a lot, and wondered: their not really gaining much, BUT more importantly, what are the down falls in doing this, if any?


Obviously, they stuck that little stinker in their for a reason, but I was just a little unsure why?


I'd like to keep my rig close to stock, but with a few modest improvements that will help it out, without sacrificing longevity or efficiency. I've gotta keep her goin' for another 100 grand hopefully.

Without a doubt, higher resistors offer negligible gains if any, and higher resistor numbers mean longer PMD energize times and decreased longevity of the driver. Its just there for emissions to prove that fuel delivery could be very precisely calibrated.

My dad's '96 came with a #1 and doesn't seem underpowered except he's running his stock timing/adv.

A pump that has been calibrated with a #1 resistor flows the same amount of fuel as a pump that has been calibrated with a #9 resistor, thats the point of having them, so that when you calibrate them they're all theoretically equal. Changing the resistors after the pump has been calibrated will change this delivery above or below spec.

Would a pump calibrated with a #1 wear the fuel solenoid less due to lower energy pulse? and, not that i want to do it, can't a pump calibrated with a #1 increase fuel 2mm per resistor 2-9. just curious.

solenoid has to close and open every injection so theres no difference there. the 'energy pulse' is no different, 12v ON, 0v OFF. A pump calibrated to a #1 resistor swapping to a #9 will give you a max of 4-5ccs more fuel

I'm sorry, the solenoid driver(I reread the above). with a #1 resistor it energizes the driver less than with a #9.

in that case yes, your right, a pump calibrated with a #1 resistor doesnt have to keep the solenoid energized as long as one calibrated to a #9 to produce the same fuel quantity so the PMD will theoretically last longer and run cooler...note which resistor I'm running.

TDG


You keep referencing the increase in fuel to cc's.


I have read 1 number change in resistor changes fuel delivery by .3mm.


I went from a #4 to a #9 and thought I had changed it 1.5mm. Bringing my total fuel delivery(at the time) to 64.


What is the relationship of cc's to mm's?

you caught me... I dont know why but I do have a bad tendency to say cc's but its not, fuel is measured in mm³/1000strokes, so I apologize, bad habit kind of slang we use at work I guess you'd say.