Congrats to our New President Anguss!!
Remember to like us on Facebook!! - https://www.facebook.com/skylinesdownunder

Author Topic: RB Injector Size and Resistor Info  (Read 15698 times)

b00stinz

  • RB26DETT
  • *****
  • Posts: 5819
    • View Profile
RB Injector Size and Resistor Info
« on: August 23, 2011, 08:14:27 PM »
Can a mod please sticky this

R32ONP

  • RB26DETT
  • *****
  • Posts: 1213
    • View Profile
RB Injector Size and Resistor Info
« Reply #1 on: August 24, 2011, 07:08:59 PM »
anyone have a list of what resistance each injectors are?
Steer from the rear ..... Drop it like its hot !!!

GETLOW

  • RB26DETT
  • *****
  • Posts: 3148
    • View Profile
    • http://
RB Injector Size and Resistor Info
« Reply #2 on: August 24, 2011, 10:56:42 PM »
Most modern nissans 90+ are high impediance apart from off the top of my head. CA18DET, RB26DETT

You will find they will be between 12-14ohms

Low impediance is between what they listed in the above photo 1.8-3ohms
the last set of GTR injectors I tested were 2.1ohms

With Link G4s, the mininum resistance of an injector has to be 6ohms, any less its considered low impediance and requires a resistor pack (in the G4 manaual)
If the Injector is less then 2ohms it requires a larger reistor. I can't remember what it is, but I have a bag at work with both types in it.

The resistor needs to have a good wattage rating. so your 50cent resistors from dicksmiths won't do as they will burn out.
1JZ VVTI R33 using a custom RB25DET gearbox (almost running)

Shred Motorsport
67 Pharazyn Street
Lower Hutt, Wellington
http://www.SHREDMOTORSPORT.co.nz
(04) 569 7469

R32ONP

  • RB26DETT
  • *****
  • Posts: 1213
    • View Profile
RB Injector Size and Resistor Info
« Reply #3 on: August 25, 2011, 06:25:13 AM »
cool man great stuff..

a small question..over by the turbo on the strut tower is that a injector resistor? on a r32?
Steer from the rear ..... Drop it like its hot !!!

GETLOW

  • RB26DETT
  • *****
  • Posts: 3148
    • View Profile
    • http://
RB Injector Size and Resistor Info
« Reply #4 on: August 26, 2011, 09:36:45 PM »
nope. I havn't really got a clue what it does. I have heard its somthing to do with the fuel pump relay earth or somthing. but never investagated as to what it does or for.
1JZ VVTI R33 using a custom RB25DET gearbox (almost running)

Shred Motorsport
67 Pharazyn Street
Lower Hutt, Wellington
http://www.SHREDMOTORSPORT.co.nz
(04) 569 7469

b00stinz

  • RB26DETT
  • *****
  • Posts: 5819
    • View Profile
RB Injector Size and Resistor Info
« Reply #5 on: August 27, 2011, 09:07:15 AM »
Hey on my RB20DET its all factory and everything and I don't have that resistor on the strut tower near the power steering fluid res. My car is running 20det injectors and 20det ecu. I saw on D1lema's car that he has that resistor pack.

The reason I found that chart up there^ is because I was searching around the net to see what was going on with that resistor pack.
Can't seem to find anything about that resistor pack, everything just comes up with GTR resistor packs :(

R32ONP

  • RB26DETT
  • *****
  • Posts: 1213
    • View Profile
RB Injector Size and Resistor Info
« Reply #6 on: August 28, 2011, 12:22:16 AM »
someone should suss it out and see what its for... cos ive had a few factory GTSTs which have it and some a31s that didnt have it.. didnt even have a plug on the loom...

all wher DETs
Steer from the rear ..... Drop it like its hot !!!

Chris@STM

  • RB20DE
  • **
  • Posts: 92
    • View Profile
    • http://www.speedtechnz.com/
RB Injector Size and Resistor Info
« Reply #7 on: September 26, 2011, 10:48:20 PM »
Its a dropping resistor for the fuel pump. Varies the voltage to the pump under different conditions i.e at idle and cruise a low voltage is supplied to the pump. This should be bypassed when wiring up an aftermarket fuel pump, or even you factory pump you can bypass it.
KP Toyota Starlet **Coming Soon**
Nissan R32 GTR **Coming Soon**

[SIGPIC][/SIGPIC]
Dyno Tuning | ECU Installation | Performance Servicing | Performance Workshop | W.O.F.
_________________
Join STM on Facebook
 Read the The STM Blog

b00stinz

  • RB26DETT
  • *****
  • Posts: 5819
    • View Profile
RB Injector Size and Resistor Info
« Reply #8 on: September 26, 2011, 10:56:28 PM »
Quote from: Chris@STM;573724
Its a dropping resistor for the fuel pump. Varies the voltage to the pump under different conditions i.e at idle and cruise a low voltage is supplied to the pump. This should be bypassed when wiring up an aftermarket fuel pump, or even you factory pump you can bypass it.


You legend. That clears up the mystery of the missing resistor pack! Pretty weird how its in the engine bay rather than the boot though

r32crazy01

  • RB25DET
  • ****
  • Posts: 339
    • View Profile
RB Injector Size and Resistor Info
« Reply #9 on: September 26, 2011, 11:46:37 PM »
I heard a rumor that stock autos have the resistor for the fuel pump, where as stock manuals have the same voltage full time.

Can anyone confirm this?
Current:
90 R32 Skyline GTR
89 R32 Skyline GTS-t Sedan

Stalk3r

  • RB25DET
  • ****
  • Posts: 333
    • View Profile
    • http://
RB Injector Size and Resistor Info
« Reply #10 on: September 27, 2011, 07:57:40 AM »
whilst i think its great youre here to help people out with info chris i think its important to make sure youre very clear on what youre saying, a resistor can drop voltage, but it will not vary (implying the resistor itself is able to change voltage at will) there must be an ecu or other electronic device behind it driving this change as the resistor itself is a static resistance

however finally knowing its related to the fuel pump is good, i really couldnt be assed tracing it or puling out service manuals to answer a question from someone who wouldnt appreciate the answer

Stalk3r

  • RB25DET
  • ****
  • Posts: 333
    • View Profile
    • http://
RB Injector Size and Resistor Info
« Reply #11 on: September 27, 2011, 08:00:21 AM »
Also, thread stuck

Chris@STM

  • RB20DE
  • **
  • Posts: 92
    • View Profile
    • http://www.speedtechnz.com/
RB Injector Size and Resistor Info
« Reply #12 on: September 27, 2011, 08:07:06 AM »
Sorry ill make it abit clearer. Your right it dosn't vary voltage. What i meant is say that the fuel pump relay switchs between pins 87 and 87a. 87 is straight voltage to the pump whilst 87a is via the resistor. So at idle the ecu switchs fuel pump relay to 87a so it runs low voltage and then under power and starting it runs to pin 87 and the fuel pump gets full voltage. So it switchs voltage to the pump.  Hope that clears it up. I think it is mounted in the engine bay due to the heat that is generated by it.
KP Toyota Starlet **Coming Soon**
Nissan R32 GTR **Coming Soon**

[SIGPIC][/SIGPIC]
Dyno Tuning | ECU Installation | Performance Servicing | Performance Workshop | W.O.F.
_________________
Join STM on Facebook
 Read the The STM Blog

Stalk3r

  • RB25DET
  • ****
  • Posts: 333
    • View Profile
    • http://
RB Injector Size and Resistor Info
« Reply #13 on: September 27, 2011, 08:41:30 AM »
yes thats a considerably better explanation :P

and it will generate quite a bit of heat but its more likely that its there so its closer to the controlling loom (ecu etc) and relay, that way the resistance is more likely to be accurate rather than emphasized by the wiring running to the back of the car, a resistor is always more efficient the closer it is to the source voltage.

as an aside, and to clarify for non technical people reading. it makes extreme amounts of sense to bypass it when an aftermarket pump is installed, the reason is relatively simple, an aftermarket pump draws more current, significantly more in some cases, being the resistor is a static value and cannot change the only 2 things that can vary are the voltage out of it and the current pulled through it, as the current pulled through it increases the voltage will drop, a simple VIR calculation will show you how much, heres an example for you

lets say to keep numbers round the stock pump draws 10 amps regardless of high or low voltage (this is not 100% accurate but for the sake of explaining this example its easier to say it is), and the car and therefore pump at full voltage is 12v (its not but im using it as an example, so EAD). lets say when switched over to the low voltage side the pump is fed 9v, so the resistor in the circuit is required to drop 3volts and pass 10amps so we know the 2 values for V (Voltage) and I (Current) so Voltage divided by current (3 / 10) gives you your resistor value (0.3 Ohms in this case)

heres where it gets funky, so you have all 3 values at this stage, remember, the resistor/resistance is constant, it does not change (unless its failing lol) so the 0.3 will remain with us

lets change the current draw of the fuel pump from 10 to 20amps and do the same calculation, watch what happens to the voltage that the pump will get after the resistor

V=IxR (Ohms Law, look it up, theres a pretty triangle, save it, itll come in handy, also PIV triangle helps calculate the Wattage required, its ace)
V=20x0.3
V=6v

so following the above the target voltage to the pump has dropped to 6v (by dropping 6v) instead of the originally intended 9v and this is all due to the fact that theres a resistor in the circuit, if its not there there will be no such drop (again not strictly true, there will always be a drop as the pump itself is actually a form of resistor and then theres wiring blah blah blah, but the problem is exacerbated by the fact there's a resistor there and thats the important thing to take away from this), as you can imagine this is bad, and thats not even taking into account that pumps drawn current varies constantly due to many factors, load, temperature etc. remember all the numbers ive used above are for example only, dont use any of them in your own calculations if you feel inspired to play with them

now its like 8:30 in the morning and my brain is barely awake, so ive tried to make it make as much sense as possible, its pretty simple theory (ohms law) and if you know all of the above already, great, if you dont the above will help you with quite a bit more than just a fuel pump resistor

if you need anything clarified ask, most of the time im receptive to questions
« Last Edit: September 27, 2011, 08:55:49 AM by Stalk3r »

Pandaemonaeon

  • RB26DETT
  • *****
  • Posts: 969
    • View Profile
    • http://
RB Injector Size and Resistor Info
« Reply #14 on: September 27, 2011, 09:32:22 AM »
I'm also quite sure that the max voltage you will get to the pump with that resistor in place is 12V
pure methamphatamachine

Team Sleeper