High or Low Impedance?

High or Low Impedance?

  • 65# High impedance

    Votes: 2 10.0%

  • 75# Low impedance

    Votes: 18 90.0%
  • Total voters
    20
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Like the title says... which type is all around better? I'm in a tossup between 65# high impedance and 75# low impedance. My hesitation is that I don't want to mod the ECU if I can avoid it.
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: High or Low Impedance?

cloneman315 said:
the ecm mod is very simple
Click to expand...
Regardless of the simplicity of the mod (I just looked it up looks like it'd take about 20 minutes), I'm still wary of doing so. I am making every effort to retain factory revertibility in my build where I can, and I'm also not a big fan of modding computers as is, I seem to have very bad luck with it.
 
berzerker

berzerker

wookie
Re: High or Low Impedance?

i had mine done for my low imp. 55 lber's not promblem whatsoever . paid a tv-vacumn repair man to solder the new inj. drivers in for me. everything is just peachy !
 
midnightbluS10

midnightbluS10

Banned
Re: High or Low Impedance?

Check this out. It may help you decide which is right for your application.

What is the difference between low-impedance and high-impedance injectors?





The important difference between low- and high-impedance injectors is the amount of electric current they require. The high-impedance injectors used by carmakers do not use much current. In fact, even if you connect one directly to your car's battery, it will not draw much juice. This is good for the car maker because the circuit in the ECU that runs the injectors can be a simple switch made from cheap, light-duty components. A low-impedance injector needs a bunch more electric current to open, about 4 times as much as the high-impedance injector. This is so much current that the injector will burn itself out unless the juice is somehow turned down right after the injector opens. Now, instead of a simple, cheap on/off switch, the ECU must use heavy-duty components that can handle 4 times as much current. The switch must also turn down the flow of electricity after the injector opens so the injector doesn't burn up. This is a much more expensive circuit, and one that generates a bunch more heat inside the computer. Getting rid of that heat raises the computer cost even more.

This business of the ECU yanking the injector open with full current, then turning down the juice to keep it open, is why you hear low impedance injectors called "peak and hold". It takes a big current (the peak) to yank them open, but a much smaller current (the hold) to keep them open.

So why bother with low-impedance injectors if they're harder to run? Because bigger electric currents can yank harder than smaller ones. As the flow rating of an injector increases, so does the weight of whatever the injector uses to turn the fuel on and off (for example, a pintle, or a disk). This is no big deal for stock injectors in the 18 lb/hr to the 30 lb/hr range. Even though they are high-impedance, they're light enough that the small current can yank them open quickly. But big (like 42 lb/hr and up) high impedance injectors are slow to open. This makes it hard to get a good idle, and kills throttle response. What if you need an injector larger than 42 lb/hr? Simple! You buy low-impedance injectors, which are available up to 160 lb/hr. The large peak current can quickly snap these monster injectors open.

So a low-impedance 50 lb/hr injector will almost certainly be "snappier" than a high-impedance 50 lb/hr injector. When the 50 lb/hr high-impedance injectors on the Acceleronics test car were replaced with 75 lb/hr low-impedance injectors, the ECU setting that adjusts for "sluggishness" had to be set back to stock. The high-impedance 50 lb/hr injectors required much more time to open than stockers, but the low-impedance 75 lb/hr injectors are just as snappy as stockers
Click to expand...

from here
 
BULLY Syclone

BULLY Syclone

Höhe Fragen!
Re: High or Low Impedance?

Have I got a deal for you..........I have a set of 86lb low imp injectors I would sell for 200.00 they only have 700 miles on them.......I am selling them cuz they are to small for my truck...not a thing wrong with them just to small

John
 
qbnkiller

qbnkiller

Conflaguration Specialist
Re: High or Low Impedance?

...yeah...the mod for the lo-impedance injectors is something I am now doing. Not very hard to do, and I am also selling a completely modded ECM. I am finalising pricing as we speak....and that is a good deal for those 85#ers, Bully! I sell them brand new for $290 a set!

I venture to say that there are a few people running the modded ECM. It should be transparent to your injectors - regardless of whether they are stockers or 95#ers.
 
cloneman315

cloneman315

Active member
Re: High or Low Impedance?

just remember if u mod for the 75s there are some real good chip programs already out there right now
 
0260IN3

0260IN3

Engine Builder
Re: High or Low Impedance?

If you mod the ecm you can still run stock injectors.


I run 75's in my daily driver 600HP Ty and it works better that stock. Nolan's got a bunch of chips for 75's and 84's in a bunch of different trucks around here and they are WAY better than a stock setup.

Don't mess around. MOD THE ECM!!
 
VermontTy

VermontTy

Support Our Troops
Re: High or Low Impedance?

Modding the ECM is just replacing the two MOSFETs, correct? Is that all that needs to be done?
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: High or Low Impedance?

qbnkiller said:
...yeah...the mod for the lo-impedance injectors is something I am now doing. Not very hard to do, and I am also selling a completely modded ECM. I am finalising pricing as we speak....and that is a good deal for those 85#ers, Bully! I sell them brand new for $290 a set!

I venture to say that there are a few people running the modded ECM. It should be transparent to your injectors - regardless of whether they are stockers or 95#ers.
Click to expand...
When you finalize your price on the modded ECM, let me know :tup:
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: High or Low Impedance?

0260IN3 said:
If you mod the ecm you can still run stock injectors.


I run 75's in my daily driver 600HP Ty and it works better that stock. Nolan's got a bunch of chips for 75's and 84's in a bunch of different trucks around here and they are WAY better than a stock setup.

Don't mess around. MOD THE ECM!!
Click to expand...
Been talking to Nolan about this... already chips for 75#'s, but I was still squeamish about doing the ECM mod.

Also, doesn't the low impedance mod require running a larger ECM fuse?
 
0260IN3

0260IN3

Engine Builder
Re: High or Low Impedance?

jjorgensen52 said:
Been talking to Nolan about this... already chips for 75#'s, but I was still squeamish about doing the ECM mod.

Also, doesn't the low impedance mod require running a larger ECM fuse?
Click to expand...


yes you need to change the main ecm fuse to a 25.
 
10secTy

10secTy

Sy-Ty builder and Tuner
Re: High or Low Impedance?

It depends, I have been doing all the trucks with just the mosfets replaced. It works great and you can still use it this way with stock injectors.

I have also set it up where you replace the sensing resitors and rewire some jumpers for a true peak and hold set up.

I have used both and with 75's this is not required the standard set up works awesome.
With 84's they are a bit more finiky and the peak and hold set up gave me more PW at idle. If you run 84 or 96's I would maybe think about the peak and hold set up.

But I have a bunch of trucks running 84's with the standard set up that run better than stock.


I also mod ecms for $125us for standard set ups and $200 peak and hold.

Nolan

VermontTy said:
Modding the ECM is just replacing the two MOSFETs, correct? Is that all that needs to be done?
Click to expand...
 
You must log in or register to reply here.
Top