I am going to be running a chipped PO5 ECU in my 98 LS Turbo with High Impedance 650 cc Injectors. Do I need a resistor box?



If they offer high and low impedance injectors, why would you ever need a resistor box? Still confused after searching.....wouldn't you just buy what your ECU needs?



Thanks!

 

For Honda Engines:

High Impedence Injectors - No resistor box (to alter the amount of ohm resistance) needed

Low Impedence Injectors - Post 94 need a Resistor Box in order to effectively alter the ohms so that the computer can effectively control pulse width and duty cycle of the injector.

Most companies previously created injectors that when over 550-650cc changed the amount of ohm resistance to low impedence to keep heat down with the use of the pintle in order to have them perform well. What this meant is that for a Honda, if you wanted for example 880cc injectors, since they only came in low impedence form, you needed a resistor box in order to use them (the fitment of the top of the injector also needed to be altered to fit the Honda fuel rails, hence "Honda injectors" were made)

Now, some companies will alter the pintle and other internals in such a way as to allow a large injector like an 880cc to become a high impedence injector when it was previously a low impedence one. The advantages are obvious; no need for a resistor box to be wired in, and can still be read by a variety of engine managment. The disadvantages (which are slowly disappating from better research and manufacture) are that the internals from a smaller flow rate that are being altered to flow rate that may be 4 times what it was originally designed for were failing. An example is that a 440cc (42lbs/min) injector may be altered to flow over 80lbs/min (880cc), but that injector would fail over a short amount of time because the internals weren't changed properly. So what many do is just utilize a resistor box as a safe measure.

Your ECU Needs may change if you change management systems, or the options that the use may be looking for may not be in their size. Some like myself, don't like having the internals of some injectors altered just to fit my ohm resistance. I'd like the injectors to work as intended from their original design and not altered, so I still use resistor boxes. Others don't have that concern and like the idea of "plug n Play" without the need of a resistor box.

 

I've never seen a low impedance injector modified into a high impedance, I think you're confusing things there.

 

Sorry, I meant that some injectors that there have been situations in which a company will alter say a 440cc injector have been modified to flow at a higher rate, not an from alteration in impedence. My comment was directed as to why some people will still use a high flow rate low impedence injector even when a high impendence injector with the same flow rate (which has been altered) is available I will adjust my statement accordingly.