ickyhonda

Finaly an inexpensive solution to resistor boxes and other injector drivers like the FJO and AEM. Sure you can use a resistor box but Low imp injectors also have the name of peak and hold injectors. The reason for that is that to open them they (should) peak/open at 4 amps then hold open the injector at 1 amp. When you use a resistor box it just sends 1a total to the injector. For smaller injectors this is not a problem but for larger injectors (880cc+) the extra internal weight makes them open slower so the 4a open really helps them open crisply so they dont drible fuel. So, yes you can just use a resistor box but since the injectors were not intended to be used this way, they naturaly dont work as well. I have made a write up on how to build your own that is really easy to build (might take an hour, tops) and uses the same injector driver that AEM, FJO, ect. use. Price to build your own is well under $100

Here is the size of it compared to a credit card.




And here is the underside of the board.


Here is the BOM needed to build the board. All of the below can be purchased at digikey.com and the actual board can be purchased at jbpref.com.


U1-U4_________4X LM1949N-ND
C1-C8_________8X 399-4329-ND
Q2-Q5_________4X TIP122FS-ND
R2-R4-R6-R8____4X LVRB-.10RCT-ND
R3-R5-R7-R9____4X 39KEBK-ND
R10-13_________4X 100KEBK-ND
D2-D5_________4X FR302DICT-ND
Q1____________1X 497-4636-5-ND
R1____________1X 270QBK-ND
D1____________1X 1N4753ADICT-ND
Optional
Mounting kit____5X 4724K-ND


The last one is not necessary but recommended because the transistors can not be grounded to the ECU case.

Hooking up the board is pretty straight forward. The injector input goes to the JP1 header #1-4, ground #5 and 5v to #6. Ground IGND1-4 and connect the injectors to INJ1,3,4 and I2 (looks like they could not have the whole abreveation inj2 fit). After it is all hooked up and you have confirmed that it works, mount it to the ECU cover. The boards can be purchased through jbperf.com for $18+ shipping.

P.S. I am not in any way affiliated with jbpref.com and am not selling anything. I'm giving you this information to advance tuning for the DIYers and give people a alternative to and expencive product.

fmfkid250

Good information! cant you just reduce the size of the resistor box to increase current? how much current will the stock ECU support?

ickyhonda

If you didn't have a resistor box most P&H injectors would flow 4-5a which burns the ecu. Hondata has a video of this on their website.

fmfkid250

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ickyhonda &raquo;</TD></TR><TR><TD CLASS="quote">If you didn't have a resistor box most P&H injectors would flow 4-5a which burns the ecu. Hondata has a video of this on their website.</TD></TR></TABLE>

I am going to have to check that out...maybe split the difference of resistance. I might play around with it

SwappedTURBOegg

this is win im going to try it. i posted on the pgmfi thread also.

VeeL_B20

Good. If they work well maybe you could sell these and make some money!!!

Legion

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fmfkid250 &raquo;</TD></TR><TR><TD CLASS="quote">
I am going to have to check that out...maybe split the difference of resistance. I might play around with it</TD></TR></TABLE>

You're missing the point. You can never drive P/H injectors properly with a resistor box.

And FYI, this concept is nothing new. Pretty much every injector driver on the market uses the 1949 chips. FJO sells their drivers for $190. So for only $100 more, you don't have to fool around with ordering parts or soldering anything, plus you get a finished product with a hermetically sealed enclosure and sealed harnesses. Furthermore, if you count the fact that the FJO is an established consumer product with a solid resale value, simple cost/benefit analysis will reveal that doing it yourself is a losing investment.

It just isn't worth it. If anyone really wants to know more, just Google LM1949 and you'll get all kinds of info on how to build your own driver from other DIY articles.

ickyhonda

Your right all injector drivers use the LM1949 really the only difference between the two is that one comes sealed and the other is not. I posted that in the first paragraph of this post. For some instances the FJO would be better, there is one on my civic because I have an AEM but if you are using a factory chipped ecu, the DIY might be a more appealing option. When the unit is able to fit inside the factory ecu having a sealed unit with connectors is not necessary. Some people are cheap asses, like people using crome free instead of upgrading to crome pro just to save $175. I put you can bulid it for under $100, which is almost half of the FJO; I built mine for $65 which is a pretty good savings. It is not that one is better than the other but one might be suited to an individuals needs better.

mmuller

great info, but page you name does not exist

fmfkid250

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Legion &raquo;</TD></TR><TR><TD CLASS="quote">

You're missing the point. You can never drive P/H injectors properly with a resistor box.

.</TD></TR></TABLE>

I guess i am somehow missing the point? useing a resistor box the injectors are lazy due to the lack of current becuase the coil is bigger to open the injectors. so by lowering the resistor box's (resistance). i will be increaseing the current makeing the injector open and close faster. my question is how much current can the stock ecu handle before it starts damage. I am sure it can handle more current then a resistor box and P/H injectors!


Modified by fmfkid250 at 10:21 PM 4/9/2008

Legion

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fmfkid250 &raquo;</TD></TR><TR><TD CLASS="quote">I guess i am somehow missing the point? ...i will be increaseing the current makeing the injector open and close faster.</TD></TR></TABLE>

The P/H injectors want a high burst of current when they open because it gives them an extra "kick" to open quickly and accurately. Then they drop down and hold at the low current to allow them to close quickly and accurately. If you lower the resistance of the box, they'll get more opening current, which will help them open faster, but they'll also have more closing current, which will make them close slower.

Unless you have a driver that actually has a peak and a hold cycle, you just can't win. It will always be a trade-off between opening speed and closing speed. Also, the injectors are not rated to run high current full-time. They are only supposed to endure the current spike for a short duration of their opening cycle, then instantly drop down to the lower current. Extra current = extra heat = shortened operating life and/or destroyed injectors. Same goes for the driver in the ECU.


Modified by Legion at 2:55 PM 4/9/2008