Power FC and Injector Settings - Need Help

[Nissansota240]

Hey guys, been researching this for about a week and my brain is about to explode with the mixture of random answers and dead ended links from searching.

So here is whats going on and what I'm trying to do.

I have a Apexi Power FC for my s13 sr20det.
I am upgrading to 04-06 Subaru STI yellowtop injectors (flow tested at 530 each)

I am having a hard time finding good info on the injector latency for both the sr and the sti injectors so that I can make the correction on the FC.

Now most of my findings for the sr have been (.7 and some .58) can anyone clarify this.

Also the sti injectors have been all over the board as well.

I'm just trying to get this thing set up with the basic tune so that it can be broken in a bit, no hitting boost though until I actually get it to the shop for a real tune though.

Cliff Notes:
-Need the injector latency for
-S13 SR20DET 370cc injectors
-04-06 Subaru STI yellowtop sidefeed injectors (530cc)

If anyone can help me out here that would be awesome, thanks.

[fliprayzin240sx]

How do I configure larger injectors?
Configuring larger injectors into the PowerFC is quiet simple and takes only a few moments. You need to know the following information before you can continue


Current injector size
Current injector latency
New injector Size
New injector Lag time

Injector Size and Latency (standard units)

Unit Size Latency
RB20 260cc/min 0.890msec
RB25 370cc/min 0.528msec
RB26 444cc/min 0.772msec
SR20 (Jap Spec Manual) 448cc/min 0.584msec
Nismo 480cc 480cc/min 1.100msec
Rx7 550cc 550cc/min 0.730msec
Nismo 550cc 550cc/min 0.710msec
Aftermarket New Units (example only) 600cc/min 0.810msec


To work out new INJECTOR correction and latency;

Old SIZE / New Size = Correction
New Latency - Old Latency = Latency Correction

John plans to install 600cc injectors into his RB26 VL Turbo. The following figure's are used;

444 / 600 = 0.74 * 100 = 74.0%
0.81 - 0.77 = +0.04 msec

So he would enter 74% for correction and 0.04 as new latency

Once you have switched to larger injectors you should still check your AFR's with a wideband to ensure they are safe and acceptable.

For a list of common OEM injectors and their settings try here;

Injector Chart - Side Feed OEM
Injector Chart - Top Feed OEM


Source: Apexi Documentation

If changing 440[cc/min] to aftermarket 600[cc/min]
440 / 600 = 0.73
Enter the value "0.73" for each cylinder.

Bolt-on turbo spec. POWER FC applications assume that the injectors have been upgraded. This is why "1.000" is not entered as the starting data for the injector values.

Injector Lag Time Setting

The POWER FC includes factory vehicle injector data. If you switch to any other type of injector, be sure to perform the calculations below and input the correct values.

Changing the factory 440[cc/min] with 0.78[msec] injector lag time to an aftermarket 600[cc/min] injector with 0.85[msec] injector lag time is:

"Injectors to be used" - "Factory Injectors" = "Correction Value After Changing"

0.85[msec] - 0.78[msec] = 0.07[msec]

Enter "0.07" into the [msec] parameter for each cylinder.

*If the aftermarket injectors have a shorter lag time, add a "-" (minus) before the value.




On this screen you need to enter your new Correction% and Latency. Be sure to double check these numbers and consult your tuner if you are unsure.
If you enter the wrong values, this could be fatal to your engine so be careful.



http://www.paulr33.com/powerfc-faq/inj_side-en.htm

[Nissansota240]

Yeah read all that, but no where does it say the latency for the 370 injectors and the latency for the sti injectors. Thanks for the response though. I'm current exhausting my Google search for these latency numbers.

Edit

Seen the bottom link

So...

370 is .64
530 is around .76

?

[Kingtal0n]

the pfc has a built in latency vs. battery voltage

what you are adjusting in the "latency" section if using a commander (assuming you do not have a data-logit? amirite?) is the ADDITIONAL latency. So when you see 370's around .58- if you WANTED .58 of latency on your 370's you would actually leave the latency set to 0.00 because .58 is the FACTORY setting VS 14Volts at the battery.

Since latency is interpolated based on battery voltage, it rises and falls as the engine runs, as voltage generally does not sit rock solid throughout the RPM range.


If I was trying to just drive that car. I would set the latency to about .12 and then adjust the Injector % per cylinder DOWN until the car drove with the air fuels I desired (roughly 14.8~ while driving around easy most of the time)

Do NOT adjust the injector % at idle. Use it to dial in the WHOLE fuel map while DRIVING the car. THEN, go back and adjust idle BY ITSELF by using the actual fuel map.

[Nissansota240]

Correct no data-logit.

So if I'm understanding correct, you ate suggesting that I make the correction for injectors size and then set latency to around .12

Then see how that runs, and then go into my injectors % and and make corrections where needed while keeping an eye on the a/f readings off my wideband

[fliprayzin240sx]

Yup, once you have the latency set on the injectors, even if you're off, you'll correct for it on the fuel map when you tune it. The kicker is, once you have your fuel fine tuned, do not mess with the latency since itll throw off your whole map.

As far as the SR20 370cc injector latency, its the same as the RB25 at .528msec.

[Nissansota240]

Thanks guys, you've been pretty helpful. This should at least get me moving around till I can get it to the tuner later this month so that it can be dialed in. (Things are pretty booked up at the shop)

[Kaifd3s]

Ok I'm bringing this back from the dead.

I'm putting s15 injectors in my SR. Now from all the reading I've done it seems that the s15 injectors are 480 or 440 or 444 with a latency of about .77. The stock 370cc injectors according to Apexi are 370cc with a latency of .52.

So I'm thinking to go with the 480cc because Ive read that running 4 bar fuel pressure makes the injectors push that 480cc out. The correction I would run would be 77%. Now the latency I would run would be +.25.

Does this sound correct fellas?