Tuning the Injectors, Help with what's next

[Coz_KB95]

So, my first go at getting fuel dialed in consisted mainly of attacking the MAF. However, the more I read the more I feel like getting the Injectors properly set up is the way to go. Logically, it makes sense that it eliminates a number of variables and provides a solid base for the tune. With that in mind I dropped back and decided to reset and start from the injector perspective. Step 1 was confirming Fuel Pressure. I run a Ford Pressure regulator on the rail ... and with my pressure gauge connected, once primed and when running at idle, it hovers between 35 -36 psi, which from what I've read is acceptable. However ... the data on the website for the FRPP 42lb/hr green-tops I am running is based on 39.15psi. So I went ahead and adjusted slopes, BKPT and Voltage Offset (from instructions Decipha had provided in a post on EECTuning. Here's where I'm at:

FRPP 42lb Injector @ 39.15 psi setting from the website:

Hi Slope: 43.009
Lo Slope: 46.066
BKPT: 0.0000212

VOLTAGE OFFSET
voltage ms
16.00 0.575
15.00 0.575
14.00 0.670
13.00 0.786
12.00 0.919
11.00 1.095
10.00 1.321
8.00 2.098
6.00 4.986
0.00 4.986
0.00 4.986
0.00 4.986

Here are the adjusted values for 35psi:

VOLTAGE OFFSET
voltage ms
Hi Slope: 41.289
Lo Slope: 44.223
BKPT: 0.00002034

15.94 0.56
15.00 0.56
14.00 0.66
13.00 0.75
12.00 0.88
11.00 1.06
10.00 1.28
8.00 2.00
6.00 4.78
0.00 4.78
0.00 4.78
0.00 4.78

So, after updating all of the SP** values (SARCHG, MAF, etc) I loaded it in and fired her up. What I can say is that the car seems/feels more "Smooth". Throttle response seems to be better, although this was just idling and free-revving to some early points in the MAF to get an idea of what was going on. What I'm stuck on is ... what to do next. Below is the histogram showing fuel corrections based on my WBo2:

Plain to see, she's a bit lean at idle and in the early points of the Maf. The Car idles mainly at 160 MAF Ad-counts. Free-revving at 175 (which the tune still considers closed throttle for some reason), 200, 225, 250 and 300 (each with >300 sample counts) is obviously increasingly rich. What I don't understand, and I think it's related to my ignorance around BKPT, is the following:

1) Is everything from 175 on up the HiSlope of the injector ... or am I still in the low?
2) Should my first step be to tweak/reduce the LoSlope and richen the bottom a touch?
3) Should I move the breakpoint and if so would I be increasing or decreasing? Is the 175 MAF point too early to be transitioning into HiSlope?
4) Should I be increasing the HiSlope to lean it out above 175?

Forgive me if these are elementary questions, I feel once I have some point of reference on what I'm looking at I will be able to tweak, test and learn. But at the moment, I have no idea where to start from.

Help ... please, and as always, thanks in advance.

[decipha]

whoa

thats literally knowing enough to be dangerous

your fuel pressure is not 35psi, gauge pressure and injection (delta) pressure are two entirely different things

read the fuel pressure write up along with the fuel write up

[Coz_KB95]

Found the Injector writeup ... and the explanation around regulators and the 'regulation' of pressure. Appreciate the direction, like you said ... enough to be dangerous.

Going back to the published FRPP 42lb settings to start with ... thank you!

Any guidance on breakpoint. I recall reading that when you start out, you like to force OL, 'kick up the breakpoint' dial in the low slope for idle and then let the KAM's do their thing. I believe you reference '2' or 0.00002 as the breakpoint value. Given that the documented BKPT for thee 42's is 0.0000212 is it safe to assume I'm already there? Or would you move it further to get low slope set?

[decipha]

No I never recommend nor do I ever force OL most importantly when dialing anything in as thats when you need them the most.

Theres no need to dial in known injectors with verified calibration data.

[Coz_KB95]

Ok, could have sworn I read it, but perhaps it was out of context. With the amount of reading I'm doing lately, its quite possible.

So quick update, I dropped back to the published settings for the Green Tops. Pulled in the published settings for the SCT BA 2400 MAF ... disabled Hego2, assigned everything to Hego1 and set about dialing her in ... now I have the Hego's plugged into both banks (in the LT header collectors) and the AEM WB in the Bank2 flow tube about 8-10 inches downstream of Hego2.

As I'm watching things I see Hego1 reading Lean and correcting with a lot of fuel ... and at the same Hego2 is pinned rich ... which the WB confirms. This discrepancy between banks is something that's been troubling me from the beginning. I understand the scavenging effect of the x-pipe but I'm don't have the experience here to say 'Yep, completely normal ... trust Bank1 ... and have at it" vs. "Something may be up indicates an underlying problem because at some point, the other Hego should start switching as well.

I decided to do try a few different things, and to rule out any issues with the harness and isolate any potential problems to the actual Bank ... I deliberately crossed over the Hego's. So ... now what the ECU things is Bank1 is actually hooked up to the Hego in the Bank2 collector. I restart my fuel dial from there ... The driver side Hego (now being read as Bank1) starts switching normally and giving me what I think are reasonable corrections ~5-10%, and the wideband is confirming everything is good ... however ... the passenger Hego (now being read as Bank2) is pinned lean. Reading pretty consistently at .150 or less. The only response I really see from it in terms of heading north of .450 is on a tip in. I'm going to attach a log in the hopes someone may be able to give it a quick glance and confirm:

1) Is this behavior completely normal, something you have observed with the scavenging effect of the x-pipe?
2) Is the passenger bank legitimately running that lean? Mechanical issue (Exhaust Leak, Clogged Injector, I already swapped out the Hego itself ... same result) I would mention vacuum leak but given I have been able to get the car to idle down quite low with the spout and IAC disconnected would indicate that I don't think the motor is drawing any unexpected air
3) Something else I may not be considering?

Don't mistake me here, not looking for easy answers and I'm more than willing to do my homework, trial and error .. but I also don't want to waste countless hours tuning around what could be an issue, only to find out on my first WOT run with the supercharger pushing air that that bank1 is in fact lean ... once when it goes BANG! :)

Here's the log, bin as well ... look forward to your input and wisdom.

[decipha]

I have no idea what your seeing but I didn't see anywhere hego 1 dumped in fuel?

Your fuel error was no more than 3% in the entire log?

I have absolutely no idea what your referring to with any of this.

[Coz_KB95]

Sorry, the post may have been confusing.

That log is with the HEGO1 signal physically connected to the O2 Sensor on Bank2. Fueling error is minimal, however the behavior of the other Hego is what is concerning. It's lingering in .100 territory.

Previously with everything connected normally HEGO1 Signal connected to O2 on Passenger side, Hego 2 turned off. I was seeing much larger Fuel corrections based on the wBo2 readings taken on Bank2 while Bank1 says its running perfect fuel.

I've attached a previous log that should outline what I was seeing ...

KB-95_Oct_02_2025.xdl

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