Idle VE table areas

[JHForman]

Ok quick issue, I have been slowly working on my tune and I am happy with my progress. My issue comes from idle, my AFR will never stay or really change all that much. I idle in the 800RPM 30 and 40 KPA cells. The scanner is constantly telling me that I need to add 9-10% to the 40KPA cell and the -6-9% to the 30KPA cell. I have adjusted and changed these 2 cells over and over and I'm not seeing much of a change, if any at all really. I have 44 in the 30KPA cell and I'm up to 75 in the 40KPA cell. The 44 is believable for idle but not the 75. I will attach the tune so someone can offer me some insight hopefully I feel like I'm missing something obvious. I have the ECT/IAT bias turned off due to my sensor location.

[Higgs Boson]

what are your mods, do you have headers, cam, etc? put it in open loop and use a wideband, trims are unreliable, especially at idle with a cam.

[JHForman]

5.3l, s475, walbro 450, Bosch 105 injectors, Holley hi ram, custom, headers.

[JHForman]

Already in open loop LTFT and STFT disabled

[dually681]

check for vacuum leaks. header leaks.

[JHForman]

check for vacuum leaks. header leaks.

Checked all that already, once the truck is hot no matter what I change it idles at 12:1

[JHForman]

heres a log of my idle with truck hot(I drove home from work)

[dually681]

fuel pressure?

[JHForman]

55 base psi I'm thinking about lowering it tonight before work just to see what happens

[JHForman]

No change lowering base pressure

[dermotw]

You have bigger injectors I think(?). Are u sure that they can go so low? Log the injector duty, see what it says... possibly they just won't go any lower? Downside of big injectors - you can't control the low flow end so well.. (imho, and I'm not any expert...)

[JHForman]

Definitely bigger

[dermotw]

Sorry should have mentioned, you can log the pulsewidth as well, it'd be more important at idle, where it's near the minimum possible (probably)...

[JHForman]

Lowest I can get the pulse width down to is 1.9, the truck idles fine and drives fine just crazy rich at idle and nothing changes it

[JHForman]

I should also mention if I command closed loop it will go to the correct afr

[dermotw]

Ahh well it's not that then if its ok in CL!
Seems like you are probably in PE mode all the time(?). See the PE EQ ratio (gas) table, it's set so if you are in PE, it'll be around 12.7:1 even at idle. Tweak the low end values e.g. up to 1200rpm to 1 and see what happens...

[JHForman]

Tried that no change

[SSUte01]

Lower the Transient Min Fuel Mass (like half or less than you currently have) - Those are some big arse injectors and without seeing your airflow modelling, if you have lowered this without change to pulsewidth, then this is a possible cause.

[dermotw]

Hmmm.. and yr lowest PW is 1.9mS... I was running that on MINE at idle, which is NA and with 36lb inj... don't think you can go low enough! It will idle at 12:1, just waste some fuel & keep yr engine a bit cooler, lol.

I'm hoping someone who knows will chime in, because I don't know about Turbo's, don't know how big yr injectors need to be.. do u know what duty cycle/PW they reach at WOT and heavy load/peak rpm?? 80-90%?? If they are properly sized, it'd be around that.

EDIT: SSUte01: looks like he's done that... but perhaps not enough??

EDIT: I just looked, he's at 0.018, hell that seems low to me anyway, I'm at .028, and it's easily enough for my quite different setup..

[JHForman]

Well anyone who knows is going to say go but injectors you can get the correct data from(ID 1000), i unfortunately do not have 1000$ laying around to buy another set of injectors on top of the 500$ I have already spent on these