superstealthcc

Hello! Need a bit of help here. Noob HPT tuner here by the way. Setup is as follows- 98 LS1/PCM, twin turbochargers, 2 Bar SD with Siemens Deka 80# Injectors.

I borrowed the injector data from the sticky on the 80LB injectors and borrowed spark and VE tables from Denmah. I know the tune still needs work but I cant get it to idle above 11.3 AFR. As you will see in the tune (file attached), I started cutting a lot of fuel from the VE table (around idle) and got the AFR to go from about 10 to 11.3. I kept cutting fuel from VE and was not able to raise AFR anymore.

Thanks in advance!

Charlie

gametech

iTrader: (1)

I get an error when trying to view your tune, but I'm guessing a minimum injector pulse table has been overlooked somewhere.

MontecarloDrag

iTrader: (3)

Use a shorter name and upload again, can't download the tune

T/A KID

iTrader: (12)

Simple fix... Need to adjust the minimum fuel... This will make the IPW low enough to get a clean idle

jimmyblue

iTrader: (11)

With such humongo injectors, do you have a manifold
referenced fuel pressure regulator? The reason for the
short pulse limit is that injector actuation time is both
finite and variable; telling it to go less than it actually
takes may make operation unreliable (how well and how
consistently does a half-opened injector shoot?).

But a manifold referenced FPR lowers the fuel pressure
at light loads and for the same minimum pulse width
you get less fuel. That might let you keep a sane idle
pulse width. Plus it fights the fuel fade that's always
there with the in-the-tank regulator, which doesn't
know from nuthin' but head pressure.

NicD

iTrader: (7)

SD 80# injectors are relatively dirty at low pulsewidths, by far my least favorite larger sized injector. Either way it looks like the offset data is on the high side compared to what I've calculated for those injectors which is going to skew it rich, and I would drop your Min Fuel Milligrams down to .010 to make sure it doesn't affect the pulsewidth down low. Actually your injector flow rate looks way low unless you are running lower fuel pressure with an aftermarket regulator, etc which is going to make it rich as well.

jmac636

iTrader: (8)

I can get the sd 80lbs to idle as lean as I want them to without any issues. Just set your Min fuel milligrams to 0.020 and you'll be fine. You may have something else going on. Well, I just looked at your tune and looks like you have the maf still enabled bud. When tuning the VE table you have to disable the Maf. Maf frequency fail needs to be set to 0 and go ahead zero out the maf table. Also from the looks of your VE table your not adjusting the right area of the table. Usually you need to adjust cells between 55kpa and 45kpa under 1200rpms.

Johnny_B

I'm having the same issue as the OP. similar set up, turbo 4.8 (gen 4) with 80lb semiens dekas, 450 walbro pump. ill attach my tune file and log, if your interested. my data is very similar to the OP's. Also I'm not sure what table you guys are referring too when you said 'min fuel mgs'. I'm new to tuning, Ive got an at home course, but it doesn't help with this rich idle issue.

Please help guys, any ideas would be appreciated! thanks so much.

MontecarloDrag

iTrader: (3)

Go to the FUEL tab, then go to TRANSIENT tab. There is a parameter (not a table) called Min Fuel milligrams. It is usually .024, lower it to .014, or maybe a little lower.
Be aware that those injectors are big for a 4.8, I have them in a 5.3 and they struggle to idle at 800 rpm and 14 AFR. when I try to lean it they start to behave erratically and cause misfires. 1% adjustment makes the AFR go from 14 to 17 and a rough idle

Johnny_B

as I feared, my version 3.0 of HPT doesn't have the value in the same spot, or likely; its labeled something else. heres a screen shot of what I see under transient. anyone know how version 3.0 shows the min fuel mgs???

Jacktuner

siemens injectors always seem to be causeing trouble with someone, i had s set of 80's and they were junk, i bought s set of ID injectors and they are much better to tune, chalk and cheese difference

Johnny_B

I regret buying them... But I didn't know. So many guys run them, you just assume they aren't bad