4.8 with cam/injectors idles but dies in gear

[epfatboy]

Put a 4.8 together with a cam (585/585 228/230 112) and SD80's. Has a 2bar map installed and the Turbo is plumbed but charge pipe is open so I can get it running. I'm a first time efi tuner using hp tuner. Got it to idle with bannish fuel and a VE table from a sloppy tune I downloaded. Also has a Stock maf on it.

Idles and free revs okay stumbles on recovery but keeps idling.

When I throw it is gear it will keep idling but when I tip in it surges bad and will die after it rolls a few feet. I included my scan, you can see it stall out near the end 3-4 times.

Really not sure where to start, but invested in learning, have read a few books bannish vid's etc... I used the VE from the sloppy tune because I could not get it to start with the stock VE. The sloppy VE has values 50-75% less than the stock VE values so I'm wondering if I need to re-think that move.

Just need a few suggestions so that I can get it rolling so that I can start figuring out the rest of this. Any help appreciated.

[EWY]

I would place the car in Open loop.
Set the Idle to 1000 RPM (This is temporary just to get the car running)
Increase the Base Idle Airflow (You have to log STIT to see how far off the table is) Do a quick google search and you should be able to find out how to tune the Base idle Airflow.
Then you can start to work on the VE table.

[epfatboy]

I would place the car in Open loop.
Set the Idle to 1000 RPM (This is temporary just to get the car running)
Increase the Base Idle Airflow (You have to log STIT to see how far off the table is) Do a quick google search and you should be able to find out how to tune the Base idle Airflow.
Then you can start to work on the VE table.

Should I revert to the stock VE or should I start with what I have? note: the stock VE required me to remove 30% just to get it to fire.

[mbray01]

That cam is pretty big for a 4.8, its going to require you to remove a lot of fuel in the idle areas to get it to run right, its likely going to idle around 65-70kpa, and likely 85kpa in gear when you start tuning, so i wouldnt be surprised by needing to remove 50% or so fuel from those regions to get it happy.

A simple get started trick is to look at your stock ve table, and look at the factory idle area. If your idling at say 800 rpms, take the 800 rpm ve number at factory idle kpa(likely around 35kpa) and put those numbers in your new idle region (around 70kpa) this will get your fueling in the ball park, youll still need to increase idle airflow by probably as much as 75% with this cam, then start tuning away

[epfatboy]

Learned alot yesterday, primarily how to use the scan tool!

went back to stock VE
Idle rpm to 1000
set advance to 15 degrees thru idle range
turned off STFT

I also configured the Russ K Idle Air, MAF error, and AFR error in my scanner after a few vid's and an hour or two.

Went thru a few tune cycles and got it to Idle , free rev, and move around the driveway! Super happy to see it moving, still a long way to go but I feel like I have the basic's to get the idle dialed in.

EYW, Thanks for the STIT ref, that put me on the Russ K idle air stuff which is super cool, actually got my first heat cycle into the engine since I bought it over a year ago.

MBRAY, you were close with 65kpa at idle, it's at 60. I looked back at stock VE and and your tip is where I set the VE to initially start/idle, pulled a bunch more since but that's a helpful tip!

Both AIR and VE are way off, thanks for the help.

[charcoal03silvy]

You're going to need to revisit idle airflow and timing once you get the VE and MAF all squared away. The injector data and airflow model are the backbone of the entire tune. If you change that stuff, it's probably going to throw the idle off as a result. Idle tuning should be done last, imo. As long as its running and driving without dying/unsafe to drive, don't worry about idle too much.

1. Get it running well enough to not die at every stoplight.
2. Nail down the VE.
3. Tune MAF if using it.
4. creep up on timing till you're at max safe power.

This is a pretty good method to getting up and going quickly.
https://www.performancetrucks.net/fo...tricks-373848/

[epfatboy]

I have a MAF.

I have the idle in the ballpark VE is +/- 5% in the 60kpa/800rpm column @14.3 AFR, holds pretty steady around 925RPM.

To get it running safely is it just repeated test and learn cycles in the driveway tuning just small sections of the VE table? Really runs rough so i think I have a way to go.

Also should I just keep running the orig spark table for now? I sync'ed the high/low tables with the low values for now.

Also when do you think I should hook up the charge pipe again? I kinda like the idea of learning to get it going without boost then kinda starting again with the charge pipe connected, right now it idles like crap with the charge pipe hooked up.

[epfatboy]

Just read the link,

Never mind that spark question!