I am having 2 issues that I can not seem to find a fix for. After a lot of searching I have found several other people with the same issue but no solution. I have a 99 5.3 silverado with a 216/220 .600/.600 112 lsa, mildly ported 862 heads (208cc intake, 79cc exhaust, stock chamber), long tube headers, y pipe, no cats. 4l80e swap, 50# delphi injectors and e fans. Problem #1- after driving and everything is warm it will sometimes go lean and stall out when stopped but in gear. It does not happen every time. I have done the sloppy mechanics iac relearn with no success. Problem #2 - while driving, when I let off the accelerator the engine stays idling around 12-1300 rpm and does not go back to regular idle until i come to a stop. I will post the tune and a data log, if anyone as had this issue and found a fix I would really appreciate some input its diving me nuts. Thanks in advance.

 

# 1 sometimes the throttle closes to fast causing stalling. You can slow the throttle blade by RAISING the tables in the Idle > Throttle Follower > Decay (Gear). If you go to high it will be slow coming down so you'll need to back up to the sweet spot. I'd start by raising the tables 20% .

Do the cracker (#2) first so these tables won't be conflicting one another. Do #2 test drive then # 1

# 2 disable the throttle cracker should let the idle drop when coming to a stop. To disable enter a speed idle never sees like "enable 100mph" and "disable 98mph".

 

These are among the most common issues following a cam swap - and there is indeed a solution. I will say, before you try to tackle those problems, there are some other fundamental things to fix. One being the injector data - you need to enter the rest. There is more to it than flow rate. Idle spark needs to be increased - underspeed/overspeed needs to be reduced. To start, add 4 degrees to idle spark and cut the over/under tables in half. Right now, it has plenty of air but no spark authority to make torque, so that's part of why its stalling on you. I'd wager the randomness of it is due to your e-fans and not having any airflow added to the fan airflow scalars. You've added a bunch to base running airflow, but that's not where it all needs to be - and too much in base will cause the idle to hang. Need to add some airflow to throttle follower and potentially throttle cracker. You also need to clear out the long term fuel trims. There is a 15% addition, opposing your negative fuel trims.

I admit that was very disorganized rambling. Start with those things, get more data and post up again.

 

Thank you guys for the input. Ill work on those things and see what I can come up with.

 

I dont know if I got it all covered but I swapped over some more fueling data from a tune I got for the injectors Im running and added to the idle spark. I just took a little drive down the road and it actually felt a little better down low and the few stops I made it didnt stall out and die. It usually takes it several seconds after I stop and so far it looks good. I tried to message you but I couldnt attach the files.

 

Looks better. Now time to fix that fueling. I personally wouldn't disable throttle cracker - it is a good tool to manage engine braking. It has a few other uses as well.

 

My afr is reading 10-11 until my coolant gets to about 180* is that normal?

 

That's too much. You shouldn't need anything richer than 14 beyond around 140f ECT. Varies by setup...but yours isn't too extreme.

 

Found a post by RussK over at HP Tuners forum saying the stock 2004 5.3 "Open Loop EQ Ratio" tables are the best he's found. RussK set the standard for LS idle tuning so it's probably good info.

This is the file he uploaded to HP Tuners.
I run these Open Loop EQ tables and they work well for me.

EDIT: after comparing the two files the RussK tables will run richer in OL so I wouldn't change.

 

Open loop EQ will depend on the engine combo. Bigger camshafts are not a fan of the sharp decrease in OL EQ at lower manifold pressure, which is common for stock settings. That area happens to be the cold start engine temperature that the EPA75 emissions test begins at, so you can guess the reason for those settings.. I give some more sciencey detail in this post/thread:

https://www.performancetrucks.net/fo...ueling-557214/