2018 5.3L Lean on decel at low MPH coming to a stop

[Landolt]

I have had this truck for a while and did most of my tuning a few years ago, with help from others. for the most part it runs great, but sometimes if am coming to a stop the wideband goes to 1.20 lambda and engine has a stumble.
I'm not a tuner, just play around with it from time to time. today had some time to take a log and see what is going on. Attached is the tune file and a short log of the issue occurring, also a normal driving log taken a few months ago.

Any help would be appreciated

Thanks,

Mod list
1.9L Magnuson
stage 1 BTR cam
DOD delete
AEM wideband

[Landolt]

Ok so I did some work dialing in my VVE since most responses say to do that. My original tune was MAF only. The tune in this post is what I have now. Still wants to stumble for a second when transitioning from drive to idle table. Like giving just a little pedal backing into garage then back to zero pedal. The log in the post above demonstrates this.

Also, just looking at the data in the Halloween log... Why to the STFT move to cell 15 then give me a bunch of fuel? Not sure I understand why or the purpose of this.

I have been reading about this SCIAP sensor and background tables Ghuggins has posted about. My kit from Magnuson had a MAF breakout harness and a 3bar MAP i installed. Is this the same thing? My throttle control is junk after 50% as well, just opens blade to 99.6. I would be willing to make his mod to get rid of the surging.

Thanks,

[GHuggins]

The sciap can be purchased through PCMofNC. It's not what you have. I assume you have one wire going from the map to the MAF? If that's so then that's the temperature sensor input.

Write entire with this one. Just open and write entire with it. Don't try to copy anything over. Made some minor background changes for you.

[Landolt]

Yes there is one wire going from a sensor in the manifold to the MAF. After looking back at the install manual, the harness i have is to bypass MAF temp sensor and use the one they sent for the manifold.

The MAP is connected to a factory harness.

I downloaded your instructions on how to install the sciap and get with the other guy on the user defined tables. Will try to do this project over the winter.

Thanks for your help with the tune, i will get it flashed in today!!!

[GHuggins]

I should probably note that I changed a couple of other things in there for you. I'll just list what I changed.

Lowered throttle rate to help with the self opening - may wind up requiring more, in fact probably will

Upped pedal progression in the same throttle areas - will both make peppy and more controlled

Changed your traction settings - now when you press the traction control button it should be completely off

Changed 2 other torque limiters. There are 2 torque limiters based off of speed that can be in play at all times - most experience stumbling off the line for instance or just "lacking" in power even though nothing looks off. Pretty sure these cause timing to be rapidly cut to intermittent cylinders and the scanner won't pick that up. These aren't in play anymore for you. Just keep in mind they're tied to the speed limiter so no more easy cut, once you're there it's nose diving so be aware of that.

Anyway that's what I changed for you on top of some other minor tweaks off of the log.

[Landolt]

This is great!! I haven't had time to do a log yet, but I believe you are correct with bumping up the DD a bit. Throttle feels a spongy around the 50% area, but it doesn't surge either. Will be ordering some fittings and the sciap harness from PCMofNC. I am a Machinist so I will make my own custom remote MAP block and use my old stock 1 BAR sensor. Going to TEE into the port for the bypass actuator for now. hopefully if budget permits eventually go with the smooth boost setup as posted by Will_974.

I will post up a log later if you want to look it over after your changes.

GHuggins you da man!!

[Landolt]

The stumble i had originally posted about is all but gone. I attached a mixed driving log. normal driving, holding gears to fill out STFT table, WOT from cruise on highway. Doing that is the first time i am seeing some KR in lower RPM ranges with more airmass. Just so I can learn... What would be next steps in getting the tune perfect. Just want to know how you would interpret the data.

Thanks,

[GHuggins]

Finish up VE and MAF tuning especially around idle. Looks like the background throttle area adjustments "may" have taken care of the large majority if not all of the throttle opening on it's own issue. You'll still need the sciap and the DD needs some more fine tuning, but it looks a lot better. You may even find that some of those background tables need some minor tweaking to either make it more peppy or less sensitive. As stated those are some touchy tables that all adjust in unison with the torque outputs and DD settings.

[Landolt]

I did notice my MAF was off quite a bit around idle. Thats corrected now and I brought the center portion of the DD table up slightly, kind of took some of the bow out of it. Also tweaked my SOI table around 3800 to get fuel in by 180*.

Thanks again for your time and replies it's much appreciated.