possiable idle torque or timimg issue

[rlchunter1956]

"TransGo,
I finally got a chance to make a log file, look at time 16:06:02, I placed a marker just after it, well now that I know I can do a log with my laptop record speed is good now (Duh!!), well it took a while to get it to do it but when it did I noticed the timing goes to like -11 to -12 degrees, I think that is the issue possibly. It pulls the RPM down to 500, which is to low since it is commanded to 800 RPM's and if it does it enough times it will set a DTC for "cannot control idle". So if you see something please let me know, but I would like to change the timing map so the timing doesn't go that low when coming to a stop, I'll look at the parameters and see if I can find where I can change that aspect, I've changed the map for like WOT and high RPM's under power enrichment tables, but this would not fall under that. If you have an Idea, please let me know,
Thanks for your help."

I posted this (just part of the thread) to TransGo and he thought it might be Trans related, but then From TransGo:

"Ok so yea, nothing transmission related at all, so it's outside my wheelhouse. Hopefully someone else can help. One thing I noticed is the voltage drops like a rock when it acts up. Probably just because the alternator turns too slow to charge but it drops below base battery voltage in the 12.1 to 12.2 range. Probably just from low RPM but I wanted to point it out just in case somehow it had a drop of voltage that caused the computer to command tings wrong."

So it was suggested to go to Engine Tuning for help. Quick history:

" I did a DOD delete, BTR stage 2 cam, longtube headers, 3 in single out the back (w/factory cat's), some port and polish on the heads. "
Log attached. If you need more info just let me know, thanks. The original thread name is "coast down 2-1 downshift"

[96GS007]

I’m not at or even by my computer, but for others that may ask the same thing….

Are your MAP and VVE tables dialed in?

There are multiple idle related tables. Are those aligned?

[rlchunter1956]

I'm still learning all the VCM editor parameters, so I'm also still learning how to make changes. I've made some program changes to my ECM and TCM, and with all the engine mod's I've done they seem to be working good, (no CEL on mostly (except the above issue sometime causes a "can't control idle" CEL), no Knock signals for too much timing, and seems to run pretty good). So I've included my current .hpt loads. I can't yet make sense of a lot of it yet, but I'm learning, so if you can look over the file and help me with the MAP and VVE parameters. I've made changes to idle parameters, but it doesn't seem to help this particular issue. To me it seems like its a timing issue, retarding to much at that particular point in the slow down idle. Thanks for your help!

[TriPinTaZ]

Your airmass and/or VVE need correcting. If these are too far off, it won't matter what you do with the idle tables. You will be chasing your tail forever.

[rlchunter1956]

TriPinTaZ,
when I open the editor, ENGINE, Airflow Tab > either dynamic or speed density, are the only tabs that list both Map and VE tables, (I don't see any table listed as VVE). I know VE is Volumetric Efficiency, not sure what VVE is. Now that said I can't seem to understand what the tables are showing me. They make no sense to me. I don't see any correlations with Map, VE, and Eng. RPM. Even reading the description below the tables still leaves me scratching my head. I looked online for possibly help in learning so of this lingo, but I haven't found anything. So, any help you can offer me to help me understand this would be GREATLY appreciated, Thanks

[TriPinTaZ]

VVE is Virtual Volumetric Efficiency
VT is Virtual Torque

You have a lot of reading to do here

Grab a beer and your computer and plan to be reading for hours and hours. Gen V stuff is no cake walk for beginners. But once you know it, its not so bad.

[Joshinator99]

VVE is Virtual Volumetric Efficiency
VT is Virtual Torque

You have a lot of reading to do here

Grab a beer and your computer and plan to be reading for hours and hours. Gen V stuff is no cake walk for beginners. But once you know it, its not so bad.

Or better yet, hire someone like Jason to do the heavy lifting on the VVE and VT tuning and save yourself a lot of grief.