Steve Bryant

iTrader: (1)

Did anybody ever figure out what triggers the PCM on the trucks to switch to the LTFT Cell 22? I have a 2000 Yukon XL with the LQ4 6.0L and I only go to Cell 15 at WOT? I can't figure this out. I have a factory maintenance manual, but they don't address the prerequisites for Cell 22 operation. The thread on this issue ended abruptly in January. Any light shed on this issue would be appreciated.

Thanks,

Steve

samz28

there's a thread on hear or hptuners.com which shows the cells, and how you can modify them to be more ls6'like

I might try altering the ltrims to be more accurate in the range that i drive around in.

efilive 6.x can actually show these VE cells in a grid for ltrims but you need edit type software to hack the cells around

Steve Bryant

iTrader: (1)

I appreciate your input. But Cell 22 is missing from the table you are showing. Also, the original question and mine have to do with what triggers the transition to and from Cell 22. I have EFILive and I can monitor and log what is happening or has happened. However, I don't know why I'm not ever going to Cell 22 even when throttle position = 100% and I am above 90 kPa MAP and I am at a higher RPM (all the way through 6,000). Evidently others who have participated on this thread have had the same situation.

samz28

post your configs in edit/tuners

are your ltft boundaries,map to enable, hysterisis,delay, min rpm all the same as the rest of us? perhaps one of your triggers is different than the 2000 ls1. You compare your bin to a 2000 stock z28?

I'm wondering the same question myself, but more specifically where is 16-21 lol. Why would someone go to 15 then 22, but skip 16-21?

sorry for butting in i'm trying to learn this shiz too. I've got edit and tuners so i can read in any of the tunes on ls1edit/hptuners if you need to look at them.

I've also (painfully) exported EVERY SINGLE parameter from my stock tune versus the modded tune in ls1edit export to text file. IMO the best way to learn is to listen and talk some . TAke no offense. I'm trying to understand the FTC as well. But i'm more interested in how one can optimize the FTC's for how i drive so don't mind me, just trying to share and learn mate.

Bink

This thread may help you guys some: http://www.efilive.com/forum/viewtopic.php?t=474

samz28

thanks just what i was lookin for.

Steve Bryant

iTrader: (1)

Joel,

Thanks. I have now re-read this thread on the EFILive.com site enough times (maybe 7, maybe 9 but who's counting) that I'm beginning to understand its relationship to my question better and better. Note: I've been following this thread since March 31; but I have this understanding impairment sometimes.

It seems that there is still some misunderstanding about the nature of Cell 22 among a lot of people and maybe Cell 23 is totally unknown or perhaps not used at all (reserved for future use). It also seems that the association of the term WOT with Cell 22 may be inappropriate.

How can I tell if I am in PE mode or not? It appears that: If EQ = 1.0, then the PCM is in Closed Loop and will command an AFR of Stoichiometric (14.7:1) However, If EQ does not equal 1.0, then how can I know if the PCM is in PE mode?

Bink

Steve - Everytime I reread that thread I chuckle to myself - I had NO Idea it was all based on a canister puking (purge)!!Too funny - that thread sure explains a lot of observations by many.

Anyway, Log these three pids ( from the thread) - I hope you have EFILive V6....
Monitor Pid - GM.EVAPDC
Monitor Pid - GM.EQIVRATIO
Monitor Pid - SAE.FUELSYS

GM.EVAPDC - will tell you if cell 22 is accessible - i.e. if purge is Off .
GM.EQIVRATIO - tells us if EQ =1.00. If 1.00 then Closed Loop. Any value other than 1.00 is Open Loop and cell 22 is possible.
SAE.FUELSYS - this will confirm Open or Closed Loop function.

So if Purge is Off/Inactive and EQ does NOT equal 1.00 then you must be in either Cell 20, 21 or 22.
IF TPS% is equal to, or greater than, the the TPS% in yourWOT/Cold table
AND your MAP (kPa) is equal to, or greater than, the PE "MAP to Enable" AND your Purge is OFF -> then you are in PE cell 22. All three conditions MUST be met: 1.Purge Canister Inactive/Off
2.TPS% - WOT / Cold
3. MAP to Enable

Note that WOT does not neccessarily mean PE/Cell 22. You must satisfy ALL 3 of the above. Purge Canister ON keeps us out of Cell 22 (and 20,21).
Does this help some ??

joel

Steve Bryant

iTrader: (1)

Joel,

Yes, I have EFILive 6.4.1 and I'll log the data that you suggest. I've also printed your response so I can re-read it a half dozen times or so because of my afore-mentioned impairment and the recurring cerebral purge cycling. If only I'd had a lobotomy, I could blame it on some external influence.

In all seriousness, I appreciate your help. This stuff is difficult to understand particularly since we are collectively trying to ferret-out PCM theory of operation information by conjecture, reverse engineering, brainstorming, etc. I guess that is part of the fun and challenge! Certainly GM/Delco/Delphi hasn't been very forthcoming with information, which I can understand. One reason the PCM's are so complex is so they can very tightly controll emissions for a number of years with very little maintenance using relatively inexpensive sensors.

Thanks again!

Steve

Bink

Steve,
You're welcome. One thing for is for sure. The info provided by GMPX on EFILive.com is factual. GMPX did the PCM work for EFILive 6 - he's dissembled the various PCM calibrations and is therefore able to see their exact functioning via the code. GMPX, Blacky, Zorab and Delphi really know their stuff!

Steve Bryant

iTrader: (1)

Thanks,

I'm working the question with the folks in the EFILive forum concurrently. GMPX steered me to page 3 of the same thread that you pointed out to me yesterday (which of course was today in New Zealand ;-). Anyway, I have printed and am re-reading and studying the entire thread (not just page 3).

I'll just continue this quest over on EFILive so as to not "double-dip" in both forums.

Thanks to you and GMPX, I'm well on my way.

Steve

Super Sport X2

Hi Guys,

Cells 20,21,22 are used when the Evap system is not running.
Otherwise cells 0-15 are used for off idle and WOT


Which one you get depends on TPS qual , MPH qual and the lower Map LTFT boundry.
With those quals you should see 22 at WOT and 21 during DFCO


Cells 16,17,18,19 are used during idle, PN, and A/C at any coolant temp.

Ken

Bink

Kennnnnnnnnnnnn................................... .....................................Kelly????

Super Sport X2

No, I'm not Ken K.

Ken C.