What controls EST_XMSN_DMA (Trans Torque Reduction Spark Retard)?

[Mr. P.]

Hello Everyone, been a while I know - this last month I dusted-off EFILive and got back into tuning my truck, and am tackling spark timing issues/questions.... I am trying to dial-in my spark advance table, and eliminate part-throttle KR. I think I am seeing two KR issues, one is light KR under part-throttle driving (1-3 degrees), and the second is major KR (5+ degrees) under sudden load/demand or kickdown. The KR I am seeing is 'spikey' not 'sawtoothed' so I am guessing that this is more burst knock retard (?) rather than detonation, but I am not sure. To get a better idea of my issue, I logged the following PIDS:

GM.KR - zero, except for a single instance of 7-degrees under 1/2-throttle
GM.EST_BTM_DMA - zero the entire log
GM.EST_KRB_DMA - a dozen 'random' spikes of -1 to -3 degrees sprinkled about the whole log
GM.EST_XMSN_DMA - major activity, literally half of the driving was with 18+ degrees of retard

Questions:

What controls EST_XMSN_DMA (Trans Torque Reduction Spark Retard)? The torque management tables in my tune are all zero'd out, where is this activity coming from? I can see GM.SPARK PID affected by EST_XMSN_DMA, but this EST_XMSN_DMA retard is not included in GM.KR PID (I thought it would be?)

(log attached)Attachment 14324

Vehicle info - 2003 Silverado SS AWD, LQ9 stock with Paxton Novi-1500 @ 10-psi; EFILive COS3.

- Steve.

[joecar]

EST_XMSN_DMA is derived from the Shift Torque Reduction tables (i.e. torque reduction via spark timing during each shift).

As far as I can tell/see, KR includes only retard due to filtered knock event detection.

EST_KRB_DMA is burst knock retard (i.e. predicted retard in anticipation of knock to avoid knock).

EXT_BTM_DMA is brake torque management retard (i.e. during power braking).

[Mr. P.]

EST_XMSN_DMA is derived from the Shift Torque Reduction tables (i.e. torque reduction via spark timing during each shift)...

Okay - that's what I thought. However, each of my Torque Reduction tables is zero'd out (upshift, downshift, and abuse) and all this EST_XMSN_DMA activity is happening during cruise - so where then in my tune is all this spark retard originating from?

- Steve.

[joecar]

Hmmm, interesting, good question.

[Mr. P.]

Here's a screenshot of what I am describing - the second purple trace (labeled TRANS RTD) moves exactly opposite/inverse to the SPARK PID. So this transmission torque reduction PID is retarding ignition timing seemingly when the vehicle is decelerating, or stopped (0-mph)! So in the larger picture I don't think it is costing me MPG or power, it's just odd to see the behavior and I was wondering what was causing it. I know the PCM has lots of logic and parameters for DFCO... is there also maybe some logic at play to modify spark when decelerating?

- Steve.

[TurboCamaro]

I have an 02 SS with a408in it that is pulling timing with EST_XMS_DMA.
I have tried a bunch of things trying to eliminate it including setting B6614 to 0 instead of max.
What am I missing.
Attached is a cal with B6614 at 0 and logs with it at 0 and maxed.
I see there is KR activity with B6614 at 0 as well will look at Burst Knock, etc and see what it is as I have my doubts it is real KR with 8 Deg of advance.


Unfortunately I am still unable to attach log or cal files to the forum so the only file visible is the error message when I try to attach the cal file. Please help.

[joecar]

The pid EST_XMSN_DMA comes from Torque Reduction in the Transmission segment.

~ posted by phone ~

[TurboCamaro]

Hi Joe
Thank you.
I have been through all of the tables in the Transmission Segment and Torque Management in the Engine Section in an effort to eliminate the EST_XMSN_DMA.
Attached is a screen shot of the Trans Segment Abuse settings that I have adjusted as well as a scrn shot of a log showing 20 deg of EST_XMSN_DMA.
Could someone please help with what to modify in order to eliminate the EST_XMSN_DMA from reducing torque.

Table B1902 seems to be missing from the calibration. Is this something that EFI Live can help out with or is there a way it can be "added".


I realize it is very difficult to help without seeing the calibration file and a log. But I can't seem to attach log or scan files to a post. Can anyone help with this or let me know where to go for assistance. Here is the error I am getting.

Thanks

[joecar]

Torque Reduction -> Abuse Mode enables when you go from P/N to D/R with substatial RPM's... this does is not what you're seeing.

Look at the tables under Torque Reduction -> Upshift.



~ posted by phone ~

[joecar]

See post #2 here: https://forum.efilive.com/showthread.php?p=38410

start at point 5.

~ posted by phone ~