Can't increase timing while brake stalling (tune and log attached)

[thunder550]

I'm trying to bump up my timing while brake stalling. I'm commanding 30 degrees at .64 g/cyl and 2400 RPM in both my high and low octane spark tables, but my base spark PID and timing advance PID are both only showing 25 degrees. It doesn't seem to matter what I command at that point (.64/2400), I always get right around 25*. Can someone take a look at my log and tune and see if you can figure out what's up?

The log file is long - take a look right around frame 2640, that's where I stalled it up.

[5.7ute]

I am only new to this so I could be way wrong. One thing I noticed in your tune is that brake stalling will cause you to go into abuse mode from tables D2001,D2002 & D2003.
Brake torque management is off so that shouldnt be the issue.
Why dont you do a log with some of the other spark pids selected. This will pinpoint which parameter is removing the spark.

[thunder550]

I did some logging with all the spark PIDs selected and nothing was showing any timing being pulled. I'll check out the abuse mode thing, I thought I found all the places to turn it off but apparently I missed some. Thanks for the reply :)

[thunder550]

Well that didn't fix it :(

[Delco]

Have a look at your B5932 , as you have no speed input yet the spark is still in Base spark.

I havent looked at your tune but that is generally what I would be looking at as the vehicle will be using this table until the speed and tps values are met.

[5.7ute]

His base spark table commands 35deg at this point so that isnt the issue.

[kbracing96]

Chris, can you use the bi-direction controls to add timing there?

[thunder550]

I tried and the log didn't show any increase.

[dc_justin]

Perhaps this is a case of the hidden "run-launch spark modifier" table kicking in that Jesse has mentioned in the past...

[XLR8NSS]

Could it be Burst knock retard(B6212). It is programmed to take 6 degrees of timing out at 2400rpm if it kicks in from a sudden change in cylinder air mass and it looks like you're getting right around 6 degrees taken out.

[dc_justin]

Could it be Burst knock retard(B6212). It is programmed to take 6 degrees of timing out at 2400rpm if it kicks in from a sudden change in cylinder air mass and it looks like you're getting right around 6 degrees taken out.

There isn't a sudden change of air mass though...

One thing I noticed and posted on PT.net... he's using DYNCYLAIR_DMA as his airmass PID, but his MAF is not disabled. If his VE table does not match up with his MAF calibration, then it's quite possible that his airmass is being incorrectly reported.

GM.DYNCYLAIR_DMA is incorrectly shown as the PID for spark reference in the tuning tool. This (http://www.marketitright.com/ss/tuning/dyncylair.gif) link here will show a screenshot that proves this. I went back to running a 1 bar MAF for a while but still boosted. As you can see, GM.DYNCYLAIR_DMA is flatlined, yet timing follows the change in DYNCYLAIR and CYLAIR_DMA.

[XLR8NSS]

There isn't a sudden change of air mass though...


Yeah, I saw that so I don't think it is the cause, just throwing it out there.


One thing I noticed and posted on PT.net... he's using DYNCYLAIR_DMA as his airmass PID, but his MAF is not disabled. If his VE table does not match up with his MAF calibration, then it's quite possible that his airmass is being incorrectly reported.

GM.DYNCYLAIR_DMA is incorrectly shown as the PID for spark reference in the tuning tool. This (http://www.marketitright.com/ss/tuning/dyncylair.gif) link here will show a screenshot that proves this. I went back to running a 1 bar MAF for a while but still boosted. As you can see, GM.DYNCYLAIR_DMA is flatlined, yet timing follows the change in DYNCYLAIR and CYLAIR_DMA.

I remember you mentioning this before. Looking at the link that very well could be his problem because at higher grams/cylinder he is down around 23-25 degrees of timing.

[dc_justin]

Yeah, I saw that so I don't think it is the cause, just throwing it out there.



I remember you mentioning this before. Looking at the link that very well could be his problem because at higher grams/cylinder he is down around 23-25 degrees of timing.
:cheers:

[thunder550]

Thanks for the replies guys. I'll give that a shot :) Hopefully it's just referencing the wrong cell.

I never changed my PIDs from when I was in SD mode - just added the MAF PID to it.

[thunder550]

BINGO! I changed the airflow PID and I'm actually at .72 g/cyl instead of .64. I changed the timing in the .72/2400 cell and it worked. You guys are awesome, thanks! Oh, and an extra 2* of timing makes a hell of a difference. Still not getting any KR, so I think I can keep adding away.