Timing changing, not sure why

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Sep 13, 2017 | 03:17 PM

#21

TT_Vert

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From: Elgin, Illinois

I certainly could do that but then I'd be idling at 31 degrees which I certainly don't want to do. I really need to understand this Min TPS idle setting a bit more. Mine is 1.2% yet my idle % is 5-7% which seems pretty typical for a fly by wire TB I think. I'm 100% confident I'm in the idle table at idle just by playing w/ RTT Idle table timing and seeing it take effect.

Dave

Sep 13, 2017 | 05:47 PM

#22

Lsxford

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From: Winfield AL

Quote:

Originally Posted by TT_Vert

its only going to idle in the idle cells of the table, so 400-1200 rpm 0.8-0.24 cyl air mass and there shouldnt be 31* in those cells in any of the ignition tables. The idle tables ive seen go all the way out to what 4800 rpm or something like that, where it should never idle anyway. My point being theres an idle section in the HOT which should closely resemble the idle section of you idle tables already.

This is of course unless you have a pcm unlike anything ive ever seen

Sep 13, 2017 | 05:51 PM

#23

TT_Vert

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From: Elgin, Illinois

I posted my stock timing table up above. Look at the idle cells it's at least 27° in the high-octane table.

Sep 13, 2017 | 06:04 PM

#24

Lsxford

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From: Winfield AL

Quote:

Originally Posted by TT_Vert

I posted my stock timing table up above. Look at the idle cells it's at least 27° in the high-octane table.

I see, however most of the tuning how tos ive read state to have the tables close to each other for transition smoothness. Your issue is occuring at 1800-2000 rpm. So i would copy my hot to my idle then change the idle area of the idle table to match what it was before so youre still idling at 22* or whatever but at say 2000 rpm if it changes to the idle table theres no change. Or make it 2 degrees less than your hot and see if when it dips if it goes to that number. You can always flash your current idle table back in after if its not that. But if it is that then we can dive into why in the hell would it be switching to the idle table.

Sep 13, 2017 | 06:42 PM

#25

TT_Vert

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From: Elgin, Illinois

Quote:

Originally Posted by Lsxford

RIght I do get that. Generally SOP is to copy the 400-1200 HOT to the Idle table to prevent weird transitions and i've tried it. The few problems I have with that are this:

1. If I have my HOT table the same as my Idle table I will have a fairly high idle table
2. and then from 1200 to 1600 In the idle table I have to do some signifigant smoothing. Actually my HOT table at 1200 is so much higher than my idle I really couldn't even smooth it. I'd just have to basically copy my HOT to my idle which as you say defeats the purpose of an idle table.
3. The car seems to idle better at 17 degrees than it would if in the HOT table of ~31 deg.
4. The stock idle and HOT tables are quite far separated if you compare them and a stock LS1 transitions just fine. I've not had any real issues w/ off idle transitions in parking lots, etc. I don't have the bucking either, but perhaps a larger cam would benefit more from this type of tuning.

Dave

Sep 13, 2017 | 11:38 PM

#26

subeone

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I remember a similar issue, I believe I disabled or enabled spark smoothing or something of the sort. Fixed it.

Sep 14, 2017 | 12:35 AM

#27

statesman

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Quote:

Originally Posted by TT_Vert

So i am monitoring load, rpm, ECT, TPS, etc and i have no idea why the timing is dropping and then returning in a steady cruise. Nothing leading up to this even or after changes as far as i can see. I've included the log and a screen shot of one of the examples. Perhaps someone can shed some light on this.

Thanks in advance guys

Dave

I've just looked at your log... and your TPS is changing when the timing drops. This is not a steady cruise.

Sep 14, 2017 | 12:35 AM

#28

TT_Vert

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From: Elgin, Illinois

Quote:

Originally Posted by subeone

I remember a similar issue, I believe I disabled or enabled spark smoothing or something of the sort. Fixed it.

Hmm.. What did you notice drivability wise by doing this? I'm going to research this a bit.

Dave

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Sep 14, 2017 | 12:41 AM

#29

TT_Vert

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From: Elgin, Illinois

Quote:

Originally Posted by statesman

I've just looked at your log... and your TPS is changing when the timing drops. This is not a steady cruise.

Somewhat my point. At this exact point it is going from 15-20% TPS which definitely keeps it out of the idle timing table. So looking at that area in my HOT table that's 45, 45, 44 degrees respectively based on cylinder volume and RPM. It is dropping from 45 to 28 as seen in that log where it should not be. So it's some transitional timing reduction but no idea where it is coming from. Maybe that spark smoothing spoken about above? However it oddly seems to correlate to the idle timing table for this volume vs. rpm. The GUI says this is idle spark Advance but when pressing the In drive/In park buttons it shows BASE spark so perhaps it isn't actually just idle spark despite what the HPT info says? Then they have "tumble flap" which is just confusing but is the criteria to use this idle/base spark table. I wonder if the min TPS (1.2%) is the change in TPS to come out of main table. The description in HPT is a bit confusing to me, especially since idle is 6% on my C5.

Quote:

[ECM] 2600 - Main Spark Table Select TPS: This value is the Throttle Position required to disable the Main Spark tables.

Dave

Attached Thumbnails

Timing changing, not sure why-timinig.jpg

Timing changing, not sure why-idle-timing.jpg

Last edited by TT_Vert; Sep 14, 2017 at 12:52 AM.

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