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Timing changing, not sure why

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Old 09-12-2017, 01:34 AM   #1
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Default Timing changing, not sure why

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
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Old 09-12-2017, 07:51 AM   #2
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probably going to need to read the tune file. At least post a graph of the timing map if you don't post the tune?

I don't have enough experience yet and the HPtuner is so full of misc. settings that just looking at a log is only a small part of a large story.
I do find it curious that it says pressure is 5.x psi in one place and 9psi in another place though. I don't run a maf so I am not sure how that works for you.
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Old 09-12-2017, 08:07 AM   #3
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post up your tune. a lot is effected with timing/spark advance.
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Old 09-12-2017, 06:12 PM   #4
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Sorry guys. I thought I did check all of the timing variables but I could have missed some. I played w/ the idle table even though it shouldn't be in them in this area I did notice noticeably lower total timing in histograms in engine loads/rpm the idle table should not affect. So I would LOVE an explanation how the idle spark table integrates w/ the main timing table. I would also love to know if someone could show me where the heck this timing is coming from. It cannot be from the idle table I don't think but i'd enjoy input on that.

From my investigation:

IAT correction at these temps is all 0s
ECT correction at operating temps are all 0s
No EGR so those are all 0s
AFR correction all 0s
"should not' be in idle tables here?


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Originally Posted by kingtal0n View Post
probably going to need to read the tune file. At least post a graph of the timing map if you don't post the tune?

I don't have enough experience yet and the HPtuner is so full of misc. settings that just looking at a log is only a small part of a large story.
I do find it curious that it says pressure is 5.x psi in one place and 9psi in another place though. I don't run a maf so I am not sure how that works for you.

I think I can change the value of that vacuum to InHg
The vacuum is in PSI so 9 psi of vacuum is 18.32 inches of mercury but I'm not sure where it is referenced.

The MAP value is based on barometric pressure. So at WOT it should be about what the barometric pressure is at your altitude. So for me at sea level my N/A MAP value is ~13.8psi or 28.1 InHg. Although my current Baro is 29.9 at WOT i'm still seeing 1" of vacuum so combining the 13.8psi MAP with the 1psi of manifold vacuum that's 14.8 psi or ~30" of baro pressure.
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Old 09-12-2017, 08:22 PM   #5
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A/C on? Mine does that when the a/c clutch goes on and off
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Old 09-12-2017, 08:26 PM   #6
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Negative. However is there some table for AC spark interaction aside from the "AC bump Tq Spark" enable/disable?

Dave
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Old 09-12-2017, 09:45 PM   #7
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Not that I know of. My only other thought and it's hard to see on the screen shot, is it shifting when it's pulling timing? Could be torque management then
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Old 09-12-2017, 09:55 PM   #8
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Not that I know of. My only other thought and it's hard to see on the screen shot, is it shifting when it's pulling timing? Could be torque management then
Nope not shifting. The hpl is in the post but it is a steady tps/rpm which is why i'm asking others to see what I'm missing.

Dave
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Old 09-12-2017, 10:30 PM   #9
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I see that on my 04 Silverado when cruising at interstate speed with the cruise on. I've never dug into it much to figure out what causes it. I've noticed the low timing only registers on the table and chart display but not in the histogram and is very regular going by the time stamps in the log. It is a completely stock truck with just E fans, 160 T-stat and a tune. I've never seen it logging either one of my f-bodies.
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Old 09-12-2017, 10:42 PM   #10
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hey I can see it now that I'm on my laptop, was on phone. I'm no tuning expert but don't see anything that stands out. I would log all the separate spark channels, base advance, coolant advance, TM advance, ect.. that should help tell what is making it want to pull timing
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Old 09-12-2017, 11:01 PM   #11
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Quote:
Originally Posted by 2xLS1 View Post
I see that on my 04 Silverado when cruising at interstate speed with the cruise on. I've never dug into it much to figure out what causes it. I've noticed the low timing only registers on the table and chart display but not in the histogram and is very regular going by the time stamps in the log. It is a completely stock truck with just E fans, 160 T-stat and a tune. I've never seen it logging either one of my f-bodies.
You're showing average btw, so i'm sure the histogram is seeing it.

Dave
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Old 09-12-2017, 11:04 PM   #12
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Quote:
Originally Posted by dmaxs10 View Post
hey I can see it now that I'm on my laptop, was on phone. I'm no tuning expert but don't see anything that stands out. I would log all the separate spark channels, base advance, coolant advance, TM advance, ect.. that should help tell what is making it want to pull timing
If you look at the tune there is no way based on the criteria that this occurred on that any other variable should be adding timing from what I can tell. I'm just hoping someone has a pearl of wisdom for me as I don't know how often this happens and it'd be annoying to just create a timing adder channel config but I suppose I could if nobody sees anything I don't.

Hopefully someone can shed some light on this idle spark table as I have a sneaking suspicion this may have something to do w/ it.

Did I miss any possible timing adders LOL?

Dave
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Old 09-12-2017, 11:13 PM   #13
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Quote:
Originally Posted by TT_Vert View Post
You're showing average btw, so i'm sure the histogram is seeing it.

Dave
You're right on that. Your pic shows 1 drop out. Are you seeing the regularity that I'm seeing on my truck? Weird thing is I have other logs cruising at 70 where it doesn't do it.
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Old 09-12-2017, 11:53 PM   #14
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Not nearly as often as you. I'd never paid attention to it to be honest until I started getting KR recently. I just went through two long logs and only see one occurrence. Maybe I'll just not worry about it as of now.

Would still love idle timing table info if anyone has it.

Dave

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Old 09-13-2017, 09:23 AM   #15
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Just as an aside I am not sure how you wound up with 40*~ at 1200-1800rpm but that is too much timing too early usually. Most engines tolerate max timing around 2400-2800rpm, but not much sooner. Did you change any of the knock sensor settings, or any engine internals, or anything to do with the knock? Using 93 octane?
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Old 09-13-2017, 09:24 AM   #16
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not at home so I'm not on my home laptop but is your max spark table the same as your low spark table?
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Old 09-13-2017, 11:50 AM   #17
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Just as an aside I am not sure how you wound up with 40*~ at 1200-1800rpm but that is too much timing too early usually. Most engines tolerate max timing around 2400-2800rpm, but not much sooner. Did you change any of the knock sensor settings, or any engine internals, or anything to do with the knock? Using 93 octane?
I just manipulated the stock timing curve for my car. I have included the stock high octane table for my car and you'll see it's mid 30s to low 40s at low cylinder pressure/rpm.

Always run 93 octane. The internals are stock (LS6 shortblock not that it matters), no knock settings other than decay rate have been changed. Running 11:1 and about a .040" quench. The car always feels great and has amazing low RPM torque. I've played w/ the timing tables both at the track and on the street (Never a dyno) and it just feels great where it is. But I basically started w/ adding 4 degrees and pulling timing out in certain problem areas. I did that about 10 years ago and never really touched it again. That was when tuning of these things wasn't as solidly defined as it is today but it seemed to work and I certainly can't argue w/ the track performance, street performance, fuel efficiency or driveability.

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not at home so I'm not on my home laptop but is your max spark table the same as your low spark table?
Do you mean high octane vs. low octane? if so, no. My low octane table is exactly 4 degrees lower than my high octane table. However my KLF is at 1.00 so it's always in the full octane table. When I do get KR it'll once and a while get down to .99 but right back up to 1.00 in a few frames.
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Old 09-13-2017, 12:01 PM   #18
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yea sorry brainfart, high and low octane. a few ppl have done, I myself, is copy the high octane into the low octane table. the low octane table gets used if the pcm detects consistent KR and reverts to that table (usually bad gas or lower than 92 octane). see if that helps in eliminating the timing drop.

also how much of a drop are you seeing? for example, is it going from average of 35* then suddenly dropping down to 20*?
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Old 09-13-2017, 12:05 PM   #19
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The only time it'll go into the Low octane table is if the KLF (Knock learn factor) is anything other than 1.0 then it's a point in between based on KLF. IE, lets say you have a KLF of .50 and you're HOT is 40 and your LOT is 36, you'll see 38 degrees (Directly at 50% of those two tables). In this instance it was a 12 degree reduction . Certainly nothing in the LOT would be even close to that BUT the idle table would be. The idle table at that particular cylinder volume/rpm is ~29 degrees and I'm seeing the drop from ~40 to ~29 so I really think it's pulling from that idle table but I would really like some info as to why it's in that table (What criteria am I not seeing that is pulling timing data from the idle table) vs. the HOT here.

Dave
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Old 09-13-2017, 03:06 PM   #20
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The way i understand it, be it not very well, the PCM uses the idle tables when vehicle speed is 0 mph. If its not 0 mph its in hot or lot.

Why not copy the HOT table to the idle table and see what happens?
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