Timing Blips, Shudders at Speed... Caused by What?

[squeeler642]

Had to restart the scanner as it quit logging mid-commute. Think my OBDII port is wearing out. Is there an easy fix for that? �� Got some knock in there a couple times... but MAN is this tune smooth now. Its like a totally different truck.

[SiriusC1024]

Good. I was hoping to find KR on this or the next. Being dished pistons, I'd question the knock sensors if not.

Spark lowered, MAF adjusted. Let's see one more to verify before putting it back in MAF/VE dynamic.

I'm happy that you're liking the tune. Told you there was a lot off, and I'm glad you stuck with it. Hope you've learned about the process.

[SiriusC1024]

They sell new OBD ports if you think it's a pin contact problem. Might try spraying some deoxit up in there.

[squeeler642]

Latest log attached. Feels really good but still got into knock a couple places. What do we do about that? Thinking the spark table is RPM vs MAP, so if it were me adjusting it I would look at the areas where those knocks happened and adjust in that area. Looked like the adjustments you made were really just in the bottom right corner (high RPM and MAP) of the spark table. Unless I missed something?

Also was wondering... how can we make the idle a little more spicy? and is there any associated drawback to that?

[SiriusC1024]

Did you recently get gas?

[squeeler642]

Did you recently get gas?

Nope. Same tank since Saturday. Still about a third of a tank left.

[SiriusC1024]

Great then I dumbassed it. Hold on.

[SiriusC1024]

Ok run this. A little KR is good to see. I've got Hi and Lo set to be the same to force timing right now and get an idea where knock occurs. Afterward, Lo will be restored. When KR is detected Knock Learn will adjust between the two.

Don't you have the default Spark Retard table listed? That shows where knock occurs.

I will note that I've used the knock sensor values from an LQ4 on this tune. They'll be a lot closer to what you have than the 5.3 setup that was on there. Plus someone had really increased knock recovery rate.

As far as rough idle, I gave it some extra spark correction. I was going to worry about the fine-tuning stuff after MAF and main spark was done.

[squeeler642]

Last night and today's logs. Didn't have time to look at them much...

Making a table for spark retard would just be the same table as most of the others, right? KR as a function of MAP and RPM?

[SiriusC1024]

The table for KR should've been part of the default configuration. If not, then here's how to configure:
KR.png

MAF is done now. Dynamic Airflow settings restored to default, with high RPM disable set to 4000rpm. We can fine-tune as we go. Anything else in particular? More aggressive idle? I think shift points could use adjustment.

Clear fuel trims one more time, but after that it's not necessary anymore. Drive and log as needed.

[squeeler642]

Your explanations of the MAF tuning and tables was excellent. Perfectly explains the differences I saw in the MAF freq table, and everything iterated and got closer to 0 error the further along we got thru the logs. I went thru and applied my own changes given the logs and the methods you described. Pretty cool and I came up with similar results, except I saw some slight lowering of the upper end of the MAF curve. Couldn't find any of my logs that actually got data from anywhere up that high, although I could be wrong. Is there any reason you would do that specifically?

Some questions I have after looking thru your most recent edits after the last MAF revision.

• What is the difference between Low and High Octane Spark tables?
• I assume there are different entry conditions for each of those tables. What are they? Why the difference?
• In the last few revisions of the tune, I've seen little to no change in either spark table except the hi-MAP/hi-RPM range. Saw a step change this time around. Any reason for that?
• Seems like a higher number in a cell of the spark tables indicate spark ignites earlier in the ignition cycle, at/around TDC... Does a positive cell value in the KR table indicate that number being added to that cell in the spark table, to delay ignition into a safer range when it senses knock? Is the number in the spark tables relative to TDC, and - means earlier before TDC and + means after?
• What is Burst Knock, and why are there seperate tables for it in the tune?
• What is dynamic airflow, and what params are we tuning in this step?

Thanks again for all the help. Seriously.

[SiriusC1024]

- I applied a difference of 9 degrees to the high load regions then interpolated with the smoothing function. This method gets similar results to the spark tables of an LQ4 (2003 Silverado 2500), but it retains the surface contour that is based on KR for your build.
- Spark is scaled between the two tables based on knock learn. When knock is detected spark advance is lowered. It's slowly incremented back upward until knock is detected again. Eventually this is saved as a learned value, but it's occasionally re-evaluated.
- That's where knock was occurring. Changes have been based on where the KR table shows knock has occurred. It wasn't a step change. I lowered values based on the last log then smoothed by hand across to make that shape. Took about 20 minutes.
- The numbers in the spark table are spark advance. That means it fires that many degrees before TDC, or as the piston is moving upward on the compression stroke. Positive value in the KR cell is how much spark is being removed, or spark retard.
- Burst Knock is a preemptive KR that triggers during rapid changes in the throttle to WOT. It happens whether or not KR is actually registered. I turned it off. We'll see if there is any or not next round.
- What is dynamic airflow? https://forum.hptuners.com/showthrea...ynamic-airflow

[squeeler642]

Log from this morning, with lots of knock up past 3,600rpm. I'm gonna take a whack at modifying the timing table to see how close I can get to whatever you come up with on this.

[SiriusC1024]

Probably end up around 14-15 instead of 18.

Keep in mind it's common practice to slightly desensitize the knock sensors. When I changed all the sensitivities to a Silverado 2500 is when the knock started to show up a lot worse. You have that option, but do it a sane amount.

[SiriusC1024]

That's actually looking a lot like Burst Retard. Since that's disabled it's real. Notice how KR occurs with a rapid throttle transition.

Instead of adjusting the Main tables, I would try increasing the Knock Sensor Level vs Tip In TPS table to 14 across, 13 for Tip In RPM, and see what that does for you.

[SiriusC1024]

Fuel trims should be tightened up at the top end. If you read the DynAir thread you'll understand what High RPM disable means. Filtered MAF is used exclusively above that rpm. Remember before how that value was set for MAF tuning? %-half then make it fit.

[edcmat-l1]

C5 Z06 knock sensor settings.

[squeeler642]

Understood on the KR being real due to burst KR being disabled. I think I would rather just get knock back into "closer to none" range (a couple degrees?) with stock sensor gain settings. Would I be OK to leave the timing table where a little bit of knock is still detected during regular driving, or is the goal to completely eliminate it for a safe (daily driver) tune?

I took a whack at the high octane table in the attached. Let me know what you think. Should I just leave the low-octane table alone?

[edcmat-l1]

What's the parts combo? Compression? Spark plugs? Age of the engine? Catch can? Proper PCV setup? Most of the time knock retard should be addressed by something other than tooning.

[squeeler642]

What's the parts combo? Compression? Spark plugs? Age of the engine? Catch can? Proper PCV setup? Most of the time knock retard should be addressed by something other than tooning.

Freshly rebuilt 6.0L LQ4 w/mild cam, about 25,000 miles on the clock. Mostly daily-driven highway miles. Compression spec is 9.5:1 w/NGK #739-3186 (.040") plugs. PCV setup is factory, which runs a hose into the back of the throttle body. Figured I'm not really going after enough power to need an aftermarket can setup. Still on a stock 4L60E.