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

[squeeler642]

The air mass spikes but maf and map don't move.

Where is the tune file? Nobody is looking in the file? *confused*

To me looks like either a corrupted memory or corrupted cell in the file, or a wrong value in the file somewhere like a keyboard oopsie.

I'd be reloading a stock file from known good and replacing the ECU if I saw that sort of behavior, outside of a polling interval related issue.
For example perhaps the tps or map voltage is spiking briefly that we dont see it in the log, because of a bad ground. Look at grounds. Look for freyed wires in the tps/map sensors. Look at shielded, an EMI issue with the MAP or TPS too close to some alternator wire perhaps. Sudden spike infinitesimal to see.

And you can disable the silly maf sensor to diagnose this issue. Disable that shit for diagnostic purposes. Simpler setups with fewer sensors dipping their fingers in the pool means easier to diagnose and easier to tune.

Meant to attach the tune... totally forgot. Here it is. Also just drove into work... here's the log. One good shudder at 3m25s. Hopefully in better resolution this time.

How would I go about disabling MAF? I was experimenting with MAF tuning awhile back (just for learning purposes) so I may be able to refer to some of the material I watched for that stuff. Basically commanded open loop from what i remember, and used the values I logged to modify the MAF Hz/lbs-air curve.

[SiriusC1024]

This is currently set to run in pure filtered MAF. Dynamic airflow is being entirely derived from that. What's the background on this tune and the components changed? Read off the injector part number first of all. Anything else you see that sticks out, too.

Only after that's taken care of, and settings in the tune are correct, then move on to VE.

The disabling the MAF part: Load the attached. Use Scanner>Vehicle Controls and Special Functions to clear LTFT's. Run it and post a log. The tune is set for SD. Few changes. I reduced the Low main spark table to stock for safety. RPM limits reduced in case a shift is missed, not to mention Gen III rods. Deadband added to LTFT enable.

What a hack of a tune btw. A very basic example is the file is called 6.0, but the tune shows 5.3. Shift RPM's are above the safe limit for the 4L60E. Spark exceeds MBT. All kinds of stuff. Want to get it straightened out after? Let me know.

Or if you don't want me messing with it then kick it up to the pro's:
https://forum.hptuners.com/member.php?4408-edcmat-l1
https://forum.hptuners.com/member.php?33521-GHuggins
https://forum.hptuners.com/member.php?5378-Alvin

Either way the tune needs gone through entirely. It'll solve a lot of problems, even the ones you don't know are there.

[kingtal0n]

When it happens there is an airmass spike, injector pulse spike and a timing pull. That reminds me of transient enrichment with a burst knock due to a sudden TPS or load change. Burst knock says it can pull 6 degrees I guess plus your timing table is absolute garbage with a transition from 35* to 15* from 1200rpm to 1000rpm (0.24 -> 0.36 g/cyl) which is causing alot of the shudder I am sure. 15 minus 6 puts you around ~10* which is where the spike winds up.

Here are some ideas for diag
1. Could be the tps is flicking rapidly (somebody said pull the wire). But you changed the tps already. Which means now the wiring to the ECU and inside the ECU plug itself should be looked at. Sometimes they get pushed out, the little pins in the connector can make loose connections. Or the ECU plug can be loose. Or its an EMI ISSUE


2. Perhaps the ECU is rapidly switching between maf and map suddenly. I do not know how to make an ECU stay in MAF mode and I can't tell if this happens, I never use the maf sensors for performance applications, only MAP. So I suggested disable the maf and tune map for a bit see if the issues resolves itself. Doesn't mean the maf is bad could be something in the file causing a switch from maf to map for example, tune issue.

3. Try a fresh stock new tune file and start over. Could resolve tuning related issues like #2

4. Again look for wires related to EMI like the tps wire near a high current wire. Anytime current flows in a wire it generates magnetic field which can push current through nearby wires or impede them.

5. pull on wires, push on wires, diagnostics is a hands on get the hammer


And at least,
6.
-Fix the timing map.
-Log Burst knock with enough polling interval to actually catch it
-Find out how the map was 'disabled' (forced to be in maf mode) to learn how the tuning was done

Sirius maybe can explain how it was forced into maf only mode I can't tell

[SiriusC1024]

Airflow>Dynamic>High RPM Disable set to 110rpm is how full-time filtered MAF is being used for the dynamic airflow calculation, ignoring the VE table. Factory has that at 4000rpm.

[kingtal0n]

Airflow>Dynamic>High RPM Disable set to 110rpm is how full-time filtered MAF is being used for the dynamic airflow calculation, ignoring the VE table. Factory has that at 4000rpm.

So at 4000rpm it disables the maf completely? errr disables the ve table completely?

But how does it know when to blend transient dynamic air into maf, surely this can happen anytime below 4000rpm when high rpm disable is 4000rpm, in other words maf can integrate MAP VE below 4000rpm somehow I would guess? The answer to this may lead to the issue in this thread

[squeeler642]

This is currently set to run in pure filtered MAF. Dynamic airflow is being entirely derived from that. What's the background on this tune and the components changed? Read off the injector part number first of all. Anything else you see that sticks out, too.

Only after that's taken care of, and settings in the tune are correct, then move on to VE.

The disabling the MAF part: Load the attached. Use Scanner>Vehicle Controls and Special Functions to clear LTFT's. Run it and post a log. The tune is set for SD. Few changes. I reduced the Low main spark table to stock for safety. RPM limits reduced in case a shift is missed, not to mention Gen III rods. Deadband added to LTFT enable.

What a hack of a tune btw. A very basic example is the file is called 6.0, but the tune shows 5.3. Shift RPM's are above the safe limit for the 4L60E. Spark exceeds MBT. All kinds of stuff. Want to get it straightened out after? Let me know.

Or if you don't want me messing with it then kick it up to the pro's:
https://forum.hptuners.com/member.php?4408-edcmat-l1
https://forum.hptuners.com/member.php?33521-GHuggins
https://forum.hptuners.com/member.php?5378-Alvin

Either way the tune needs gone through entirely. It'll solve a lot of problems, even the ones you don't know are there.

About to head home. Planning to load the tune you provided (looked it over earlier... you only changed the timing, right?) and log burst knock at the fastest polling rate. Will see how we do from there.

Does anyone have a factory 6.0L tune I can get for reference? I went from the old/tired 5.3L in this truck to a tune provided by my shop. Honestly, I don't know shit about tuning but am trying to learn. I had no other option than to trust the tune I got from the shop here in town. Having said that... now I have the bug. The discussion in here makes me want to completely go through the tune as you guys mentioned...

[kingtal0n]

I've been thinking about it and my best guess is there is a disconnect of the maf sensor briefly which is causing the ecu to revert to speed density for a split second. This explains this air mass spike, injector spike, and I believe the burst timing reduction as well.

I would look at
-plug of the maf
-wires of the maf
-pins at the ecu where the harness plugs into ecu, check the depth of the pin recess
-look for maf codes that show up for seemingly no reason maybe

To aid diagnosis you may
1. decrease the VE table weight at the RPM/KPA where the blip occurs, so when it happens there is less of a sudden transition in air mass
2. disable the maf for diag purposes and tune the VE table
3. log the burst knock with enough polling interval to confirm the dip is burst related

It also needs to happen
4. Fix the timing table. If you'd like I can write most of your timing table I don't mind. Or just copy an OEM table and spruce it up is prolly fine.

Beware the highest polling rate may be too high. Too much processor time. You don't need highest polling just get it up high enough, like around the rate of the RPM and timing and MAP polling is probably fine. Always use the least polling you can get away with to free up proc time and when you are done looking at specific things go back and reduce their polling for general purposes so it doesnt consume cpu.

[SiriusC1024]

So at 4000rpm it disables the maf completely? errr disables the ve table completely?

But how does it know when to blend transient dynamic air into maf, surely this can happen anytime below 4000rpm when high rpm disable is 4000rpm, in other words maf can integrate MAP VE below 4000rpm somehow I would guess? The answer to this may lead to the issue in this thread

High RPM disable is the point at which the dynamic airflow model exclusively uses filtered MAF for calcs.
Post #11
https://forum.hptuners.com/showthrea...ynamic+airflow

Below that RPM assigned, MAP, MAF, and TPS are used to define dynamic airflow. Lot of details throughout this thread. This is Gen IV stuff, but it's the same concept.
Post #61:
https://forum.hptuners.com/showthrea...-airflow/page4

[SiriusC1024]

About to head home. Planning to load the tune you provided (looked it over earlier... you only changed the timing, right?) and log burst knock at the fastest polling rate. Will see how we do from there.

Does anyone have a factory 6.0L tune I can get for reference? I went from the old/tired 5.3L in this truck to a tune provided by my shop. Honestly, I don't know shit about tuning but am trying to learn. I had no other option than to trust the tune I got from the shop here in town. Having said that... now I have the bug. The discussion in here makes me want to completely go through the tune as you guys mentioned...

The importance of displacement is so that Cylinder Airmass calcs are accurate. The spark tables are plotted along that axis.

Is this a stock 6.0? If not then a stock file will be of limited use. It'll still need tuned and end up very different.

Still would like the injector part number, please.

[squeeler642]

Commute home was uneventful. No blips on the way that I could feel, nor anything reflected in the log on my first breeze thru it moments ago. CEL was on immediately when I started up post-tune-update, but also noticed in the Engine Diag tab you had the "MAF freq fail high" value adjusted to zero, so I ignored it. Any reason for that change as well?

One other thing I failed to mention in the original post... feels like it's down on power slightly with this tune. Motor has a mild cam in it from the supplier, but it was their own spec/custom grind (or so they said) so I don't have the specs for it. I might be able to get it from the supplier if I asked... worth doing? Here's the link to the spec page on the motor, that may help a little. More than anything, I wonder if that makes the timing table make more sense? I figure maybe not the harsh transitions you guys were talking about, but some of the numbers maybe. Anyways... figured I should mention it.

Latest log, attached. Planning to look into more of the changes you guys suggested when I have a little more time.

[squeeler642]

The importance of displacement is so that Cylinder Airmass calcs are accurate. The spark tables are plotted along that axis.

Is this a stock 6.0? If not then a stock file will be of limited use. It'll still need tuned and end up very different.

Still would like the injector part number, please.

Some answers in the post above. I will take a look at the injectors. Is that something I can see easily or will I need a borescope or something to see it?

[ns158sl]

Where is the tune file? Nobody is looking in the file? *confused*

... Grasshopper you will learn someday.

OP: I would ask for the Cam specs or valve event specifically. Has nothing to do with your issues, but always nice to have, and later you can adjust EOIT. Basic duration and LSA might help the better tuners evaluate your timing and fuel tables just by that. To watch the timing clamp at 10 degrees seems like a torque management issue. I would log any kind of torque management PIDS, id offer more help on that, but i havent touched a gen 3 in about 10 years. It is seeing something it doesnt like and kills timing. I dont understand the fuel spike though. It is almost like it is going to some sort of default mode. It is going pig rich right before the timing cut. Id make sure you didnt turn off any Codes.

Could be losing signal on sensor, but a CEL should set, and/or you would see the data default to something. Everything airflow seems to match/smooth during the issue.

[SiriusC1024]

Some answers in the post above. I will take a look at the injectors. Is that something I can see easily or will I need a borescope or something to see it?

Part number will be molded into the side of each injector. CEL is on as a consequence of MAF Fail 0hz. It's set to 0 in order to fail the MAF. This invokes the VE tables exclusively, thus SD. I kept the CEL illumination checked as an indicator.

[SiriusC1024]

Yes, you're down on power. Remember, I lowered the Low main spark table for now. Low is referenced in SD mode. Airflow needs dialed in, first.

VE adjusted. Displacement set for +0.040 bore on a 6.0 block.

Here's the next. Be sure to use VCM Scanner>Vehicle Controls and Special Functions to clear LTFT's before logging.

[squeeler642]

Yes, you're down on power. Remember, I lowered the Low main spark table for now. Low is referenced in SD mode. Airflow needs dialed in, first.

VE adjusted. Displacement set for +0.040 bore on a 6.0 block.

Here's the next. Be sure to use VCM Scanner>Vehicle Controls and Special Functions to clear LTFT's before logging.

This tune felt... really safe. Haha. Took a look at the changes you made before I flashed it - wondering why the PE threshold changes, and why do we need timing tables to be broken out into base and idle advance tables? Couldn't that just be done all in the same table? Didn't compare the numbers to see how different they were now that I think of it, but am curious why we need seperate tables there. Anyways... Here's this morning's log.

Actually got rear-ended on my way in by this poor lady... the ONE time I come to a full stop at a stop sign, I pay for it. State trooper posted up near the on ramp near that stop sign on the feeder, figured I didn't want to get tagged for rolling it... and boom! No damage to either car, but she was so shaken up she was on the verge of crying and was pretty panicked. I gave her a hug and told her to pretend like it didn't happen, just pay a little more attention next time! Poor lady probably thought some thug was about to hop outta this loud, windows tinted, ghetto old Tahoe! I'll make sure to keep rolling them in the future!

[SiriusC1024]

That's a crazy story lol. Glad there were no injuries or damage.

Really need the injector part number in order to confirm the data, please.

[kingtal0n]

ur killing me with the 15 seconds stretches of 97KPA at 15.2:1 air fuel at 2400rpm 10* timing

No EGT gauge. When EGT rises enough the piston rings start to lose tension, permanently. Then it starts to burp up oil and people blame the PCV system and add a catch can.

Adjusting the VE table to hit a target in PE Is the same as adjusting VE to hit a target in closed loop. He has a wideband. So why not use PE.

Seems like a unnecessary risk to keep it closed loop at WOT. And make no mistake 97KPA is WOT.

[kingtal0n]

It's not closed loop at WOT. At true WOT it goes into PE, which is OL. The engine isn't under a lot of load in the areas you're talking about. As far as CL, VE can be extrapolated. Wideband is there to verify, but I'm not going to tune the entire VE table with it.

97KPA is max load, wide open throttle max cylinder pressure. Throttle position is not an indicator of load. Engine volumetric rate in CFM and air mass flow rate have nothing to do with cylinder pressure or VE.

The engine literally can't be under more load in the areas I am talking about than it is currently. EGT must be approaching 1600*F.

[SiriusC1024]

I have no problem using PE. Normally don't see MAP that high at 50% TPS in a performance engine. I adjusted the thresholds. Applied fueling corrections to VE.

[kingtal0n]

I have no problem using PE. Normally don't see MAP that high at 50% TPS in a performance engine. I adjusted the thresholds. Applied fueling corrections to VE.

Truck is very heavy. I know its weird. But either tell the guy hey if you see 15's on the wideband at 95KPA back off. Or set preliminary PE modes to very low throttle position and rely strictly on the KPA trigger until you sort out the vehicle weight/loading from future logs. It isn't knock you should worry about its EGT. It just goes up and up and up until something melts usually its the rings that give up first if the fuel quality can reminiscent with the compression ratio.