OBeer-WAN-Kenobi

Hi All,

I've been struggling with an issue that I can't figure out for a couple weeks now. My truck shifts great and pulls very well under less than 60% throttle or maybe at less than around 4,000 RPM. The problem is that when I try a WOT run it will hold back at around 4200 RPM so It won't reach my shift points. It will do this in first or second gear for sure and you can see it in the log I've attached. The delivered engine torque just goes completely flat. I've posted on the HPTuners forum to no avail and was hoping someone here might have run into this issue.

The feeling is like being held back by a bungee cord or like trying to break though a balloon. It doesn't seem to be dropping timing, at least by what I've logged. In fact, I've effectively disabled Burst Knock Retard in my latest attempts just to test if it got better since I saw some BKR in that area. I'm not seeing any knock and I'm running at 11 degrees base.

This doesn't seem like a mechanical issue but I haven't been able to fix it with anything I've done with the tune yet.

Below you'll find the build and an attached log file. I'm also attaching a tune but it's not my most current (BKR is still enabled and other small stuff). The same issue is there in both that tune and my current so it shouldn't matter.

I'd really appreciate some insight on this. I just don't know where to turn with it at the moment.

Thanks!

Here are the specifics of the build:

01 GMC Sierra 2500HD 2WD
LQ4 6.0 L engine
Swapped from P01 PCM to P59 PCM
HPTuners Custom OS 3Bar Speed Density.
MAF Deleted
PAC 1218 Valve Springs
Siemens Deka 80lb injectors
Flex Fuel Sensor
Walbro 450lph in-tank fuel pump.
Stock feed and return lines.
VS Racing 78/76 T4 Turbo
44MM Wastegate plumbed back into the exhaust post turbo.
FMIC
Log manifold for the hot side made from flipped drivers side manifold.
2" crossover from drivers side to passenger side.
AEM Wideband
AEM Tru-Boost boost controller.

4L80e transmission
Transgo HD2 Shift Kit
Circle D 2900 RPM Stall Converter

11.5" AAM 3.73 ratio G80 optioned Rear
265/75/R16 tires

Stock exhaust minus the CAT

joecar

Are you getting any DTC's...?

joecar

hmmm, just after timestamp 19:09:42, INJ(ms) drops sharply while TPS is constant at 100%... sounds like fuel is being intentionally cut for a moment...

OBeer-WAN-Kenobi

Thanks, I appreciate you having a look at this.

Only DTCs are from failing the MAF.

As for the injector duty cutting, I noticed that too, in fact, I have another log where the INJ duty cut more severely and started to lean things out. I'm not sure what would cause this.

​​​​It almost seems like the PCM is seeing something it doesn't like and first tries some sort of torque management and then cuts fuel when that doesn't work.

This is my first time tuning so there could be something obvious I've missed but I'm really scratching my head.

joecar

Yes, I agree, the PCM is reducing fuel/torque in response to something that is not good or exceeds some sanity table...

Look in the Engine Diag section at each of the sanity tables, carefully read the descriptions and see if one of those might be causing it.

OBeer-WAN-Kenobi

I've looked over my tables so many times that my eyes are crossed. I've compared it to other tunes with similar setups that are known to be good, albeit with different OS's. I really can't find what it might be.

I've build another file (using the same OS) from another vehicle that I happen to have and came up with the same issue.

I've sent an email with my tune and log to HPTuners support to ask them to compare my OS's tables that I can't see against another OS that works. Hopefully they'll do that for me.

My last resort will be to license another OS and try that one. One of Matt Happel's or something.


ETA: I think I forgot to mention that the engine and diagnostic sections were swapped in from a 5.3L Yukon to gain flex fuel capability. Everything was then compared and copied over from the 6.0L tables.

joecar

Maybe try copying the Engine segment also (and then repopulating it with your actual values).

OBeer-WAN-Kenobi

Sorry if I wasn't clear. That is what I've done.

joecar

ah I see (sometimes I can't read).

OBeer-WAN-Kenobi

So,
It seems to do this whenever it crosses 1.2 Cylinder Airmass. I believe it is a direct correlation. Does that help anyone figure this out? 1.2 Cylinder Airmass would be the maximum my timing table goes up to. Do I need to scale something?

subeone

iTrader: (5)

seems like its pig rich.. .68 lambda at some points at less than 14 psi.. remove about 15 percent fuel around the 170kpa to 200 kpa rpm portion of the VE..should feel much better.

Here i edited your tune file.. leaned it out in some spots.. try going wot and see if it feels better.

OBeer-WAN-Kenobi

Hi subeone,
Thanks for checking into this. I'll give your idea a try. It didn't occur to me that being rich would cause the issue so I left it like that to be safe while I tried to figure it out. I'm running about E30 at the moment and took a log this morning on the way to work. It actually tends a little leaner on E than on Gas but still about 10% rich.

I do have a new tune file I'm working on that I'll post a little later. The new one was hex edited to be flex with the 6.0L from the start to eliminate the possibility of the segment swap causing any problems. It's also cleaned up a bit to get rid of all the changes I had made that didn't work to fix the issue. The issue remains however, so it wasn't the swap that caused it.

I'll look at the file you posted, compare it to my current one, make the adjustments and post a new updated file.

Thanks!

subeone

iTrader: (5)

its not an OS problem. Its just too rich it seems. Report back.

OBeer-WAN-Kenobi

Cesar......if you were here right now you'd have run from my attempt to kiss you.

So, I'm guessing the torque flatline is a red herring created by the "delivered torque" parameter maxing out? Maybe it's based on the Timing tables which max out at 1.2g Airmass so everytime I crossed 1.2 it flatlined?



This has been a pain in my *** for weeks! Thankfully you saw what no one else did! I really appreciate it. Now I can get to the rest of the tuning! I might have to bug you again next time I'm stumped.

I still haven't made the latest adjustments from the attached log to the attached file. I'll do that and see if I can mess around a little more yet tonight but it sprinkled and I started blowing the tires off.

subeone

iTrader: (5)

at first i thought you had me on facebook for a second lol (lot of ppl ask me tuning related questions) but then saw my avatar and figured out how you knew my name.

and glad that fixed it, your VE needs alot of work, make sure to use the smoothing features. It is still rich in some spots from what i saw in the new log, but seems to progress much smoother now.

ignore the torque output, that is not accurate at all. But yes, its "maxed out" so itll just flatline.

Your spark tables max out at 1.2, but the pcm keeps reading above that (you can see in the log you hit 1.5 g in some spots) make sure to remove a degree or 2 at peak torque (4-5k rpm)

OBeer-WAN-Kenobi

Thanks again,

Yeah, I need to work on the VE quite a bit yet. I've just started experimenting with the interpolation functions and will mess with the smoothing feature later. I was just more focused on fixing that issue. I really need to get it on a dyno so I can hit points more accurately and not worry about....uhm... chupacabras crossing the road.

I added the derived torque to the log specifically to try to troubleshoot this issue and it seems that was a terrible idea. LOL. It actually screwed me up worse by sending me on a wild goose chase.

I put another 10 gallons of E85 in this evening and am around 45% ethanol at the moment. I've noticed it wants to hunt for RPM at idle now so I have to find why it changed. I'm guessing the E has something to do with it.

I also have to figure out why it goes super rich (10.0 adjusted AFR or so) when I completely let off the throttle at speeds above 25mph. As soon as I get below around 900 RPM it goes back to a more normal AFR. This has been happening the whole time. I just haven't messed with it as I had bigger fish to fry.

I knew your name from an email or some other thread and I figured it was OK to use it since it's in your avatar, otherwise I'd have kept it on the D&L.

Anyway, thanks to you, I'm now back on track with my first tuning experience and feeling a lot better about it as well.

subeone

iTrader: (5)

you're welcome OB

yea i suggest using the smoothing feature over the interpolation, and a dyno is always a good idea. And yea, that torque PID really deceived you into thinking it was another issue.

I'm sure its just lean, thats why it is hunting.

More than likely it goes super rich whenever you let off the throttle because it needs more fine tuning, watch your pulsewidth whenever that happens, and if it doesnt go below a certain number no matter how much fuel you pull, then you will have to lower the min. pulsewidth table.

Ah yes, I remember now, in the flex fuel thread right?

No problem, im glad to help. Make sure to shift it higher btw, around 6k. I've tuned dozens of setups similar to yours.

joecar

So the problem was due to overfueling...? Good job

OBeer-WAN-Kenobi

I've richened the mixture in the idle area of the VE to see if it stops hunting. I've also leaned it out on the bottom rung of the VE table to try to fix it when I let off the throttle. I'll give it a try on the way home from work. It actually did require me to lower the min pulse width when I was tuning it to idle when I started it for the first time so I think I can get low enough now with VE only.

I hadn't adjusted the bottom rung in the table before because when I revved in neutral, I was actually a little lean, however, my monkey brain just didn't realize for some reason that the bottom rung on the VE table only get's hit on deceleration. Now that I've got that through my thick head I should be able to get it closer.

Yup, the flex-fuel thread. On that note, I still haven't adjusted my fuel gauge to read properly with the P59 yet. It works, just won't go all the way to F and has about 10 gallons left when it's on E. Do you have an easy procedure for that which doesn't involve reflashing over and over with different fuel levels? My oil pressure gauge doesn't seem to work anymore and neither does my transmission temperature gauge. Not sure if it's related to the PCM swap or if they just happened to give up the ghost at the same time. Coincidences already burned me once!

As far as shifting goes, do you recommend just changing the shift RPM and leaving the MPH alone? That seems to be what others have done. I realize it has to hit both to shift.

Yup. I guess you can have too much of a good thing!