I am just started to retune my motor after the swap to a 4l80e, and I am stuck. I am running a 5.3 motor with 4l80e basic sloppy setup. The motor runs pretty good until it starts to get any boost and then it just stumbles and wont go any higher. I had the same setup last year before I switched the trans over to a 4l80 and I did not have this problem. For that reason, I do not think it is a hardware issue. It slao does not seem to be going lean, so I was thinking it is not a misfire. Any help would be greatly appreciated. I have attached my tune and a couple logs.
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Update: It now will get on boost, but stumbles a lot on the transition to boost.

Thanks,

Matt

 

It's hard to tell from the log the problem you are describing. I've watched it several times, but so far the only things I've noticed odd is that your PE seems to stay on all the time. It commands 12.56 even on decel, and low rpm and speeds. It changes commanded as it should through boost kicking in, but in a few spots you are actually hitting negative spark values on acceleration. Your VE table seems to be a bit off, as it does get rather lean at mid rpm range, and mid MAP range, basically the center of the table.

Have you considered changing your PE enable MAP to perhaps 80 or so? Or a similar number? Would help with your mileage, since it's literally in PE for the whole drive it seems. This will require going back over the VE though, obviously, but I would anyway to smooth that out a bit more IMO.

I looked to try and see when it is shifting, but it's pretty hard to tell in the log. Logging the trans current gear, TCC slip, TCC Applied and various other trans info would be helpful to see if this is a gear setting issue or and engine one. Also hard to tell because the TPS seems erratic, on and off the pedal. I understand the need to not bury the throttle though with boost, but it is really hard to see the shift points lol.

 

You're at 0.0* spark advance when boost is coming in, with a burst knock of -6.0 being registered. I'll bet this isn't helping that sluggish feeling. You can raise or disable the burst know settings and see if that helps. I saw no detected knock through the entire log, so I don't think this will be an issue turning off.

 

Also, you actually hit 29.6 on my accel rate chart, which is plum fast as F***.... That was a later stab on the throttle, but pretty damn impressive. Almost 30 mph per SECOND acceleration rate. Good lordy. It looks like spark was on a different RPM on that stab, so it was higher. That acceleration didn't occur until the spark came back off 0, which is where it started, and climbed to about 12-13 and that's when you tagged out my acceleration chart numbers... Looks like the spark table could use a little love on that valley on the left side. Move your numbers to the left a little on the bottom, and disable burst knock and see what that does for you.

 

Ah, I just noticed you have your EQ ratio table set to 1.17 across the board pretty much, which appears intentional. Now I know why it's always commanding 12.56 lol.

 

@@ChopperDoc Thanks for the feedback. two questions:

1. What are you referring to with the acceleration chart? "you actually hit 29.6 on my accel rate chart, which is plum fast as F***...."
2. What is the advantage of "changing your PE enable MAP to perhaps 80 or so?" I do not have a MAF anymore,so is this still an option?

Thanks,

Matt

 

1. It's a user math you can plug into the scanner to see how fast your vehicle accelerates. Can be useful to check drivability and to see if tuning changes made an improvement. Here is how to make it:

If you use MPH under Generic Sensors, then it should look something like this:

([50020.114.avg(-1000)]) - ([50020.114.avg(1000)])

50020.114 = Generic MPH PID on mine, individual results may vary.

1. Select "new variable" and then either the generic MPH PID or your specific vehicle one.
2. Under the "Edit PID", select "Average" and under "period" write in -1000 (it will only let you type -100, but you can add another "0" after you have it on the formula area.
3. Add a " - " symbol
4. Repeat step 1 to add in second reference frame (same MPH PID again)
5. Select "Average" for second PID and under "period" write in 1000
6. Use 3 decimal places
7. Select MPH as units.
8. Name it something awesome like "Scare factor" or something.

* note, for all PID's and units make sure you are using MPH. The PID's will normally populate with m/s which is meters/second

Should be good to go after that.


Break,

2. You are still using MAP. Without that you would not be able to run speed density. Not having a MAF doesn't affect that. Now I will say though, with you EQ ratio table set to 1.17 in all operating areas, you don't even need PE mode at all, because you are just commanding 12.56 all the time, even at idle. I don't know if you meant to do this, but it's got to be pretty tough on your gas mileage and potentially your spark plugs. I'm surprised they aren't fouling out to be honest. What I would do is set your EQ ratio table to 1.0 in cruise areas, at a minimum, or set it back to stock values. Then I would set the PE enable MAP to 80 ish, and retune the VE.