Tuning for TVS with Stage 2 Cams

Ross

Goblin Guru
Congrats! The first set of tunes usually have the biggest changes. I end up doing 12 -20 tunes before I am satisfied with the MAF tune, but most of the changes are in those first few tunes.
Good call on using the last know good tune. Now you can copy over pieces and ideas of other tunes, and slowly integrate it into your tables, using the "multiply by half %" just like you do with collected tuning data.

I tried to compare your latest MAF tune to what you started with, but I don't think I have a copy of your starting tune. The tune at the start of this thread has a bunch of changes when compared to the latest tune. You willing to share your "Modified GM stage 2" tune?
 
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SACTX

Well-Known Member
This one took me 6 runs to get it within a few % through the most of it.

This is the tune that I did before. It's not correct....It's super rich. I was using my LTFT+STFT to try and tune the MAF and I think I overshot the tune because the trims were messing with the data.... The new tune is leaner across the board except for a few cells in the middle. After going through this one, I can see why trying to tune with the trims is a hard thing to do.
 

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SACTX

Well-Known Member
I should also add that I was pretty worried about tuning only the MAF with the TVS. I was worried I'd be pushing way too much air and blow it up. I've never done something like this. It was super easy though. Just go slow and slowly increase RPM's and throttle while watching the AFR error or Wideband for any super lean conditions.
 

SACTX

Well-Known Member
I got 4 good runs in yesterday to tune and I have a problem boosting now. I think it's pulling boost since it wouldn't go over 12PSI (~26AMF). I'm working on figuring out what happened there. It boosted up to 19PSI (~33AMF) when I was MAF tuning. I did get a bunch of good data anyway, just not on the top end of the graph.

I do have I have a question. If we get the MAF tuned to where it needs to be, what is the point of tuning the VE table. The car runs trims all the time and adjusts them constantly. Wouldn't the trims take care of that? Is the idea just to get it as close as possible to keep the computer from having to make many changes? As soon as the weather changes, the computer will have to jump in and adjust trims to keep everything in line. I'm just curious.
 

ctuinstra

Goblin Guru
The VE table is actually the base table for how the car runs. If you get that spot on, you could actually run the car solely off of the VE tables, and some cars do. And if the MAF should fail, the car will run off of the VE tables. Hence when you set the car up for tuning you cause the MAF to fail by setting the fail point so low. The MAF measures the airmass going into the engine and is more accurate most of the time for calculating the fueling. However at high air velocities, the accuracy drops off. Also when you stab the throttle, the air hasn’t had a chance to rush in yet, so other parameters come into play.

Yes the STFT and the LTFT do compensate for wrong A/F ratios but they are reactive. Your best to start with a close as possible tune and let the trims just fine-tune from there as altitude and temps change requirements.
 

Ross

Goblin Guru
Is your engine reducing boost when in MAF tuning open loop mode? I wonder if you put it back in closed loop, if the problem goes away. Maybe it was something you did when putting it in open loop mode.
VE calculations are more accurate (and given more priority) when making sudden changes in throttle, and higher engine RPM.
 

SACTX

Well-Known Member
It wasn't doing it when I had Dynamic disabled. On the MAF only, I was able to boost up to about where I expected it to. It started yesterday when I went to start to tune the VE table yesterday. I'm not using the method on Goat Rope Garage, failing the MAF, I'm using the LTFT+STFT method that HP Tuners has in their tutorial. It's a slower process but I feel more comfortable that way.

To get there, I went back and put everything back the way it was on the GM Stage 2 Tune on the Dynamic tab (so it'll be in Dynamic mode all the time), added 10% to the VE table for safety, kept DFCO off, and went on my way. I looked back and everything under torque management was not messed with.

This is the tune I was using after the first run was applied.
 

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Ross

Goblin Guru
Will you be using 1 gear boost reduction on your tune ?
HP Tuners has gear information, but it doesn't work for my manual 2006 SC LSJ. I think it is for the automatic transmission, as most ECUs limit the torque during shifts. So basically there is no boost by gear using HP Tuners. I hope to use an independent boost controller that takes input from the transmission for 1st gear boost control.
 

Zoom Zoom

Goblin Guru
I noticed when Lonny posted about off the ranch goblin in classified when the guy was trying to sell that goblin . That he listed his tune was set at no 1st gear boost reduction . I also have the Z54 turbo and ZZP will be doing a remote tune for my goblin. The hp tuners and laptop should be here Wednesday so I was going to set it like he did .
 

Ross

Goblin Guru
The HP tuners tune has a place to limit torque in first gear and limit torque in all other gears.
Yes that is in HP Tuners. Does not work on my manual LSJ. I think it is only for the automatic cars. Does it work for you?
 

SACTX

Well-Known Member
I haven’t tried it. I set everything to not limit boost. I might try it one time in my tuning efforts to see if limiting boost changes anything.
 

ccannx

Goblin Guru
So the SAC TVS tune file is yours? Are you currently working on tuning the MAF tuning? Why don't you want to allow for the VE tables? You will run out of MAF during boost. It's not uncommon to go the other way and run only off of the VE tables (once you get those set).

This tune is set up for BRFS, but you currently don't have one???

Did you want to turn off the ETC? Or just follow what ZZP does to trick everyone into thinking the tune just made the care more responsive. I tend to have a strong opinion on this one. May be I'm just a fool here.

If you are not currently MAF tuning, why not turn DFCO back on? Why have it off?
I've read somewhere that DFCO can cause the jerking that so many are experiencing. Mine was shut off in the ZZP tune and the car is very smooth, it does look like they only tuned the MAF because all the VE tables look the same.
 

Ross

Goblin Guru
I put a camera on my supercharger bypass valve, and discovered that the jerkyness in 1st and 2nd gear coincides with the opening and closing of the bypass valve. This problem only exists on our supercharged cars.
 

ccannx

Goblin Guru
I put a camera on my supercharger bypass valve, and discovered that the jerkyness in 1st and 2nd gear coincides with the opening and closing of the bypass valve. This problem only exists on our supercharged cars.
It definitely went away with the turbo kit but it did get better with the dyno tune and new bypass valve.

I need to read up on it more but there are RPM and MAP exit points for DFCO Chris (not me) from HP tuners said :
(DFCO is a fuel cutoff. ie. zero fuel Engine braking will be greater when in DFCO. There are RPM and MAP exit points for DFCO, that is the jerk you feel when it renables fuel. )HERE
 

ctuinstra

Goblin Guru
It’s hard to pin down the exact cause of the jerkyness because everything the ECU controls is affected by it. I’m my data log, the timing was jumping all over the place. So the question for everything is it the chicken or the egg? It is the cause or an reaction to it? All I know, is a good tune took care of it for me. And I’m a firm believer of just doing a good tune from start to finish. Anything else is a short cut hoping to mask it. Our car is so drivable now compared to what it once was, it’s night and day.
 
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