Wants to pull in gear

[epfatboy]

BK, yeah, thats basically where I'm at, I just over utilized my cut&paste skills a smidge. She starts and idles like a boss now, it's when I pull it into gear when the sadness begins ;-) but yeah no big deal at this point. This is a fresh engine build and it was the startup I stressed a bit over but it started fine and has enough run time for enough break in according to me.

Sirius,
Deatschwerks 440cc LS1 style injectors.
https://deatschwerks.com/products/18u-01-0042-8


It's a nice day, I'll go get a meaningful log and post it up with my updated tune.

[epfatboy]

Went for a 15min drive, Tune and Log included. I touched up the VE based on the log but haven't changed anything else.

It still stumbles/surges when the throttle transitions from idle, once I'm in it a bit it runs pretty smooth.

The cruise control feel is weak, it gains RPM downhill but will lose RPM eventually and slowly on the flats... so better but needs to be fixed for sure.


Any areas I should focus on would be great, I'm using stock Throttle Cracker values and can see it adding air off throttle at RPM. Also still wonder if I should re-check my braf but when I pull 3% it surges and stumbles more and if I add more it feels like the cruise control effect picks up more strength on the flats.

What to the Moving/Rolling Table do? It does not seem to help if I set it at like 800RPM and the stock value was 0?


Note, I'm working on seperating the IAT from the MAF and relocating it. This is in a '64 Nova and it stays pretty warm under the hood and is heat soaking the IAT pretty quickly.

NOVA Cammed LS2.MAFBASELINE.hpt

first drive8.hpl

[SiriusC1024]

You didn't put in the right values for Short Pulse Adder.

[epfatboy]

Hey Sirius,

I get why you think that and I checked this a bunch already, they are the right values just off by a little.

Looks like they get changed to the next valid value when you enter the data, same thing happens with the voltage table, all the entered values are a tiny bit off.

TESTING:

- When you cut/paste it from the excel spreadsheet to the tune it changes the value slightly. (example .7659 goes to .7599)
- If you type the number into the cell it does the same thing AND it lands on the same changed value as above
- If I type the number in and change it just a little it still lands on the same value. (.7657 goes to .7599)

Looks like the rounding routine from Office Space...

[SiriusC1024]

Yeah you're right. I copied the entire row like an idiot.

[epfatboy]

I?ve been screwed by invalid injector data in the past so it actually looks like I may have learned my lesson.

I probably would have been happier if you were right and the fix was that easy.

[SiriusC1024]

Ok if you excuse my dumbass moment I can still offer a few suggestions.

Go back into SD and tune the VE table. Use the narrowband fuel trims to do this. Set PE enable to 85kPa.

Lower idle to 750rpm. Make necessary changes to hold it. There's quite a bit there to do.

Experiment with decreasing throttle cracker.

[epfatboy]

Thanks for the suggestions.

I pulled 50% out of Cracker under 2800rpm, that helped the cruise but didn?t solve it. My AFR leaned out a bit when I did this as well.

Since that worked I zeroed out cracker under 2800rpm and that solved the cruise control but left it stumbling on the way down off throttle but good test to understand what happens. The AFR continued to lean out so it drove like crap but I learned something.

I?ll set the cracker values back to stock and do some work to remove air and keep it smooth. I?ll also give it a little more VE and see how it goes.

[SiriusC1024]

That's good. You'll have even better results if VE is tuned with the narrowbands. Try to get idle rpm below 800.

[epfatboy]

I'll def work on lowering the idle, just had it up to ensure I can start/drive her.

At the risk of derailing this thread I have to ask because I'd like to understand... and since your the thrid person who mentioned the NB's..

I have read a little about NB tuning and honestly it sounds just like WB tuning in that most of the effort is in setting up the scanner.

My question isn't really why the NB or WB is better it's more about how much better? Because let's face it, I'm not good at this even after 486 hours of youtube vids. And as we know those vids are all (mostly) WB examples that step you thru a high level tuning process. I also happen to be at the dragway a bit so a WB is always going to be part of my builds.

Adding another concept to an already challenging event to me seems like a bad idea but If there is a vid/writeup (something a dope can understand) on dialing in the VE with NB's I'm willing to try as some of the info I have read makes sence and I have the time.

Any decent links that explain how to use the NB's in the scanner to capture the VE offsets?

[gtstorey]

No matter what tuning you do with the wideband, if you run the vehicle in closed loop it's going to be using the narrowbands anyway so you might as well adjust it so the closed loop tuning is closer to start with.

Accuracy of aftermarket widebands may not be (probably?) as good as the narrowbands.

[edcmat-l1]

Bottom line is, your PCM doesn't care what your wideband says. Forget about wideband tuning part throttle. Forget everything you've read. Unplug your wideband until you're done part throttle tuning and are ready to wide open throttle tune it. Simple as that.

[epfatboy]

Okay well after just a bit of searching the best I came up with was using the LTFT?s to adjust the VE. That seems easy enough to understand, setup, and do. And I think that?s what a few of you guys were saying to do.

Here is the write up I found.
http://www.ls1.com/forums/showthread.php?t=46733
Goes thru a few steps in a logical order. WOT/PE tuning feels like I should still use the WB so I?ll hopefully ignore that area of the write up.

What I still don?t get is how to use the NB outputs in SD and if there is value in doing it that way versus the LTFT?s.

[SiriusC1024]

Use LTFT, STFT, and LTFT+STFT. I make corrections based on what's going on in all of those. LTFT+STFT with weighting based on what I see in the other two. You'll see.

WOT/PE yes wideband. Set PE enable to 85kPa to capture the bulk of the table as narrowband trims.

STFT and LTFT should be default to scanner. It's the same procedure as wideband - apply percentage corrections.