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.

[epfatboy]

Thanks a lot, that helps.

I like the idea of weighing. Feels like that would help get me to a "drivable" tune faster than waiting for LTFT to be populated.

I'll up PE engagement, give it a try, and report back.

[epfatboy]

Finally no rain so I turned on the LT/ST trims and bumped the PE to 85 kpa (MAF still disabled) and went for a 20 minute drive. Nothing came thru the LT's, if I remember right that is normal and I just need to drive the car longer.

What got my attension was the diff between AFR Error and the STFT's... I was thinking it might be off but I didn't think it would be off this far.

AFR Err
afr err.PNG

ST Err (same as st+lt)
st err.PNG

I am doing/thinking about this right?

Also that "cruise control" issue is still present, will that impact my results and should I try to filter that condition (off throttle & mph <>0) out of the results?

[epfatboy]

Yeah, I?m a dope.

I turned on fuel trims.

At least I caught it before someone else told me I?m a dope.

[bk2life]

I turned on fuel trims..

you need fuel trims and lt and st and o2s to be on

[bk2life]

Ok,
you need to tune your VE table. So you have the vehicle set up for SD. This means no input from the MAF will tell the computer to add or subtract fuel. Right now you are running on the VE table only. So, imagine you have a carb engine, and youve made a quick run and killed then engine, pulled over to the side of the reoad and pulled some plugs to see what they look like. If you are good at reading plugs, then you can imagine the VE table as 8 spark plugs. Some plugs are white as white can be. Some plugs are dark. Others are fouled.

Now it is 100% up to you on what you want to do to get all those plugs looking the same. This is where the VE table comes in. If you need it to be leaner you lower the number, richer, raise the number. These VE numbers = air volume, are are remapping the fuel table to do what you say to do.

The narrow band o2 sensors will do everything they can to make whaveter is coming down the tailpipe read stoich. 1 lmabda or 14.687.
if it reads lean, its changing the fuel trim to add fuel. Same for rrich, the o2 sensors wll tell the computer to take away.

You can tune your VE, and MAF to get near perfect fuel trims (-+3)

What the ECM can not do is add fuel when you accelerate. When the computers senses WOT it go to 'accelerate' mode and does what is programmed in the computer.
this is where the wideband O2 sensors come in. So you can log the wideband reading and see what the computer is telling it to do and then compare. From there you add or subtract the fuel trims to match, and or adjust the PE table.

Long trips of around 20 to 30 miles are best for logging. This allows everything to stabilize and give true readings. Radiator eventually gets to the operating temp, IAt's stabiliaze, exhaust is hot, they all have an effect on the fuel fuel trims.

I hope im not mansplaining, sometimes it helps to remember the basics and how it works in a FI engine.

VE first, then MAF, then timing, then recheck VE/MAF

[epfatboy]

Thanks BK, That all makes perfect sence. I know it may seem like I needed some mansplaining based on my comments but honestly I do get how some of this works, your write up confirms alot of what I have read here and other places, thanks again.

I'm figthing a cold and the weather here so I appreciate folks hanging in there with me.

Good news
I have managed to stop the car from pulling in gear
The cruise control feeling is pretty much gone as well.
I think it should decell "harder" but what I have going on now is much better.

Today I got one more a decent drive in and the VE under 3200 looks decent. I'll keep working on it and bringing the RPMS up higher as I feel more comfortable.
My drive notes:
- starts and idles in Park and Gear okay
- Surges and stumbles during rolling idle.
- under acceleration it feels good.
- light steady throttle there is a noticable surge


I'd like to tighten up the surging issues as it impacts where I drive and for how long. I was hoping a better VE would do that but so far that ain't doing it, it does feel like fueling related based on how I see the afr occilate. I also feel like it's messing up the trims when I'm off throttle and coasting but what do I know.

Anyway here is the current tune and log. Any help would be great.
NOVA Cammed LS2.PartThrottle.hpt

drive.partthrottle.hpl