VE Tuning: OL - Accel/Decel

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07-31-2025
PajoPoncho

2 Attachment(s)

VE Tuning: OL - Accel/Decel

I am tuning the VE on a 2001 Corvette that just got a cam upgrade. It keeps going into OL - Accel/Decel and shutting off fuel trims.

Question: Is there a way to force the car to stay in CL - Normal all the time so I can tune the VE with trims at higher loads and RPMs where it currently switchs to OL - Accel/Decel?

Even with Engine>Fuel>Open Loop/Base>Open Loop>STFT Open Loop = Enabled, they shut off during OL - Accel/Decel. (I turned it back off for the tune I attached).

I would normally tune using a wideband but the owner doesn't want one.

Attachment 163256
Attachment 163257
07-31-2025
bk2life

Quote:

Originally Posted by PajoPoncho

I would normally tune using a wideband but the owner doesn't want one.

this is how you tune WO is with a wideband.
Who cares what the owner wants. if youre tuning, you need the tools to do the job.
pull one o2 out, plug your WB in. Go tune.
Not much simpler than that.
07-31-2025
abc

Anytime it goes into DFCO or PE it will turn the CL off yet stick the LTFT at the last known point. If you want to see the fuel trims work during decel and acceleration you will need to turn off DFCO and PE, iirc.

I don't think I would do it that way but it could be done. You would need to be hyper vigilant about watching the NBO2 volts and I don't know how accurate the NBO2's are above .7v and below .2v. I think there is someone here that is comfortable at tuning WOT on the NBO2's as I believe they claim they know the millivolt translation to lambda. At this point I have no reason to not believe them.

I agree the best way would be to temp. install a stand alone WBO2 (or even temp. tie it into HPT for logging) for heavy load tuning.
07-31-2025
PajoPoncho

Quote:

Originally Posted by bk2life

this is how you tune WO is with a wideband.
Who cares what the owner wants. if youre tuning, you need the tools to do the job.
pull one o2 out, plug your WB in. Go tune.
Not much simpler than that.

No, there is no reason I can't tune the car at WOT with a narrowband. Its an NA V8 that can handle Stoich WOT for an hour or so while I find the new VE. Once I get them dialed it, I will make it enrich again.

There are plenty of people who tune these just fine without WBs.

Quote:

Originally Posted by abc

Anytime it goes into DFCO or PE it will turn the CL off yet stick the LTFT at the last known point. If you want to see the fuel trims work during decel and acceleration you will need to turn off DFCO and PE, iirc.

I don't think I would do it that way but it could be done. You would need to be hyper vigilant about watching the NBO2 volts and I don't know how accurate the NBO2's are above .7v and below .2v. I think there is someone here that is comfortable at tuning WOT on the NBO2's as I believe they claim they know the millivolt translation to lambda. At this point I have no reason to not believe them.

I agree the best way would be to temp. install a stand alone WBO2 (or even temp. tie it into HPT for logging) for heavy load tuning.

Thanks for the suggestion. I bet you're right, I need to disable PE. (DFCO is already disabled).

I believe the NBs should only be trusted at stoich (hence why PE should be disabled) that way I can go through all the load cells and find true VE. Then I can let it enrich accurately at WOT when VE is calculated during OL - Accel/Decel (when put the closed loop setting back to normal)

I prefer WB tuning for sure, but its an NA V8, it'll be fine without it.
07-31-2025
edcmat-l1

Quote:

Originally Posted by PajoPoncho

I prefer WB tuning for sure, but its an NA V8, it'll be fine without it.

That is a ballsy statement to make coming from someone who is here looking for help with a basic problem.

Only vehicles I'll tune without a wideband are low compression truck engines. A Vette engine has too much compression, too much timing and are beat on too much to just wing it. But hey you do you.....
07-31-2025
PajoPoncho

Quote:

Originally Posted by edcmat-l1

That is a ballsy statement to make coming from someone who is here looking for help with a basic problem.

Only vehicles I'll tune without a wideband are low compression truck engines. A Vette engine has too much compression, too much timing and are beat on too much to just wing it. But hey you do you.....

I hear ya, but beg to differ. Inexperience with a specific tool (HP Tuners) does not equate to inexperience with tuning. I typically use WinOLS and flashing tools that have no UI for tuning. Plenty of tuning experience, just not much with Gen3 LS in HP Tuners.

Thanks for guidance with this tool! I?ll let you guys know how it goes!
07-31-2025
edcmat-l1

Quote:

Originally Posted by PajoPoncho

I hear ya, but beg to differ. Inexperience with a specific tool (HP Tuners) does not equate to inexperience with tuning. I typically use WinOLS and flashing tools that have no UI for tuning. Plenty of tuning experience, just not much with Gen3 LS in HP Tuners.

Thanks for guidance with this tool! I?ll let you guys know how it goes!

The problem here is your lack of experience with the vehicle. But hey, you do you. It's only the guy's motor we're talking about.
07-31-2025
PajoPoncho

Quote:

Originally Posted by edcmat-l1

The problem here is your lack of experience with the vehicle. But hey, you do you. It's only the guy's motor we're talking about.

No, not that either, I?ve tuned LSs on standalone too. No need to worry about the safety of his motor, I?m not willing to risk breaking his engine. With that in mind I am still choosing my current method because I know it?s not dangerous.

Like I said, I appreciate the replies that answer my question. Thank you for sharing your opinions about my approach 👍🏼