Good data tuning on road?

[weinerschizel]

I'm second guessing my data. Currently tuning fuel / VE Table. I collect the data on my own, as I have no assistant to watch the computer while I drive. Making it extremely hard to know if cells have stabilized.... I only use cells that have several hundred hits or more as a result.

I've been holding brakes and using throttle to hit as many cells in a column (RPM) as possible. Between balancing this and controlling the car on the highway, I wonder if I'm not introducing transients in my data. Keeping the throttle steady is really hard. Constantly question if I'm chasing my tail or not. I've done 8 data runs adjusting the VE table along the way for fuel, burnt through about 10 gallons of gas on this tune (this is my third time tuning fuel in last 2 years since my engine build).

I know a dyno would be ideal but how good can I get my tune w/o a dyno.

Also any tips on knowing when the data is reliable to adjust the VE table with?

Thanks!

[gtstorey]

Add in the latest log so people have some idea what it really looks like. And you might as well add in the tune.

[Alvin]

My recommendation is to drive it normally. Maybe avoid hopping on and off the pedal too fast too often.

[400Horses]

When driving plan your route so that it allows for time to roll on and off of the throttle easy. Sudden acceleration/deceleration causes the scan to skip cells. If you can add in to the hills into the route it will allow for more rpm to populate cells without having to worry so much on speed due to down shifting. If that isn't an option you can pull the vehicle down into a lower gear to hit higher rpms also.

[weinerschizel]

Not sure how to attach. I uploaded the whole tuning session to Google Drive, linked below:

https://drive.google.com/drive/folde...vU?usp=sharing

I make a tune say 01, log data to 01 file. Then adjust for 02 tune off 01 log. I forgot to save the baseline log file, but just tweaked idle so wasn't much. I've not run the 09 file yet. Not sure if makes a difference but running RTT OS. I'm also adjusting part throttle w/ STFT. LTFT don't work with my cam. They totally mess the fueling up.

[400Horses]

If you are doing VE tuning it is best to do it in speed density with STFT and LTFT disabled until you get the cells +/- 2%.

[weinerschizel]

So disable the STFT as well?

Confused, if I turn of STFT won't the readings be turned off too? I don't know exactly how this works.

[edcmat-l1]

So disable the STFT as well?

Confused, if I turn of STFT won't the readings be turned off too? I don't know exactly how this works.

Don't turn off the short terms. Use them to dial in both the VE and MAF. OL tuning is a waste of time. The computer doesn't care what your wideband says.

[weinerschizel]

Don't turn off the short terms. Use them to dial in both the VE and MAF. OL tuning is a waste of time. The computer doesn't care what your wideband says.

That's what I'd thought! If I turn off STFT then I cannot collect the STFT to adjust VE table. Tried Wideband for part throttle before it was terrible. Results were worse with LTFT as they seem to be too slow to adjust fuel for my cam. A tuner friend put me onto tuning with STFT instead and completely disabling the LTFT.

[weinerschizel]

If you are doing VE tuning it is best to do it in speed density with STFT and LTFT disabled until you get the cells +/- 2%.

This doesn't make since to me. There's barely enough resolution in metering system to get that kind of accuracy out of the fueling down low. At lower power & RPM in the VE table one point of adjustment in table is around 2% already. With higher quantities of fuel that seems reasonable but, idk how to consistently hit +/- 2% towards the bottom of table.

Are you tuning on a gen 3 SBC P59 PCM? Maybe the newer stuff is better?

[SiriusC1024]

Elaborate. What about it doesn't make sense? People do it that way all the time. Are you meaning the secondary VE table doesn't have resolution? Use the primary. Copy changes into secondary after you're done.

BTW hit 'Go Advanced' to attach files to your post.

[edcmat-l1]

P59s don't have a secondary VE. None of them. That's an early P01 thing. The secondary VE was gone by 2000ish.

[400Horses]

The truck I am tuning has the primary and secondary VE tables. It is the P01 PCM and I was having issues figuring out why my changes weren't working. Rabbs88 helped me and I set up my scanner to tune in speed density. I also have the LTFT + STFT VE also so it is setup for when I enable the STFT and LTFT. If you have the secondary table you have to set that as your primary table. After you adjust the tables you have to copy and paste each line in the secondary to the corresponding line in the primary table. Then interpolate between the cells that changed. Hope this helps.

[weinerschizel]

I got more figured out... Taking lots of handholding from a tuner friend. Can only rely on the narrow bands for cruise and idle. Here's what I learned...

The truck engines / VE tables are in ballpark of 12:1 AFR for WOT (higher loads and RPM on the table). They essentially have PE turned off in the tune (under the PE tab) otherwise it's baked into the VE tables.

I didn't realize the narrow band sensors won't measure accurately much outside of the idle and cruising envelope. So the STFT or LTFT can be used to tune idle and cruise under throttle inputs lower that PE threshold (when engine needs 14.7:1 AFR). In my case LTFT wouldn't work due to aftermarket cam so I went off STFT.

I didn't realize the fuel trims / narrow band O2 sensors wouldn't work at higher RPMS / flow and shouldn't have made adjustments to regions PE would otherwise create a richer mixture for if it was enabled. I had really thought the settings in the truck tune were correct for PE but in fact it was essentially turned off and I was monkeying with mixture baked into the VE table. Thankful I didn't blow the engine up.

I need to shift to the wideband now as I've got cruise and idle pretty well dialed in. I have to tune PE. I took the PE settings from my C5 corvette, copied them to my truck... Then richened the PE eq ratio and will start there.

Not sure if there's some good tutorials on tuning PE?

[NotSure]

I don't know what vehicle you are tuning, but my old Gen 3 truck I could put the trans in D2 and it would start out, and stay in, 2nd gear. This helped to hit higher load/low rpm areas on a launch. You can also temporarily program the tow/haul shifting schedule to do odd things like hold gears without downshifting to hit other hard to hit areas.