Cant get auto tune to work right

[Farmtruck62]

Not sure what I am doing wrong but I auto tune is just not working right or me.

I can manually adjust VE to where it is Lambda 1.00 at idle and cells near it (14.7 on the AFR gauge and data logger) but once I engage auto tune to start working on the rest of the tune up, it wants to adjust VE cells lower effectively leaning it out. I have let it go a few times and it will go all the way out to Lambda 1.20 before I shut it off.

The VE table in Auto Tune, when you hover over cells it shows that it should be targeting and AFR of 14.7 for 80KPA and below if custom is selected and Lambda 1.00 again for 80 KPA and below if the lambda 1 table is selected. I would think that with those values auto tune should be adjusting for those values.

I have tried turning things on/off EGO Authority Table but not sure that did anything for me.


Just looking for a little guidance.

Motor is a 440" LS at 13-1 compression. It is in a sand rail and makes 550+ rwhp. Has ID1000 injectors and fuel pressure is 58 psi.

[DaveEFI]

Do you mean auto tune or VEAL?

But I don't think either is reliable at idle. I only use VEAL above 1200 RPM.

[Matt Cramer]

Do you mean auto tune or VEAL?

But I don't think either is reliable at idle. I only use VEAL above 1200 RPM.

Correct. They can tell you what will get a desired AFR target, but neither one will tell you what actual AFR will get you the best idle. Idle tuning is a bit different from off-idle tuning in that you're looking for smoothest running or pulling the most vacuum, NOT for a specific AFR.

[Farmtruck62]

I have tuned plenty of big cammed LS motors since 2003, gas and some E85. But my experience is with a stock GM computer using mostly HPtuners (was tuning with Autotap and LS1edit before HPtuners). I am very comfortable with the tuning aspect and I understand stoich for idle and part throttle is not always optimal but it is a darn good base to start at. My E85 drinking 418" LS motor likes +/-1.05 lambda at idle and cruise and it makes best power at 0.77 lambda running 9.2x @ 144mph in a 62 C10 pick up.

The issue I have is when autotune is enabled, my nice Lambda 1.00 at idle goes away with in 1 minute and then it stumbles badly as it is super lean (1.2x lambda). I am leaning towards the WB O2 sensor is refreshing too quickly in the log/autotune feature and is likely not providing an accurate AFR reading to the MS3 due to reversion. It sure looks like this is the case when looking at the log, huge AFR swings are seen.

Has anyone slowed down the O2 pick up frequency to help with this potential issue at idle?

I am planing to filter RPM threshold in the autotune section so it does not adjust anything below 2,000 rpm and scale the VE by hand in this lower RPM section. I am guessing this will help to minimize any issues at idle.


I did not get enough time with it this weekend to see if autotune was doing its job at higher RPM's, I just didn't feel comfortable with it because of the issues seen at idle. Add to it trying to hold/watch the laptop while bouncing about in the sand up/down transitions over some washboards etc. Last thing I want to do is melt my buddies motor down.


Another thing I would love is a way to log to a histogram that looks like the attached. I use this a lot with HP tuners and an excel spreadsheet I built to quickly adjust VE to achieve desired lambda, basically I am the autotune feature Here is how I do it in HPtuners:

Log:
MAP
RPM
Commanded Lambda
Actual Lambda

Histogram in HPtuners provides a value which the VE needs to be adjusted to achieve my desired lambda based on the WB reading. I use excel to take the existing VE and add/subtract a percentage of what the histogram reports. With in 3-5 passes I can generally have desired lambda nailed.

We are planing on putting it on the dyno in the very near future so having the above histogram would be very useful, I am not sure how fast autotune can correct.

[Matt Cramer]

The VE Analyzer in MegaLogViewer is pretty similar to an even more automated approach of the offline data checking.