AutoVE Commanded Fuel Question

[SOMhaveit]

OK, so I loged the PID's for AutoVE and looking at the data during playback I see that I have times that the commanded value is richer than 14.63. At times it is in the 12's. Is this correct and if it is, when I plot the BEN map with this data, is it skewing my map? In other words, if I show a cell that has an average value of 11.8 AFR and the commanded AFR was actually an average of 12.5, will the percent value in the ben map that is pasted and multiplied account for this or is the percent value merely a comparison of the average cell value to 14.63?

[joecar]

In any BEN map cell, BEN = actual_AFR / commanded_AFR where actual_AFR is the AFR read by the WBO2;

So your BEN (in a particular cell) would be BEN = 11.8 / 12.5 = 0.944

This means 12.5 was commanded, but 11.8 was actually read by the wideband, so it's richer than commanded, and the VE table cell factor to correct this is 0.944.

After doing a couple of Auto VE iterations, the BEN values in various cells will converge on 1.00, indicating that actual_AFR equals commanded_AFR for those cells

The commanded AFR is set by the richer of B3605 and B3618 (when PE is enabled) during open loop, and to stoichiometric (14.63 or 14.68) by the NBO2 feedback trim during closed loop.

[SOMhaveit]

OK, thanks. That answers that question. I guess I'll keep after it & hope it doesn't blow up before the AutoVE is close.

[joecar]

Make sure that:
- B3605 right hand 3 columns are sufficiently rich (AFR 12.5 or EQ 1.17).
- B3618 is sufficiently rich (AFR 12.5 or EQ 1.17).

Set your tunetool fuel units to AFR or EQ and not Lambda.

[esco35m]

Make sure that:
- B3605 right hand 3 columns are sufficiently rich (AFR 12.5 or EQ 1.17).
- B3618 is sufficiently rich (AFR 12.5 or EQ 1.17).

Set your tunetool fuel units to AFR or EQ and not Lambda.

Should b3618 be 12.5 while doing the autove or after you are done with the autove.

[joecar]

During and after...

You don't want to run lean under load, it's very damaging to engine's hard parts.

Altho, after Auto VE, you can tune it slightly leaner if you wish (say 12.8-13.2).

At non-load, it should be fine to run 14.7 or something similar.

[esco35m]

Set up Open Loop, Speed Density
1. Upload the current calibration from your PCM.
Save 3 copies of your tune:
i. Original Tune.tun
ii. SDAutoVE.tun
iii. OrgBackUp.tun
2. Open the SDAutoVE.tun
Hint, to quickly find and display any calibration, enter the calibration ID including the curly braces (i.e. {B0101}) into the Navigator and click the [Search] button.
3. Open calibration {B0101} “Main VE Table”. Select all cells by clicking in the extreme top-left, grey cell. Enter 15 into the Adjust text box and click the [%] button. This will increase all cells’ values by 15%.
Note: The increase of 15% is a precautionary measure to prevent extremely lean conditions that may damage your engine.
4. If you are tuning a 1997 - 2000 operating system, repeat step 3 for the {B0103} “Backup VE Table”.
5. Open calibration {B3313} "DFCO Temp Enable" Set it to 122 °C (252° F)
6. Open calibration {B3618} “PE Modifier Based on RPM” Select all cells by clicking in the extreme top-left, grey cell. If the calibration is displayed as EQ Ratio then enter 1.0 into the Adjust text box and click the [#] button to set all values to 1.0 EQ Ratio. If the calibration is displayed as AFR then enter 14.63 into the Adjust text box and click the [#] button to set all values to 14.63 AFR.
support@efilive.com - 5 - www.efilive.com
Is this not correct or is there an advantage to put in 12.5 AFR. I am a rookie and still trying to learn more about tuning. Thanks for any help

[joecar]

The advantage of B3618 being all EQ 1.00 is that you avoid any effects of transitioning from B3605 to B3618 and back;

but, keep in mind that B3605 transistions from EQ 1.0 to EQ 1.17 in one cell's distance.

Either way works.

[5.7ute]

The Auto VE tutorial has been developed from the older method of using trims & still has some of the older methodologies in there. Dial in your PE mode as you would want it on the street & you will be fine.

[esco35m]

The advantage of B3618 being all EQ 1.00 is that you avoid any effects of transitioning from B3605 to B3618 and back;

but, keep in mind that B3605 transistions from EQ 1.0 to EQ 1.17 in one cell's distance.

Either way works.

Joe thank you for clearing it up for me. Like I said im just a noob trying to learn from you guys.