Commanded AFR vs Table B3647

[DrX]

I have been working on the AutoVE tuning but commanded AFR is always a little higher than what I have entered in B3647. 14.7 yields 14.79, 14.64 yields 14.73, etc. All values in A0008 and A0014 are still set to 1.0

Are there any other multipliers/ adders that are active when at full operating temp?

V3-7.71, cal 04073003

Edit: corrected typo- changed 15.6 to 14.79

[kbracing96]

Are you doing your Autove tuning with 14.63 in the table, or 14.7? It should be 14.7, or you won't get an accurate reading to change you VE table. When table B3647 is set you 14.63, it is using STFT to adjust the mixture to get stoich and you will get scewed numbers in the log. 14.7 will not use STFT and should provide much more accurate results.

[DrX]

Are you doing your Autove tuning with 14.63 in the table, or 14.7? It should be 14.7, or you won't get an accurate reading to change you VE table. When table B3647 is set you 14.63, it is using STFT to adjust the mixture to get stoich and you will get scewed numbers in the log. 14.7 will not use STFT and should provide much more accurate results.

If I set it to 14.7 it calls for 14.79(edited my first post). Right now it is set to 14.64 to avoid going into closed loop. That causes 14.73 to be commanded.

[ZL1Killa]

so wait a minute..your saying that in order to properly do the auto ve tune with a wideband and efi live that you must change the table for AFR to 14.7 instead of 14.63?? and then follow the rest of the instructions

I have a 01 trans am ws6 6spd...so I guess i need to go back now and start from scratch and re-log all of my ve values with my wideband and efi live with the table set to 14.7??

[Tordne]

Couple of things real quick:

The numbers that you enter into tables sometimes get affected by the way the PCM interprets and has to work with these numbers. The commanded AFR is a good example or this. I also have my commanded AFR set at 14.7 right now, but when logging the AFR commanded as actually 14.73.

Answer to the second question... The reason for commanding an AFR 14.7 relates only to V3 Custom OS's. This is simply because a commanded AFR of 14.63 causes the V3 OS to operate in what is called "Semi Open Loop", which uses the O2's to trim (which you don't want when tuning your VE). When you are finished you should return to a 14.63 AFR (assuming that is what you want to run).

Cheers,

[Blacky]

The 14.7 v's 14.63 issue is directly related to the type of PCM and the Stoich calibration.
Early PCMs had a calibratable (is that a word?) stoich value, check {B3601} Engine Calibrations->Fuel->Mixture->Parameters. If you have that calibration then that is what the EFILive expects you to use for stoich.
If {B3601} does not exist (i.e. in later model PCMs) the PCM uses a fixed value of 14.63 and that is what EFILive expects you to use for stoich.

Regards
Paul

[Tordne]

The 14.7 v's 14.63 issue is directly related to the type of PCM and the Stoich calibration.
Early PCMs had a calibratable (is that a word?) stoich value, check {B3601} Engine Calibrations->Fuel->Mixture->Parameters. If you have that calibration then that is what the EFILive expects you to use for stoich.
If {B3601} does not exist (i.e. in later model PCMs) the PCM uses a fixed value of 14.63 and that is what EFILive expects you to use for stoich.

Interesting! I thought it was quite strange that some OS's I had looked at didn't have that {B3601} calibration. But, that explains it.

Cheers,

[ZL1Killa]

so for my 01 trans am I can leave the value at 14.63 and be fine doing my VE table or do i need to change it to 14.7 and then log and see??

[Tordne]

so for my 01 trans am I can leave the value at 14.63 and be fine doing my VE table or do i need to change it to 14.7 and then log and see??

Only if you are running a V3 Custom OS and your {B3601} is set to 14.63, or your OS doesn't have the {B3601} calibration (in which case 14.63 is assumed).

In a normal/standard OS you would normally disable the Long Term and Short Term Fuel Trims when doing your tuning.

Cheers,

[ZL1Killa]

gotcha. I have the stock OS, haven't gone custom yet. I did also remember to disable the fuel trims

[DrX]

Now I have entered 14.63 for a large part of B4367. The scan tool shows commanded AFR at 14.68. How will this affect semi open loop functionality?