AutoVE Best Power Advise

[Rusty]

What is the best way to get the PCM to produce AFR around 13 after I complete the AutoVE?

Option One: I can either change the calibration {B3605} “Commanded Fuel When in Open Loop” to desired best power AFR numbers for all MAP values greater than 60 kPA.

Option Two: Leave B3605 at 14.63 and use {B3618} “PE Modifier Based on RPM”. I am guessing values of .85 in table 3618 will lower then AFR when in PE mode to around 13 AFR.

Which way is best?

[5.7ute]

Since you are using a factory OS where fuel is temp over map in B3605 I would be using B3618 as it will give RPM based fuelling control while in PE. I would still enrichen B3605 however as a safeguard from 70 kpa up. Since the richer of B3605 or B3618 (plus modifiers) is your commanded afr you will need to ensure B3605 is set slightly leaner than the leanest point in B3618 to keep this table in control throughout PE.

[bobbycollier]

Actually I like the custom OS 02020005 which I use with my 1999 PCM in a C5 Vette. It has a commanded fuel table based on MAP and RPM. You can set it up so you have different commanded fuel settings in different scenarios like idle, cruise, increasing load, etc. It allows you great control and smooth transitions between load levels. You can accompany that table with some richer RPM-based PE settings for extra fuel & safety when you stomp on it.

[Rusty]

Since the richer of B3605 or B3618 (plus modifiers) is your commanded afr you will need to ensure B3605 is set slightly leaner than the leanest point in B3618 to keep this table in control throughout PE.

So the PCM will use which ever value is richer. I was concerned that it is a blend.

AFR=14.68
13.21=.9 X 14.68

Does a value of .9 in B3618 = a value of 13.21 in table B3605 (excluding other modifiers)?

[5.7ute]

If viewing in AFR just enter 13.21 in B3618. This table represents the AFR you wish to command and is not a modifier as such.

[joecar]

+1 what 5.7ute said.

Some notes:

B3601 is your stoich AFR (which represents EQ 1.000 for you)... usually B3601 is either of (depending on original tune file): 14.68 or 14.63.

EQ is related to AFR as: EQ = B3601/AFR
AFR is related to EQ as: AFR = B3601/EQ

You can view B3605, B3618 in AFR units or EQ units (Edit->Properties->Display->Commanded Fuel Values);
be careful you do not have Lambda units selected, you/I will get confused (Lambda = 1/EQ).

B3618 is not a modifier, it is either the AFR (AFR units) or EQ (EQ units) based on B3601 (as said above).

When PE enables, PCM selects richer of B3618 or B3605 (or B3647 if using COS).

If B3618 is EQ 0.9... the AFR this represents is B3601/0.9 = 14.68 / 0.9 = 16.21.
If B3618 is Lambda 0.9... the AFR this represents is B3601*0.9 = 14.68 * 0.9 = 13.21.
So be careful with fuel ratio units.

The only way you can have values less than 1.0 in B3618 is if you have Lambda units selected.

If you're not comfortable with EQ units, then select AFR... but be careful with modifiers, they modify the EQ value directly (the math is direct/easier).

[Rusty]

Thanks for the help. I believe we are all on the same page!

My last step is to calibrate the MAF. I do not have a wideband to log flow. I only have the wideband O2. Is there any autoMAF procedure posted? Can I compare GM.DYNAIR to SAE.MAF and adjust the MAF calibration to match. I know there is a time offset from GM.DYNAIR to SAE.MAF but I see the relationship. I do not know / trust the current B5001 table. It does not match any values from stock files and the actual sensor has been moved further away from the throttle body than stock.

[joecar]

To calibrate MAF:

1. calculate IFR table B4001 using spreadsheet.
2. do AutoVE (MAF is disabled, CL is disabled).
3. enable MAF and set B0120 to zero.
4. in the scantool locate the B5001 map for your wideband (or create one).
5. log data, apply filter to map, paste/multiply map into B5001; repeat as required.

The procedure is just like AutoVE, except that you are now using the MAF for airmass, and you are appying the BEN correction to the MAF table...

Setting B0120 to zero makes the PCM use the MAF exclusively, from what I understand.

Steps 1 and 2 may be optional depending on what you want to achieve and who you talk with... ;)

If you did step 2 (AutoVE), you could use DYNAIR to create an inititial MAF table... I believe DYNAIR is computed independently of MAF.

[joecar]

If you then set B0120 back to stock (4000 rpm), then then PCM uses:
- above 4000 rpm: MAF exclusively,
- below 4000 rpm: MAF during steady state, VE during transient conditions.

[Rusty]

Great. Seems simple. You guys have been really helpful.