How to change cruise/light throttle fueling?

[csufdrew]

Background - have had my AGP SCT Flash for over 1 year and just recently noticed my AFRs when in vac cruising on the freeway (13.8-14.0) ALL THE TIME. Even crusing around town my AFRs are like that.

AEM wideband shows 14.7-15.0 at idle and both fuel trims are +/- 5% everywhere.

When I give some more throttle & boost is 5-7psi, the AFRs read 14.7-14.8.

How many different fuel tables are there to determine AFRs at cruise and NON-WOT conditions?

thanks guys

[julius717]

Quote: Originally Posted by csufdrew

Background - have had my AGP SCT Flash for over 1 year and just recently noticed my AFRs when in vac cruising on the freeway (13.8-14.0) ALL THE TIME. Even crusing around town my AFRs are like that.

AEM wideband shows 14.7-15.0 at idle and both fuel trims are +/- 5% everywhere.

When I give some more throttle & boost is 5-7psi, the AFRs read 14.7-14.8.

How many different fuel tables are there to determine AFRs at cruise and NON-WOT conditions?

thanks guys

mine does the same thing. with the stage 2 tune im ALWAYS 14.0-13.8 at crusing i just flashed back to stock 05 map adjsted for 3bar and not my cruising a/fs are about 14.3-14.4.....??? im not really worried sicne my real tune will be done in a week or so. guess ill post back info then

[apexcrazy]

If you have the pro racer package , open the advantage software & under the fuel section open the scalars , there are three values that deal with this . stoic fuel ratio , even cylinder stoic , odd cylinder stoic . some base codes different values input here . See SCT wiki for proper explanation , but suffice to say by changing this value you can slightly influence afr target . I think mine are currently set at 0.0689 , which seems to get me 14.6-14.7 afr at idle .

[Nick Chestnut]

You cannot change closed loop AFR. The oxygen sensor in the SRT-4 is a narrowband sensor with a 1.0 lambda center point calibration. The PCM simply adjusts fuel based on feedback from the O2 sensor. The PCM only knows if the air/fuel mixture is richer or leaner than a lambda of 1.0; it does not at any point in time "know" the actual air to fuel ratio.

Now there are sections in the calibration that allow you to theoretically change stoichiometric F/A. Some testing indicates that changing this value has a minimal impact on closed loop AFR. The keyword here is minimal though... If these reports are correct then changing this value simply allows you effectively shift the PCM's O2 sensor switch voltage by some small amount.

Drastic variations in AFR during closed loop conditions generally point to a problem with the O2 sensor.