How do you control mid-range air/fuel ratio?
#1
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How do you control mid-range air/fuel ratio?
My car will bog down when i start to accelerate heavy in third gear. The wideband shows it running fairly lean say 14:1, as I go deeper into the throttle and it goes into PE mode the A/F will jump to 12:1 and the power snaps up. What do you adjust to trim the fuel curve outside of the PE mode? If I could fatten it up a little at the time of the bog it would fix it. Thanks.
#2
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You would want to lower the PE mode delay RPM
and the TPS required to get into PE. Then adjust
your PE vs RPM and your open-loop fuel/air tables
to get what you want, where you want.
Tip-in bog can likely be fixed by fattening up the
low to mid RPM portion of the VE table (esp. if the
bog is due to KR).
You might be happier with a higher-stall converter
than that 2600. It's a bit tight and may be keeping
you out of the powerband especially if you have stock
part throttle shiftpoint settings.
and the TPS required to get into PE. Then adjust
your PE vs RPM and your open-loop fuel/air tables
to get what you want, where you want.
Tip-in bog can likely be fixed by fattening up the
low to mid RPM portion of the VE table (esp. if the
bog is due to KR).
You might be happier with a higher-stall converter
than that 2600. It's a bit tight and may be keeping
you out of the powerband especially if you have stock
part throttle shiftpoint settings.
#3
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Thread Starter
I read that the VE table is for open loop only. Is this true? I don't have any KR and the stall is not the issue here. Once it gets the extra fuel from the PE mode it pulls fine. The question is how do you modify the air/fuel ratio when it is in closed loop? I guess I could lower the PE engagement more (its pretty low now) but I was hoping I could trim the closed loop A/F.
#4
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Can't stay closed loop away from 14.7:1 because the
narrowband O2s are not going to give you meaningful
feedback; saturated low or high and the loop is broken.
VE works down low and during unsteady MAP. Like tip-in.
Below 4000RPM is is involved in the airflow calculation to
varying degree.
You can adjust the target AFR, and the O2 voltages that
represent that AFR at various airflows, but that is messy
and not what you want.
PE is one way to get into open loop and the only one that
is really handy. Just use it, and tailor the enrichment to
get what you need.
narrowband O2s are not going to give you meaningful
feedback; saturated low or high and the loop is broken.
VE works down low and during unsteady MAP. Like tip-in.
Below 4000RPM is is involved in the airflow calculation to
varying degree.
You can adjust the target AFR, and the O2 voltages that
represent that AFR at various airflows, but that is messy
and not what you want.
PE is one way to get into open loop and the only one that
is really handy. Just use it, and tailor the enrichment to
get what you need.