EDIT IFR TABLE OR NOT??

[GTO155]

My question is this. What tables need to be edited to adjust A/F. I want to leave the MAF on, so SD tuning is out of the question. Some people recommend first to scale the IFR tables then PE tables and some say not to touch the IFR tables with stock injectors. If i leave the IFR tables as is and only edit the PE tables will it work?

Which way is correct??

GTO 155

[jimmyblue]

The stock IFR table seems to match the stock fuel system
pretty well. So why mess with a working model? Only if
there's something about the fuel path that has changed.
Fuel filters want changing though.

MAF table for a MAF that's non stock. VE table for things that
have changed the breathing of the motor. PE and open loop
fuel air tables for power enrichment.

[GTO155]

thanks jimmy blue, that makes more sense know.

some people seem to complain that they experience no change when they paly around with the PE table so they start scaling the IFR table

[jimmyblue]

About the only way not to see a change from PE,
is if you have another "enrichment source" that is
commanding a higher value. Open Loop Fuel Air
is one that's always "in the race" (always an
enabled option when PE mode; PE is always open
loop but open loop is not always PE). This table
wants to be kept synced up with any PE changes
you make. Though stock I saw this table reasonable
and PE table fat. Also COT (Cat OverTemp protection)
when active will override with a much higher fuel
air multiplier.

[sleeperstyle]

so- with positive ltft's editing the pe table won't matter?

[jimmyblue]

They will combine to produce more fuel than commanded -
if the MAF were suddenly right, at the upper RPM. If the
+LTFTs result from a MAF error in closed loop that has been
nulled, then carrying that trim forward into WOT is probably
helping keep actual AFR closer to commanded. But, if the
+LTFT results from another unrelated error source (like
especially a bent speed-density tune, which above 4000RPM
is out of the picture, that enrichment is put onto the MAF
tune that doesn't need it and you get excessive enrichment.

You can tune PE by effect to get the right AFR but if the
+LTFTs are there, thay are also there variably and this makes
for a lack of repeatability in fueling; sloppy at best.

[MNR-0]

IFR or MAF scaling - its all the same. You need more fuel because you are running lean. In the old days there was no such thing as scalable airflow and it was all about adjusting the mixture via the carby. Equivalent today is rescaling the IFR table. Worked then, works now. No worries.