PE Questions ?????

[The devil]

I know that this is a repeated issue but it is driving me crazy.

As I understand from the forum that PE is a multiplier. We set the PE table according to the AFR we want at WOT, example if we want WOT AFR to be 13.0 we divide 14.7/13.0= 1.13 which is the PE value for the whole table (we want AFR to 13 in all rpm’s) BUT:
1. In real life they will differ (different rpm’s have different values) WHY?
2. If I change the injector size, these values will also be different, so the equation that we use earlier will not work cuz 1.13 from 30 lb injectors is not the same as 1.13 from 42 lb injectors? (So there must be other factors that affect our PE table WHAT ARE THEY)?
3. If we want to nail the PE table by calculation (CAN WE DO THAT)? BTW I’ve done my PE table by creating a histogram that gives me the % error to the AFR I want ).

One last thing:
I know that numbers in VE table are how long the injectors are opining (not the fuel amount) to make the mixture 14.7:1 at X RPM vs. Y MAP. There for, can we use these VE numbers some how in equation to make the mixture 13:1 to calculate the PE table cuz we still in Y of MAP?

[Bill@HPTuners]

1. In real life they will differ (different rpm’s have different values) WHY?

This is where tuning comes into play, if your other tables aren't 100% accurate there will be a difference.

2. If I change the injector size, these values will also be different, so the equation that we use earlier will not work cuz 1.13 from 30 lb injectors is not the same as 1.13 from 42 lb injectors? (So there must be other factors that affect our PE table WHAT ARE THEY)?

The injector size tables need to be altered as well.

3. If we want to nail the PE table by calculation (CAN WE DO THAT)?

Yes

One last thing:
I know that numbers in VE table are how long the injectors are opining (not the fuel amount) to make the mixture 14.7:1 at X RPM vs. Y MAP. There for, can we use these VE numbers some how in equation to make the mixture 13:1 to calculate the PE table cuz we still in Y of MAP?

you might want to study what ve is for a much longer time.

VE-volumetric efficiency ie NOTHING to do with injector pulse widths. Tells the pcm how efficiently the engine is flowing AIR at any given point.