Fuel multipliers and tuning VE

[CDeeZ]

OK good to know.


I was just thinking that the VE would be different at 3200 RPM than it would be at say 4000 RPM, I'd assume it would be less at the higher RPM, so I was thinking that if you tune for one then the other will be off? If the ECM uses the last cell in VE1 that it was in, whenever the RPMs exceed 3200, and if VEs typically decrease with RPM, how do you tune for less VE at the higher RPM, W/O screwing up the VE values for running along AT 3200 RPM?


ASDW9544 is the bin I started with. And it has the value 39.06 from 400-3200 RPM in VE2

[EagleMark]

VE does not decrease with RPM. Look at any VE table and it always goes up with RPM and load, never down. Except in a case where it is a limiter like VE2.

I see what you mean about the same till 3200 RPM, but after that they all drop as a limiter, not because of need. Before I did mine this way it would fall flat on it's face and shift because of the limiter, now I have to lift the pedal to let Auto trans shift or it would keep reving. I changed PE to 11.5 to 1 AFR to get it to read 12.8 to 1 on Wide Band.

[CDeeZ]

I stand corrected.

So any time you're dealing with a 7747 you just zero out the entire VE2 and only worry about VE1 that only goes up to 3200 RPM??

[EagleMark]

You can ask several differant ways several more times and the answer will always be the same.

It's worked for Tuners better then I and has worked well for me, from stock to slightly modified to a 440 Mopar Six Pack Engine converted to TBI that revved to 5200 RPM...

It's such an easy, popular and available ECM that I think I'll give a shot a reworking the fuel table to 6400 or? as Robert suggested, but ain't happening till winter. It's been so long since I have seen sunshine and it's almost here!

[CDeeZ]

Sorry for beating this question to death, just trying to wrap my head around it.


That would be awesome if you whipped up a full size fuel table for the 747, I'd offer my help but not sure I have the expertise to tackle such a task, but nevertheless.

[EagleMark]

I had a hard time with it myself the first time. All is well.

Wish we could get Robert to buy an old 7747 truck so he had something OLD to play with, he'd have this whipped in no time...

[CDeeZ]

You can add 2 to 4 degrees to this table outside idle spark on stock motor safely for all weather year round.

What do you mean by 'outside idle spark'? I'm going to try adding a few degrees to the whole table as you mentioned and see what kind of effect that gives me.... Is there a range of cells I should stay away from when adding these few degrees of spark or can I hit the whole SA table with 2-4 additional degrees???