under what conditions does VE table effect AFR? $DA2

Discuss General Motors (GMC, Chevy, Pontiac, Hummer, Cadillac, etc) tuning topics here. Request definitions, discuss parameters, etc.

Moderators: robertisaar, dex

Post Reply
dizwiz24
Posts: 54
Joined: Mon Jun 29, 2009 6:15 pm

under what conditions does VE table effect AFR? $DA2

Post by dizwiz24 » Fri Aug 17, 2012 5:44 am

I was in the middle of a discussion, on another website, about when exactly VE table values affect fueling on a $DA2 speed density tune for 93 lt1 vette.

Some people stated VE table values only affect fueling under open loop operation.

Open loop would also include power enrichment operation as well (correct me if Im wrong by assuming that).....

However, I believe this to be false. I believe that VE table values also influence fueling (perhaps to a lesser degree, but still influence) under closed loop operation also.

It also is the starting point for BLM calculations (ie. if your VE table is off, your going to have more correction and be further away from 128)

The other person I was discussing this with states that in closed loop, the only input affecting fueling is the O2 sensors.

Who is right?

robertisaar
Author of Defs
Posts: 962
Joined: Sat Feb 21, 2009 3:18 pm
Location: Camden, MI

Post by robertisaar » Fri Aug 17, 2012 5:59 pm

the VE table is in use at ALL times except for maybe cranking, depending on the mask.

it's the primary airflow calculation, without it, there would be no basis upon which all other BPW calculations are based. if the ECM knows cylinder size and injector flowrate, but no idea of the mass of air in the cylinder, it can't accurately know how much fuel to inject.

with masks that run MAF only or MAF and VE, this is a different situation.

User avatar
EagleMark
Posts: 424
Joined: Mon Mar 22, 2010 11:11 am

Post by EagleMark » Wed Aug 22, 2012 12:01 pm

Yup! Everything is calculation off main VE table including PE, AE, etc.

Tuning VE table correctly first usually fixes all other issues or at least give correct starting point for other calculations (adders/subtractors).
1990 Chevy Suburban
1994 Buick RoadMaSSter Estate Wagon LT1.
1972 IH 1210 Isky Cammed Balenced 345 TBI

GearHead-EFI.com EFI Conversions and Chip Tuners!

Post Reply