Trouble tuning VE

[bmorrow8]

Hey guys. I have been chasing my tail the last several months nailing down the idle. So I decided to revisit my VE. I decided to take an hour drive and try to hit as much cells as possible. I have some filters from ERM tuning that I use to filter out bad data. engine temp, throttle snap, PE activation noise, commanded EQ, fuel trim cell and cell count to 100. After finding my EQ error and plotting against VE table paramater, I get a VE that looks like this.(see attachment) over and over. No matter the filter, I get a dip in VE at 2400rpm. What would cause a consistent dip in fueling at a certain rpm across the map range? I have filters to exclude shift changes ( throttle would open or close too quickly so my filter would not allow that data, filter = less than or more than 3% change of throttle position over a 300ms time frame)

set up:
1986 c10
ls1
prc heads - 10.5:1 CR
btr stage 4 car cam (with supporting mods)
long tube headers
4inch CAI
ls3 MAF/IAT
holley 102mm TB
Stock replacement IAC
MSD atomic air force intake
stock ls2 injectors and rail
return style fuel system
t56

[charcoal03silvy]

Not the worst looking VE table I've ever seen by any means. Are there any ill-effects of it being this way? What makes you think "its a problem".

If the vehicle runs well, the target AFR is reaching commanded, etc, then do a slight bit of smoothing and move on to the MAF.

The only thing that does look a little strange is the really high VE numbers at WOT. That typically would indicate incorrect injector data, engine displacement value, or possibly low fuel pressure. Double check those things for sure.

In summary, if AFR is in line with target, move on the the MAF, then revisit idle and have fun driving it.

[kingtal0n]

Could be injector data, or system voltage. Or just the way you are collecting data. I get something similar sometimes on all kinds of cars.
For example at 2400rpm maybe your alternator kicks up volts from 13.8 to 14.3v by overcoming the current draw of several large fans or pumps (or just by being a small alternator). The increase in voltage helps injectors open faster (snappier response) and you get more fuel that way. The injector data should compensate because it goes delay vs. voltage but it may not be right.

Won't hurt anything as long as you tune around it like was done.



You may want to smooth the VE map though. Notice the graph itself looks 'jagged'. Try to get it to flow over the surface of a smooth pebble like water.