gtodoug

iTrader: (1)

I know this is going to sound stupid but I have to ask. I know the purpose of tuning your VE table is to improve all around driveability and more importantly to get fuel trims in line so that we aren't over compensating for lean conditions when entering PE mode. However, I 'm not understanding something. If I am in SD mode and go WOT you enter PE mode and it's referencing whatever value is on the PE vs RPM table which should be a divisor of stioch comanding a certain AFR. Right now my table is set to 1.350 which is like 10.8-10.9 afr correct? Is this divisor in the PE table only as accurate as my VE table? Or is the point to get it so that we aren't adding fuel and as long as it isn't compensating by adding additional fuel we're ok.

Also what I'm really trying to figure out is if when we tune the VE table and tune up to 5600 rpms or so and just follow the trend up to redline on what we think the VE table should look like are the values we are using in the PE inaccurate for the areas we didn't actually tune LTFT's for?

I also remember people saying they were going to reconnect their maf after tuning up to 4000 rpms or so. If you did do that and got your trims in line and reconnected the maf is the maf determining how much fuel is needed at that point or is it still referencing the VE table in open loop with the maf connected? Would your values you use in your PE table past 4K not really be accurate since you only tuned up to 4k?

I'm confused just listening to myself bable. Please help.

soundengineer

iTrader: (16)

you can tune all the way to redline by making your car not enter PE mde...by setting PE Enable MAP to 640....
then just tune it all the way to redline just like you did for teh rest of the table.

For WOT you really need a wideband...every car is different...
My car is right on with a 1.250.... which math wise should equal 11.76=suck...but wideband says 13.0 across the board
a buddy of mine who bought my old car...with tons of mods....his table says 1.336....and its right on 13.0 with a wideband....


also do all od this in Speed density mode...
then tune your MAF calibration using one of 2 different recalibration excel spreadsheets on here......personally I like my spreadsheet cause you follow the same basic thing you did for LTFT...
http://www.audiohelix.com/hptuners/M...-Worksheet.xls

jimmyblue

iTrader: (11)

Whatever error you have in the airflow measurement,
you will have to compensate for in tuning the PE.

The VE table is ignored above 4000RPM under steady
MAP conditions so the system (if you leave it be) is
pretty tolerant of errors on the speed-density side
for this particular region of operation (WOT steady).
Erring to the rich side on high-end VE is probably the
right way to go, not much of a downside.

The MAF is not a bad instrument up top but it can be
fooled to the tune of several percent (just look at the
differences between the various 85mm MAF tables out
there).

VE table = data, MAF table = data, PE table = command.
You can make good decisions based on bad data but it
takes more careful thinking. Once the airflow metering
is stable (not to say perfect), you just have to tweak in
the PE (and don't neglect the OLFA table) to the present
realities.

gtodoug

iTrader: (1)

The OLFA table. What do I need to do here. I assumed the table is an adder if map/coolant temps aren't inline(anywhere othere than a 1.00 on the table). I searched, but could you elaborate what I might want to be changing here?

gtodoug

iTrader: (1)

Ok, regarding my other question just make sure the trims are neg, but not too neg, and get the VE table as close as possible. On the dyno this friday leave it in SD mode and tune PE table to desired A/F ratio. I'm going to shoot for 12.7:1 AFR. I'll be using a dynojet.