Beater79TA

I'm trying to optimize a tune that was done by a local shop (now out of business). One thing I've noticed when comparing their tune to the factory tune, is they changed the Mass Air Flow tables which relate voltage to grams/sec of airflow. Is this something that should have been done? Is it even possible to do this properly without a flowbench to test the MAF sensor on? This tune was done with the $32B XDF in TunerProRT.

I understand the need to change the Mass Air Flow vs RPM table to adjust the RPM for each gm/sec reading but shouldn't the relationship between voltage and gm/sec be left alone if the stock sensor is still in use?

hellz_wings

iTrader: (2)

That depends on the mods in your engine. Those tables control how much fuel you give your engine.. You add g/sec of air at any given voltage that means you're telling your engine that there's more air coming in so then the injectors fire more fuel, or lower g/sec to shoot less fuel. The idea is to adjust those numbers until your BLM's hit 128 to have good driveability as this is in the middle of rich and lean.

WOT is another story, you need a WBO2 to really get the most out of WOT.. You can sorta do this with a NBO2 sensor by checking the mv during a WOT run. To be at 12:1 it's about 900mv, but it's not the best way to tune, but should do until you get a WBO2 and access to a dyno to test and tune.

Beater79TA

Reading this thread

https://www.thirdgen.org/forums/diy-...b-tunning.html

It looks like I am correct in thinking the volts for a gm/sec reading should not be changed unless the maf is modified or somehow tested to prove voltage at a given gm/sec.

The changes should all happen in the Max Airflow Vs. RPM table to show the rpm where the engine maxes the gm/sec reading.

88gunmetalgta

iTrader: (1)

$32 and $32b have a base pulsewidth table that can be modified. $6e and other MAF masks don't, so tuning via the MAF tables is the only way to adjust fueling.

There's nothing wrong with what the shop did, but it probably would have been easier to just use the BPW table.

WOT tuning is accomplished through the PE tables, Max airflow vs RPM basically does nothing. Unless your engine has lots of extra cubes and then you'll have to raise the values so you don't hit the gms/sec ceiling there.

Beater79TA

The engine is a miniram'd 383 so I fully expect to run out of gm/sec on the MAF well before the engine runs out of usable RPM.

The changes also were very small and randomly spaced in the tables. Some lines still matched a stock bin and others were sometimes higher and sometimes lower. The BPW table is unchanged from stock but the timing table is definitely modified. Looks like it's time to do some datalogging if it stops raining and start the process of dialing it in.

hellz_wings

iTrader: (2)

I was referring to the 6E bin, using MAF Tables 1,2,3....etc.... I'm not sure about 32B.

Although I do know that Max airflow vs RPM table needs to be increased if you are hitting the g/sec ceiling as a result of increased cubes. You should be able to determine this with a datalog and it will tell you where you're at when you're flooring it at a particular RPM.