I got 48# injectors, don't want to push the 24's anymore, then set the pcm for them (just the injector size setting), but what else needs to be done for 6#? I don't think I need a FMU hooked up, right? Will the pcm fuel it right even at WOT?

Hal

 

You will be fine with those at 6#. If you tune with LT1 edit or TC the PCm will fuel for you.

 

So at WOT it runs in open loop and uses the Open Loop vs AFR vs Coolant vs MAP, right?

Hal

 

Negatory.
WOT uses the % change to AFR tables to finger out fueling. It's really not hard if you're using a wideband like you should be. And u dont want to use an FMU if u can just tune the PCM.

From the Help file in tunercats:

WOT % Change To Fuel/Air Ratio Vs. RPM
This table is the percent change to Fuel/Air Ratio used at or near wide-open throttle (WOT) versus coolant temperature. The values from this table and the WOT % Change To Fuel/Air Ratio Vs. Coolant Temp are summed to arrive at the WOT Air Fuel ratio.

The resulting air / fuel ratio can be calculated as follows:

WOT AFR = 14.7 / (1 + %Change vs Cool/100 + %Change vs RPM/100)

For the selected RPM, suppose the percent change to Fuel/Air Ratio from the RPM table is = - 5.1 and the percent change to Fuel/Air Ratio from the COOLANT table at the selected coolant temperature is = 22.7, then the approximate WOT AFR would be:

14.7 / (1 -0.051+.227) = 12.5:1 AFR

 

Thanks, it's now FINALLY clear to me. So with stock settings at 32c and 4800 rpm the stock afr is a super rich 10.5. It looks like if anything the wideband is usually used to make sure things are OK (calculated amount) or pull fuel out, not usually put fuel in, right?

Hal

 

my stock tables show 10.8... Keep in mind that's only 89 degrees F engine temp. The engine will burn more fuel than necissary in order to reach operating temperature faster, probably for emissions sake.

At a normal operating temperature it's more like 12 and a half, dipping as low as 11.7 in seemingly more detonation prone areas of the rpm range.

The wideband doesn't make any changes, it just lets you monitor and helps set the correct AFR, which is crucial in boosted engines. Several times I've seen AFRs over a point off of what I commanded. It helps immensely for tuning and troubleshooting.
I've found mine extremely useful and well worth the ~$200. (genuine new AEM on Ebay)