air/fuel ratio with 42's

i would say without a tune, yes.

someone correct if i'm wrong, but the calibrated MAF only gets you close but you need a tune to finish it. your injectors are still staying open as long as the 19#s were, but since you now have larger holes, there is more fuel going in each pulse. so you will be rich. again, getting a tune should clear it up. the only other thing that i can think of would be to back off the fuel pressure, but then you'll be hurting yourself in WOT and higher RPMs.

When running inj's that big
and
A meter that has a matching cal

No telling what you are gonna come up with

You really can't say a certian size inj and certain meter is gonna
produce a certain a/f ratio at idle

WAY TOO MANY things are in play at this condition :Word:

So ... From my point of view ... I don't see how I could give you an
answer that would even be in the ballpark as they say

Grady

ProKiller said:

i would say without a tune, yes.

someone correct if i'm wrong, but the calibrated MAF only gets you close but you need a tune to finish it. your injectors are still staying open as long as the 19#s were, but since you now have larger holes, there is more fuel going in each pulse. so you will be rich. again, getting a tune should clear it up. the only other thing that i can think of would be to back off the fuel pressure, but then you'll be hurting yourself in WOT and higher RPMs.

Click to expand...

this not quite accurate ...

the thing that makes a MAF "calibrated" for injectors is that it is "rigged" to return a voltage that would fool the computer into opening the injectors for the right amount of time.

an example would help (this is just an example, not actual values):

in a stock setup, a MAF reading of 2.6V might mean 50 lbs of air per minute is coming in, and for 19# injectors, the computer would open the injector for 1.7ms.

to calibrate a MAF for 42# injectors, the MAF would have to return a lower voltage for the same amount of air, so that the computer will open the injectors for a shorter amount of time.

19#/42# = .452, so this is the factor that is used

so a MAF calibrated would read 2.6*.452 = 1.176V when 50 lbs of air per minute is coming in.

make sense?

now think about the lowest limit of the air coming in ... idle. the stock MAF voltage is already very low for idle conditions, because that is the bottom of the range. the calibrated MAF's voltage will be .452 of that, or even lower. that may approach the lowest limit for how short the computer can tell an injector to be open, or be at the bottom of the table the computer uses to determine how much air that voltage means is coming in.

Also to note the "cheat" mafs tend to be off or have issues the larger you go from stock.

Honestly, with the options out there either get a LMAF (if your looking at around 400-450wrhp) or an SCT maf. The tune will be miles ahead and with less headache for you and the tuner.

At idle a boosted car should not "see" any boost and normal A/F ratio's apply...IE targeting the 14.9 range. 11's is super rich.

blksn955.o said:

Also to note the "cheat" mafs tend to be off or have issues the larger you go from stock.

Honestly, with the options out there either get a LMAF (if your looking at around 400-450wrhp) or an SCT maf. The tune will be miles ahead and with less headache for you and the tuner.

At idle a boosted car should not "see" any boost and normal A/F ratio's apply...IE targeting the 14.9 range. 11's is super lean.

Click to expand...

i'm sure you mean super rich.