i just put in 42's and a calibrated blow through maf in my 95 with a turbo. no tune on the factory computer my air fuel is reading 11.1-11.3. is this normal or should it be in the area of 14.5-14.7?
air/fuel ratio with 42's
- Thread starter 95Stang50
- Start date
Ok let me clear this up some. I know I need to get a tune. That's not my question or concern. All I want to know is, is it normal to have an air/fuel ratio of low 11's with 42's and a calibrated maf?
Once you get into the arena of a turbo and 42lb injectors, nothing is normal or un normal. Every car is going to react differently because there are too many variables.
Kurt
Kurt
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.
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
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
BlackVert
15 Year Member
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.
blksn955.o
Founding Member
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.
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.
BlackVert
15 Year Member
blksn955.o
Founding Member
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