mnorton

Would it be reasonable to assume that with a modified MAF Sensor that has had the Rear Screen Only removed, that the Airflow Gram values-vs- Throttle Position Sensor Voltage in the stock MAF Tables are all now too low?

And based on that idea, if I were to increase them all (for each of the 6 MAF tables) by say 8% to compensate for the additional airflow, would that make sense, or is my reasoning way too simple?

I'm thinking that the non-linear airflow and sensing characteristics of the MAF sensor is already factored into the stock MAF Tables baseline numbers, so an 8% increase on each individual Table entry would be fine.

I have an LB9 with 22# SVO injectors (injector constant currently set to 22.3), AFPR set to 49 PSI, K&N Airfilters, Gutted Stock Airbox, World S/R 305 Heads (1.94 intake Valves), Crane 2032 Cam, 2055 Headers, 3" Catback so I suspect that the system pumps air/fuel pretty well now.

It shows that it's Lean when I look at the BLM's (140), while the idle smells rich. Raising the Gram values in MAF Table One at idle (around the .55 volts area) by 8-10% brings the idle BLM's down to 128.

I have not been able to Datalog yet.

DSmith

Personally I don't think removing the screens will affect the calibration of the MAF sensor. True it will help flow more air but the area where the air is measured is not changed.

Thats just my
Dewayne

mnorton

I think that the real issue here is; Are the TPS-vs-Airflow values in the stock MAF Tables still correct on an engine that flows air more easily than stock?

I suppose that just removing the Air Filters would do as much to improve the airflow as removing one of the MAF Sensor Screens.

antman89iroc

Ok here's my opinion and experiance.

Theory

First of all I agree that removing the screens should not change the maf calibration since the material removed (screens) is not in line with the wire which is "sensing" the air flow. IOW the air is not "bypassing" the wire, hense the reading should be the same. The expamle sited that installing higher flowing air filters increases the air flow to the engine but the "mass" of air reported by the meter should remain correct. This doesn't mean the "tune" won't be off, just that the maf is correctly reoprting.

Second, removing the fins should change the calibration since the fins are directly in line with the wire. IOW more air is going through the meter but the "mass" of air going through the space where the fins used to be is not figured into the maf meter's calibration. The reoprted air flow through the meter is lower than what's actually flowing through the meter.

Experiance

My maf has the screens and fins removed. I adjusted my scalers by 10% (* 1.1) and tweeked some of the maf tables more than that.

Opinion

It seems to me that the flow throught the meter is not linear, probably due to eddy currents and channeling. I believe this is why the screens are most likely there in the first place. To straighted out the air flow rather than keeping bugs and such off the wire. When I removed the screens the effect was that air swirled and channeled through the meter in such a way as to "sneak" by the wire, therefore the "mass" of air flowing throught the meter was under reported. This is why I believe the scalars/tables have to be tweeked due to removing the screens. However, removing the fins actually allows air to bypass the wire (sensor) and requires changing the scalars/tables.

If I had only removed the screens, I would start with +5% at the scalars. If only the rear screens were removed, I don't think I would change them at all.

curacaoz28

so look I have a stock 305 tpi do u recommend me to remove the screen?

Rebuildman

I think if you do a search on this subject you will find pages of info related to screen removal. This was a big issue years ago when this website first started but the info should still be relevent. I believe back then it was finally decided, or not, it was best to leave the screens in unless it was an all out race, wide open throttle motor.