I have modified my MAF by removing the screens and cooling fins. I have read in searches and can understand how these changes could affect the MAF's reported readings. It seems to me that removing the screens wouldn't have as as much affect as the removing the cooling fins, but maybe that's beside the point. I am running a bit lean across the board with BLM's in the 135-140 range. I was planning to change the injector constant to bring the BLM's in line but wonder if the MAF tables should be also considered.

The questions I have regarding the MAF mods are;

1) Should I change the MAF tables or Scalars?
2) Which one (or both)?
3) How do they interact with one another?
4) Could the altered MAF be causing the high (lean) BLM's?

Tried to keep this to the point and any input would be greatly appreciated.

 

The MAF tables themselves are what you alter. The scalar is used to keep the values in the tables < 256 so the values dont go out of range. You'll only need to change the scalars if values get too small or max out in the table. Altering the MAF causes more airflow to bypass the wires, which will cause the motor to lean out.

 

OK makes sense. So I would go to the MAF table(s) and raise all the
gm/sec @ volts values by some percentage (say 10 %) then relog and see what happens. That would tell the computer that the air flow is higher for a given volt reading at the MAF and therefore enrichen the mixture to compensate. Right?

Does anyone know what percentage change would be a good starting point for a MAF with these mods?
Do I need to change all the tables or just the first three, for example?

 

If you change the MAF tables, you must also change the scalars.

Actually, if you set up your MAF Tables Conversion to be Y/256*X, and have Y be "Other XDF Item Output" and "Choose Reference Item" to be "Maf Table # (each table match to each scalar) Scalar" it will automatically update each table's equation if you change the scalar.

Then, you can FIRST increase the scalars by 10% (mult each by 1.1 in decimal, don't just increase by 10) (except Table 6, it's 255 already), and THEN go into each MAF table and REDUCE the lower flow portions to match up to the PREVIOUS (Lower) MAF TABLE'S HIGHEST VALUE. Blend it properly keeping the curve in there like stock. In table 6, it will hit 255 sooner, though.

Other method (and actually very valid, in my opinion), DECREASE INJECTOR FLOWRATE CONSTANTS by 10%. Then, no MAF recal necessary, and your MAF will now work to 10% higher horsepower before it gets limited by the false 255 g/sec limit. Your load (LV8 calculation) will not be 100% correct, though, but you can fix that too by adjusting the Load scalar (at 5B0). It's only useful for spark and open loop offsets, and it's not a large change.

 

For Q#1, its pretty simple, you changed the MAF, so you should change the MAF tables. In this case (and for my MEGA MAF) I let the BLMs guide me on how much to alter the MAF tables. If I had BLMs close to 128 before the MAF change, then I adjust the MAF tables to get the BLMs back to where they were before the change. I have used the same strategy on my OBD2 '99 Camaro LS1 car.

For my MEGA MAF that I built, I needed a huge change to the MAF tables, that I had to use a different tuner ( I had been using CATS tuner, now TunerPro RT) which allowed me to alter the MAF scalar for each table, which in turn, changed each value upward in the 6 MAF tables.

 

Thanks for everyone's input.

RednGold; Your "other method" is what I have been considering. I understand your method of changing the MAF tables and scalars and believe it will come in later. I want to keep it as simple as possible for now. Please note that I am using TunerPro RT and am limiting my adjustments to what the program will allow me to do. (I'm not working with the source code) Is the following statement correct?

"Reducing the injector constant will compensate for the modified MAF, richen the mixture across the board and bring the BLM's down. It may alter the LV8 slightly but not signifigantly affect overall tune. Adjusting the MAF tables and scalars may be the correct way to do it, but cheating the information (by injector constant) will correct 90% of my problem. I can later go back and tweek the MAF tables/scalars for the last 10%."

 

I was under the impression the scalars weren't to be touched due to a loss in overall resolution?

I thought you could move the various values up/down in each MAF table to achieve a 128 blm. Is this not true?

Thanks.

 

I agree with the advice from RednGold. In your case the change to the MAF sensor is not that great so I would think either method will work. Probably the easiest is the second method by changing the injector constant and you may have to do some minor tweeks to the MAF tables at and near idle.

I have been working on a setup where the MAF sensor was mounted into a 4" tube. I tried to change only the MAF tables and scalars only but end up at the 255 limit about half way through the tables. This is a big loss in resolution. So I have also been trying by the other method. For this setup I currently have the injector constant set at about half of the actual injector flow rate and am tweeking the MAF table to futher fine tune it in. Still working on this, we'll see how it all turns out when we get better weather.