LSJ MAF Calibration

[Pyros777]

Time for the noob question of the day.

How do you know when your MAF is scaled correctly?

Is it when your LTFT/STFTs are at 0 give or take a bit?

What if this results in MAF lb/hr readings that *could* be right, but seem a little high. (36 lb/min peak on a 2.99 pulley, 3 inch intake, 17.4psi, and a mostly zeroed out LTFT). Before tweaking the MAF tables on my stage 2 tune I was seeing a peak of about 32 lb/min.

My method of MAF calibration is a little wacky, but seems to work. I just wonder whether I'm skewing my MAF readings just to appease my LTFT/STFTs. I just want to know that I'm calibrating my MAF correctly, and not fudging numbers.

This is my method, for better or worse:

1.) Copy/Paste the MAF values from my tune file to the "C" column of an excel spreadsheet, with labels. This will extend down to the "AK" column for the LSJ.
2.) Open an HPL log, convert to CSV, and copy the entire LTFT and MAF Hz columns side by side to the "A" and "B" columns of the spreadsheet.
4.) Now comes the wacky part...

The spreadsheet needs to read and average all LTFT hits within a given MAF Hz range within 300 Hz of each MAF table. For instance, I have the formula average all LTFT hits that correspond to any MAF readings between 2850--3150, and that gives me the average for the 3000 hz table.

Once I have my LTFT averages for each MAF table, I convert to decimal since LTFTs are percentages, then multiply my original MAF table value by that number to find out how much I need to add or subtract from the original value.

SO, if my original table value is 1.271, and the average LTFT for the 3000 Hz table is 2.028, I need to add 2.028% to the original, giving me 1.297.

I've run my logs through this "filter" several times, and every time I get closer and closer to zero. Its really exciting to watch it happen, but I'm a bit in the dark without confirmation that I'm doing things right.

If my method is confirmed to work, and anyone is interested, I'll clean up my excel spreadsheet and post it for all LSJ people to use.

[omega_5]

Excel is not needed (unless your doing really complex stuff).

First, read through the manual for the VCM Scanner... it will make life a whole lot easier. Especially the histograms part.
Next, read through 04Redline's tuning guide on RLF.

On a final note... I'm assuming you know that you can only use fuel trims to tune the low end of the table.... right?
You will need a wideband to tune with any accuracy at the top end / WOT.

[Pyros777]

Thanks for the responses!

Yeah it may seem complicated when explained, but its really not when you get down to it.

I chose excel rather than using a histo because I wanted to grab the average of a range using the AVERAGEIFS function, and I'm pretty sure theres nothing like that in HPT.

I realize I may be doing this differently than most, but the results seem to be the same.

@omega: I had a feeling that this would only be accurate to a point. I should have a wideband sometime next week.

[omega_5]

I chose excel rather than using a histo because I wanted to grab the average of a range using the AVERAGEIFS function, and I'm pretty sure theres nothing like that in HPT.

You can pre-filter your data in a range, then run an average. It will essentially accomplish the same thing.

In the end it's all about saving time and resources. A properly set up histogram, while very time consuming, will save you boat loads of time when in the car.