pcmhacking.net

Well I thought I'd try tuning a LS7 card style maf today & had been told you need to adjust quite a bit....

For starters the inj rate stock is 213.867 & with LS7 ma to get it in the ball park had to be 450.xxx inj rate.

But with how far out the reading is I'm hoping someone can shed some light on the maf freq tables & start point, when logging the exact car with standard maf the MGC is between 170 to 180 at idle, with the LS7 maf it's 70 to 74!
As that equates to around 150% I'm hoping either dividing or multiplying the entire MAF table for every freq & the start point by that amount should bring it ALL back in line?

As I see it I can tune it with the MAF readings it has but everything is going to be completely out for what is the normal range & going to need to change SO MANY reference tables & to get it even close to right will be a nightmare, so thinking if there's a mod to get the maf reference back into range it will save all that stuffing around?

Any thoughts, advice or ideas welcome as I could be completely wrong!

Just looking into the maf tables further, as I'm think if I multiply all of them by 2.5 it should bring it back to correct range...

But I noticed in the enhanced complete maf tabes it may be setup a bit different...
But with the corrected table as you can after table 9 the MSB, LSB & divider goes a bit wrong so again not sure if this is correct or not & obvioulsy added the FF in last 2 from where I moved the table to keep at at max reading high frequency???

something like that would be a good start. make sure you use the spreadsheet to do the calcs. You'll still probably need to take some logs on the car.

Perhaps if you have a bench pcm you could install the stock maf and the card maf inline with each other and run the card maf to a second computer, then log both as hz and mgc so you can cross reference the mgc from the factory maf against what hz the card maf is reporting at the same time and use that to build a new maf hz table. The factory maf would be a restriction you'd then need to remove but it should get you to a reasonable starting point. Once you've seen the shape of the curve you can extend it further beyond what the factory maf mapped and probably still end up in ballpark.

update: notice the first 3 columns would be handled by the spreadsheet. MAF Tables 14 Tuning.xlsm http://pcmhacking.net/forums/viewtopic.php?f=27&t=2518

Thanks yet again Antus, had a feeling that would be the case & unfortunately I don't have a bench PCM to test & cross reference as that would be a hell of a lot easier but yeah doing on a running car is a lot of stuffing around!

Don't think I did it correct as I broke it? it gets screwed up half way through?

I did 2.5 times the start point & then put 150 in for percentage difference of rest which should have brought it back to close?

Hmm not sure. It looks like the tables are going out of range but I dont know enough about the limits and how of that tables encoding.

i can't see that working, starting freq of 4725hz it wouldn't even run as idle is in 2000hz range, you can't get much more out of the MAF tables as you hit the FF limit.

When i put one on my car i just had to adjust the base injector rate, think my N/A went to 515, which then gave enough room to tweak using inj multi table, you can't get around the fact that the Cylair is now displaced lower because the hz input is now lower. I just moved the spark table left about 2 columns then retuned from there, apart from spark and fuel i didn't encounter any other issues really.

I thought you had to adjust some IAC, Idle & start up tables & scalars too?

Seems better to me if we get the maf reading closer to stock if we can?

that was before, when i had put bigger intake pipe, larger TB, port/polish, as it goes with any mods to increase airflow at crank/idle

Think you may have gone the wrong way with your starting point.
If the mgc is lower with the ls7 MAF the g/s must be lower at this point as well.
For this to happen with stock tables maybe it only has about 1500hz or less at idle.
Check your log at idle for MAF hz and adjust the start point down to match before playing with the curve.