CALL911

iTrader: (17)

Well, from an experienced tuner like yourself, or a few other good tuners like Brian Better, I agree. But you would be amazed at the amount of tuners who do not know how to compensate after the MAF is maxed. Many told me I would simply have to go SD at that point because they didn't know how. Granted it may have been more difficult tuning it on my old LT1 PCM, but either way, there are more tuners out there that don't have experience than those who do.

96redcamaro

iTrader: (1)

Ed:

I have done some reading in the past from Greg Banish's books . It it seams like to me that you should be able to scale the MAF transfer function. But if you scale the MAF to see a larger amount of data you will lose resolution. Is this the correct way to go about it? Or is there another way of commanding the AF you want when the MAF is maxed out? Just wondering because i am about to buy a d1sc car that has an SD tune on it.

I just need to know if my research is heading in the right direction.

joecar

When you scale, you also have to shift down the contents of the air referencing tables (e.g. spark).

Ed Wright

iTrader: (1)

In boost??

T/A KID

iTrader: (12)

I do MAF Scaled tunes on boost builds all the time, rather do that than SD anyday. IT's Nice to have a 1024 g/sec limit or higher in a Gen 3 computer or even an LT1 computer, plus I get to control spark better in boost.

IF you don't want to scale you "could" manipulate the PE table where you max out the MAF at that RPM and increase fuel Via RPM by the PE table, the nature of a centri blower works well this way to be honest since the power is linear and so will the fuel control be.

CALL911

iTrader: (17)

So, to take another twist on this, what would be the downside of going SD? Good tuner to good tuner, could you get an SD tune as accurate as a MAF tune?

joecar

Across the whole range (since anything calculated from scaled MAF and/or VE is now also scaled... so airmass reference into spark table is scaled, so spark table has to be shifted along airmass axis).

Ed Wright

iTrader: (1)

And, what area of the spark table do you think is referenced in boost? And where do you think it would move to if the MAF tables is re-scaled?

You actually do this, or just talk about it?

LSX Power Tuning

iTrader: (4)

I promise you their MAF isn't 11+ years old with 100k + miles on it either. A new MAF works great but I see more and more bad MAF's in older ls1's like in 4th gens for example.

LSX Power Tuning

iTrader: (4)

If the tune is good you wont be able to tell if the maf is being used or its in sd. It will make the same hp, get the same fuel mileage and drive the same either way if both tunes are right.

Ed Wright

iTrader: (1)

But the odds of getting all the correction tables right during a one day dyno tune aren't great. My friend, now retired, who was an engineer/calibrator (or "tuner") for GM has some great stories about them actually hauling transporters full of development cars all over the country to get them in actual different weather conditions to dial in different areas of the correction tables in actual conditions. Those tables are different for "SD" versus a MAF calibration. His question is "How the hell can you correct all those parameters for Speed Density in one day?"

Btw, in response to your statement, yes you have to be smart enough to diagnose and replace a faulty MAF, just like any other component. If you had the time and capability to accurately calibrate those correction tables in actual conditions, it would still do nothing better than with a MAF. So, what's the point?

If there is no advantage to the MAF, why would people much brighter than you or I, (engineers at GM) put a MAF on those very high dollar race cars?

If you saw how many cars have come here to be changed back and re-tuned for MAFs after people get tired of their cars not running the same year round.....

I don't have one on my race car. FAST XFI doesn't support them. Factory PCMs don't run well much past 8500.

joecar

In boost it runs off the last column (depending on the g/cyl)... at low/mid load it runs off the center columns...

if the MAF and VE are scaled to 1/n then the g/cyl calculates to 1/n of its previous value, it now references a different column;

yes, we've done experiments with it, but I don't tune for a living, I'm not a professional (altho I do some consulting occasionally), I play with it in my own time, and I can stand to learn a whole lot more... I sure wish I had access to your friend.

Ed Wright

iTrader: (1)

Scaling the MAF table up in the boost, higher flow, area, it still runs off the bottom row of the spark table on boost. Light load/part throttle/driving down the street is not down in the middle of the spark table.

ddnspider

iTrader: (26)

Where is this data coming from? I've read Greg banish's book and watched the dvd's and have logged my boosted setup that maxes the maf at 4k rpms.....and it jumps to the highest g/cyl column in the spark table and the highest Hz cell in the maf curve. Outside of this you must pe rape if you don't scale the tune. After having said that, I am in the process of scaling the tune using an ls7 maf and one of the items from Greg's DVD is that you must scale the spark tables the same percentage as you scale all othe tables.

Ed Wright

iTrader: (1)

It comes from tuning more blown LS vehicles than you have probably seen. The bottom row IS the highest grams/cylinder row in the spark table.
Read what I said again.

Btw, your appear to be more impressed with that book than most people I know.

ddnspider

iTrader: (26)

I wasn't arguing that it isn't the highest row. I am arguing that on a scaled tune you would still automatically jump to the highest row. That would depend entirely on how much power the car is making and how much the tune is scaled.

Oh and I'm impressed with someone taking the time to teach others and step people through the tuning process instead of just making statements as gospel without explaining anything to the guys wanting to learn. Do I have much to learn, yup. But what helps us understand better is when a topic is explained and background information is provided. I could give you a specific equation for something but you'd learn a hell of a lot more if I explained the WHY it works.

Ed Wright

iTrader: (1)

Read it again, that is what I said. Scale it and in boost it's still going to the bottom (highest) row. NA is a different deal.

ddnspider

iTrader: (26)

I guess that's where I'm not understanding then. If a boosted setup hits 1.6g/cyl and I scale the tune 50% you're telling me that I will still jump to the 1.x row in the high octane spark table?

Ed Wright

iTrader: (1)

50%?? I give up.

ddnspider

iTrader: (26)

Seriously? I would point out that there are plenty of people who scale by 50% to give themselves room to grow so they don't have to go through the tedious exercise of changing all the tables more than once, but I guess that's dumb too. Ok so if a maf is maxed at 4k rpms, what would you scale it by?