6.0ltrS10

iTrader: (2)

Ok, I'm new here to the ls1 stuff. Why is it I see all of the cars tuned with a s/d tune. Are the gm maf sensors junk? I have done quite a few email tuning on lightnings and other various mod motors, my own was a v10 with a turbonetics t4 turbo, I used the slot style maf from Pmas. Are the GM pcm's not up to par for maf tuning? I'm starting a twin turbo forged 370 build and was wondering about tuning issues with it. Any info is greatly appreciated.

Frost

iTrader: (45)

No the PCMs work great. Unlike the Ford hardware, there are two layers to the airflow model. OEM, the PCMs use a mix of SD and MAF for airmass estimation. There are several reasons to use SD such as FI that maxes out the MAF (512g/s for GenIII) or the desire to have that snappy throttle feel (like a well tuned carb car) that is just not there in MAF mode. That 370 will want a 2 or 3 bar MAP sensor and accompanying OS (which will be SD).

6.0ltrS10

iTrader: (2)

What do you mean by FI that will max out the maf? What if I use my hpx maf that won't max out, even in a 4" tube at 1000whp? Also you stated OP, what is this?
Thanks for all the info

Frost

iTrader: (45)

The MAF isn't actually the limit, the PCM is the limit. 512g/s for the MAF curve.... you can try the old timey scaling trick with the injectors and airflow tables, but we don't have access to all of them in ANY package. The result is goofiness here or there. Most of the MAF-obsessed users here are bolt-ons guys that are determined that their "MAF is a restriction"

I didn't say OP, not sure what you mean.

6.0ltrS10

iTrader: (2)

It was the Accompanying OS stuff? What do you mean by that?

BLK02WS6

iTrader: (2)

He is talking about using a custom operating system from one of the tuning software suites... those allow 2 & 3 bar speed density tuning. That is the best way to go with a forced induction setup. I prefer EFILive, but HP Tuners offers custom operating systems as well...

Schwanke Engines

iTrader: (1)

If you need tuning software, give me a call. We are an EFI Live dealer and I wouldn't choose anything other than EFI to tune a car.

6.0ltrS10

iTrader: (2)

Thanks for the great info guys, I have been wanting to get into the tuning myself. I always used a guy named Joe from tricktuners.com He would email me a base tune, I would datalog using SCT datalogger and my xcal3 or a SCT livewire, Usually after the 3rd datalog the tune was set. I look forward to all the LS1 and EFI live has to offer.

MUSTANGBRKR02

iTrader: (91)

Hpt is very capable also, but either is a good choice.

darkhorizon

I have always been a MAF guy myself after setting up a more than a few LS1 turbo setups.

The problem with mafs can be easily fixed via maf translators, or bigger tubes. There are more than a few maf translators out there that would easily fix the "issues" that frost was talking about in terms of drivability behind a really goofy maf setup. You can also skew injectors based on maf size and take out the issues with the maf reading "incorrectly" for load calculations and deal with the maxxed out maf table values easily.

I have yet to find any reason to go SD, but I have not made 1000whp+ yet. So far the maf setups I have used work great up to 800/900whp. The biggest maf setup I have used was a stock LT1 maf with a fixed ratio translator on it. That setup was tuned for 40# injectors, even though there were 60# injectors on it. The maf table resembled stock.

Ed Wright

iTrader: (1)

There is no advantage to speed density for a normally aspirated engine. None. A properly tuned MAF system is just as "snappy" as any other. Being limited to store-bought tuning software would make it a little more difficult. I have undone more of these deals for people than I can count. It comes down to understanding how GM uses the V.E. and MAF together.

It's very simple to make the GMs all-MAF like the Fords. Nothing to it, many tuners do it that way. (I don't) Not one thing wrong with that method.

Even worse than speed density, speed density-open loop. Don't get that one at all. I have yet to undo one of those and not improve both overall drivability and fuel economy.

69 Ghost

What Ed said. MAF is an accurate flow meter. Better than SD in my opinion.

darkhorizon

Does HPT or efi live have the transient fueling VE reference switch available? On my v6's I work with you can enable or disable the VE table transient functionality. I have a good idea on how to tune the VE properly in the LS world, but its only in theory for now.

Frost

iTrader: (45)

Yes you can easily put the car all 'on the MAF'.

darkhorizon

I have "all maf" enabled on my v6 tunes, only because I have never found the real link between the VE-transient and the maf table. It seems to only effect things in really small ways on the V6, from what I understand on the LS engines it is a much bigger deal.

JDMC5

iTrader: (3)

the LS engines are easier to tune than the 3800's in my experience.

darkhorizon

They are about the same.

The LSx VE tables are more of a pain in the ***, as well as the extra injector constants. Also VATs is a bit less flexible between all LSx cars as well.

JDMC5

iTrader: (3)

I've never needed to mess with VATS so doesn't bother me. Also, I've had less trouble with the LS VE.

LSxPwrDZ

iTrader: (4)

All this SD vs MAF is goofy to me. It all depends on the setup! To tune one 'right' to me wouldnt be raping the injector tables to keep the 512g/sec limit down. I like my PCM to read actual numbers. My 403 setup is going to have to be SD because it maxxes out the MAF sensor in frequency (I know a different MAF setup would cure it) and the 512g/sec limit! It is also running open loop. Guess what it run's perfectly fine!

The problem is most tuner's don't spend the amount of time on the VE tables and setting up other areas in the tune to make it run consistant and right! A tune on a heads/cam car usually take me all day long to make it run how I like it to.

I'm not saying that SD is better! I've kept running my MAF sensor on my car and with multiple tests there is absolutely 0 performance difference up until the MAF flatlines and maxxes out!

If your going boost, go SD! Also if you use HPT and use the 1bar SD OS there is a Alpha-N multiplier table that allows you to modify fueling based on RPM vs TPS% as well! This is very very useful in fine tuning high load low rpm points and other various points on the map that are phenicky with larger camshafts.

vmapper

iTrader: (8)

Well put, but as you said, it depends on the situation. I drive where elevation changes from 3400 down to sea level. I dont think a well tuned 3400ft SD tune is going to run well at sea level or am I missing something here?

I prefer to run Pure MAF right now, NA, am going FI real soon here and wanted to keep MAF ECM calculations. (VE blend only for under 2800rpm - drivability range) Will be doing a constant speed tuning for those RPM VE cells.)

so if my 512g/sec it hit, you can scale the MAF table with the IFR table? And every other table that would be affected?
Is there a list of the tables for change when scaling the MAF / IFR tables?
also, then the MAF signal limit would the limiting factor no?