Drewhelm

iTrader: (7)

Great post! I'm new to FI and and learning daily. Looks like SD is the way to go....atleast for me.

conan

iTrader: (5)

I would never take my car to sea level and go WOT with out a re tune but the 1,000 ft in elevation change i see on a daily basis doesn't seem to affect my wide band. Now I have drove on a road that goes to 10,400 ft and I noticed my wide band was on the rich side.

good info ^^^

youngrigo

I say run a MAf and a 2 or 3 bar set up.... Run the MAF for the crusing and then for the Wide open runs go off of the SD. Because i like to take my car anywhere. Go from Sea level to 8,000 ft up

moddedta

i just like the idea of the sd cause it would allow me to use an atmospheric bov on my supercharger where do i get the 2 or 3 bar map sensor that I would need, or would I even need it with only 9psi? also, what would be the best way to control meth with boost?

1971ls1

iTrader: (4)

i know speed inc can set you up with a SD configuration im just not sure of the price. so i guess SD is the way to go

jomomma

iTrader: (39)

A lot of people use the map from a ss cobalt. I had one in my turbo'd ls swap.

barnat

iTrader: (59)

You just change out your stock LS1 MAP sensor with a 2 or 3 bar MAP sensor depending on the amount of boost your running. I went with a GM 2 bar Cobalt sensor which is more percise then a 3 bar from what ive heard and read on here and is good to 15 PSI and takes the same plug as our F bodys .After the tune ,you just tuck your mass air flow plug up out of the way as you wont plug it back in to your mass air flow sensor after the tune is complete

99LS6SS

iTrader: (4)

I've heard the stock MAF is pegged at something like 14,000 hZ. So if you're not peggin out the MAF, then why not use it? Seems it would be more accurate

elias_799

iTrader: (8)

^^^it is a computer problem not a maf problem. the computer is not able to read the maf after a certain level (usually 500whp)

yea if you are making under 500whp i would defiantly keep the maf, but most FI cars max out the maf

OldskOOL01z28

iTrader: (3)

Great post, Ive been looking for an answer to this question myself....just wondering where is the stock MAP sensor located on a 2001 f body ls1?....friend of mine has a FAST intake on a ls1 GTO and they put the MAP sensor right on top of the manifold behind the TB.

boosted LT1

iTrader: (3)

I know on an LT1 the MAF is still active when in SD. The wiring still provides 5volt to the sensor, the output is not read by the computer but still available for a Meth controller.

I have used SD and MAF. Each has 'advantages'. The MAF is limited in the amount of AFGS (Air Flow Grams/second) to ~500 which is said to represent ~500 RWHP.

So if you are using MAF at the point the MAF maxes out you lose the ability to use the MAF to determine that the Air flow changed from say 500 to 600.

SS101

iTrader: (2)

so how is it that you can run both MAF and SD...this intrigues me

boosted LT1

iTrader: (3)

Ok I said it poorly I meant to say I have used both Speed Density and MAF.

There is not a mode that I am aware of to be in SD and use the MAF. HOWEVER, what do we call a setup that is in MAF mode, but is locked in open loop?

You can lock open loop by setting the temperature for entering closed loop to say 130 degrees C.

1971ls1

iTrader: (4)

incase anyone is wondering Speed Inc sells a map sensor and harness extension for about $120

jamnut

iTrader: (4)

Going from a high da to a low da at the same altitude killed my buddies SD blower car.

elias_799

iTrader: (8)

^^^what do you mean by DA ?

1971ls1

iTrader: (4)

DA means density altitude

TTI George

I like sd for a fi tune but its nice to have a decent maf tune for when emissions come around if you gotta deal with it.

1971ls1

iTrader: (4)

im lucky enough that my truck is a 71 im exempt from emissions

cjmatt

iTrader: (4)

This thread is full of bad info...

Speed Density is beneficial when...

1) you max out the MAF
2) you want an atmospheric BOV
3) you want to tune yourself and go boosted

If you have a proper SD tune, you wont go lean when it gets colder or you go down in elevation. The computer has an IAT (intake air temp) multiplier to compensate. Also, your MAP sensor takes altitude out of the equation as its compensating for air pressure

Speed Density takes the air temp, air pressure, and RPM and feeds it into an algorithm with the volumetric efficiency to determine the same value that the MAF is providing. Once the MAF no longer can provide the readings you need, you need to let SD do it for it.