metalman

iTrader: (3)

So, I am new to this fuel injection stuff and have been reading that speed density is the way to go on turbo set ups. What all is entailed in going speed density and not running MAF? What on the wiring will I need to change and so forth? I really appreciate any input.

SATAN

iTrader: (2)

Speed density is not necessarily always the best way to go. It depends on how much power you trying to make, how much boost and how quickly. In my tuning book Master EFI Tuner by Dan Maslic, he says that if you expect boost to come on quickly (say by 2500 rpm) then speed density is good. Or if you plan on running over about 9psi (if I remember right) then speed density is good. I have only ever run speed density, so that is what I do every time I do a build.

People will say that drivability suffers in a speed density tune. That is only true if the person tuning it did a poor job.

Other than that, it is simply a case of pulling the MAF wires out of the wiring harness. You will have to keep the air temp sensor wires though. They are wired into the maf. I got one of those books off of Ebay for $25 that gives you all the wire schematics and plug info. It REALLY helped out.

From there, you have to go in with your tuning program and set it up for speed density (this involves more reading). Again, my Master EFI Tuner book explains how to do this using HP Tuners and EFI Live.

MUSTANGBRKR02

iTrader: (91)

You have to get a 2 BAR MAP sensor or above and you just unplug the MAF. You have to get a appropriate OS for the PCM. If the PCM/harness is a f-body then nothing else, if it is a newer harness then a breakout harness for the IAT sensor may be needed.

If tuned proper you won't eve notice a difference without a MAF.

2nd Gen Fl 'bird

iTrader: (13)

I've researched this very topic and a lot are old posts. Some tuners that I've been talking to recently say if you're not planning on power above 800 then the MAF tune would be a lot more enjoyable on the street. They did agree on high boost and a restriction from the MAF once you get above the 800ish level. Are tuners able to tune more precisely now than 3-4 years ago? I know there are SD fans when it comes to boost but, drivability on the street makes a lot more sense. I'm starting to feel that some so called tuners can't tune that "deep" or just don't want to spend the time on a boosted, MAF tune. I didn't mean to jack the thread. It would be nice if someone who tunes on a REGULAR basis and sees a lot of different combos, give input.(Not saying anyone here is incompetent)

Sarg

iTrader: (6)

Actually I find maf very easy to tune. Sd is a bit more difficult to get 100 percent ironed out than a maf tune imho. As for streetability, I would say both can be quite streetable if done correctly.

96gt4.6

iTrader: (5)

I'm running Open Loop, Speed Density on my pile and it drives like stock.

Although, as stated above, the tuning work has to be done correctly for it to retain those characteristics.

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From my experience, when done properly SD is as good or better when compared to MAF in terms of driveability.

Sarg

iTrader: (6)

In some big cam ported head cars I think it can be even better. I know I tuned a turbo WRX that had big cams and hogged out heads that was very difficult on MAF tune and we switched to SD and it became very tame. Subaru does not use any form of SD from the factory. They are pretty much straight MAF with no real blending like the GM computers. When switching to a much longer intake tract, like a front mount intercooler (vs top mount factory) there is quite a lag between what the MAF reads and what is actually in the motor at that particular second.

I can only believe that this can be true on the GM vehicles as well. MAF sensor positioning would seem to be quite critical when doing a turbo car in terms of drivability. But on my car we plan on going straight 3 bar SD and not worrying about the MAF at all. I have tuned a variety of SD cars and provided they are thoroughly tuned on the VE table the drivability can be quite good! Again, on a highly modded car it can sometimes be much better than a MAF.