Speed Density?
Speed Density? What exactly is Speed Density i hear alot of ppl talking about converting to it...what are the benefits? whats the difference from what the car runs now? Some information would be greatly appreciated 
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
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From: Lake Zurich, IL
Speed Density is basically running w/out a MAF and relying on the IAT and MAP Sensors to tell the PCM how much air is entering the motor....
Advantages:
No MAF means less restriction of intake charge
No MAF means 1 less table to tweak to try to get inline w/existing mods
No MAF means no need to purchase an aftermarket MAF or a larger diameter MAF
Disadvantages
More time consuming to tune
IAT temperature is much more critical (being reported accurately) than w/a MAF tune
93 Camaros and Firebirds were Speed Density from the factory I believe?
Once dialed in no difference.. you're using the MAP Sensor and RPM... given that you know what cell the PCM is looking at ... then you can look at what the LTFTs are for that cell.. if + then the PCM is adding fuel which means more air is entering for that value than the PCM thinks is...
Our cars failover to Speed Density when they detect a MAF problem (or if you force an error)
Advantages:
No MAF means less restriction of intake charge
No MAF means 1 less table to tweak to try to get inline w/existing mods
No MAF means no need to purchase an aftermarket MAF or a larger diameter MAF
Disadvantages
More time consuming to tune
IAT temperature is much more critical (being reported accurately) than w/a MAF tune
93 Camaros and Firebirds were Speed Density from the factory I believe?
Once dialed in no difference.. you're using the MAP Sensor and RPM... given that you know what cell the PCM is looking at ... then you can look at what the LTFTs are for that cell.. if + then the PCM is adding fuel which means more air is entering for that value than the PCM thinks is...
Our cars failover to Speed Density when they detect a MAF problem (or if you force an error)
9 Second Club
Joined: Nov 2001
Posts: 1,445
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From: Bay Area, CA
its a tune without the maf, it relys on your map sensor and a few other variables to control fueling, its a very tedious job, and is not for everyone. early mustangs pre 87, and 93 and older fbodies that were fuel injected were also considerined speed density cars.....
try searching this section you will find tons of info, how to put your car in to SD mode, how to tune it, why people do it(maf limitations/restrictions), etc.
try searching this section you will find tons of info, how to put your car in to SD mode, how to tune it, why people do it(maf limitations/restrictions), etc.
I did a bit of searching and i remember someone saying you max out you MAFS at about 570hp...what happens when you max it out? and when you do max it out is speed density the only other option?
Thanks
~Tom
Thanks
~Tom
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Originally Posted by Nickn20
horist 85-93f-bods were SD, mustangs 85-86 were also and CA model 87s were SD while all the other states had mafs that year I believe.
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yea i know im digging up an old thread but anyways
so you guys are saying if i unplug the MAF it will go into SD, on a stock tune is that bad, better, or the same, could i run a faster time at the track with the MAF unplugged on a stock tune?
so you guys are saying if i unplug the MAF it will go into SD, on a stock tune is that bad, better, or the same, could i run a faster time at the track with the MAF unplugged on a stock tune?
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Verdad Gallardo TECH Addict
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Originally Posted by LiquidFire350
yea i know im digging up an old thread but anyways
so you guys are saying if i unplug the MAF it will go into SD, on a stock tune is that bad, better, or the same, could i run a faster time at the track with the MAF unplugged on a stock tune?
so you guys are saying if i unplug the MAF it will go into SD, on a stock tune is that bad, better, or the same, could i run a faster time at the track with the MAF unplugged on a stock tune?
Originally Posted by Another_User
On a stock tune it is bad. Your car will run like crap. I don't know if it will compensate or not because it is not tuned from the factory to run in SD mode.
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Originally Posted by TAQuickness
On a bone stock car, in the event the MAF were to actaully fail or gets unplugged, the PCM will compensate by falling back to the VE table and reverting to the low octane spark table, hence running like crap.
I wanna see someone who's got a sweet SD tune and their MAF calibrated well hit the dyno... I wanna see the difference b/w a descreened/ported/polished MAF vs no MAF at all. I should done this awhile back when i was on the dyno dammit... 
I bet the gain is quite minimal, maybe even insignificant... 
With that said, SD is a great operation to get your tune inline, although I'm a proponent of going back to MAF operation once SD tuning is complete.
I bet the gain is quite minimal, maybe even insignificant... With that said, SD is a great operation to get your tune inline, although I'm a proponent of going back to MAF operation once SD tuning is complete.
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From: Fredericksburg, VA
Originally Posted by txhorns281
I wanna see someone who's got a sweet SD tune and their MAF calibrated well hit the dyno... I wanna see the difference b/w a descreened/ported/polished MAF vs no MAF at all. I should done this awhile back when i was on the dyno dammit... I bet the gain is quite minimal, maybe even insignificant...
With that said, SD is a great operation to get your tune inline, although I'm a proponent of going back to MAF operation once SD tuning is complete.
I bet the gain is quite minimal, maybe even insignificant... With that said, SD is a great operation to get your tune inline, although I'm a proponent of going back to MAF operation once SD tuning is complete.
Originally Posted by BlackCamaroSS02
What exactly is Speed Density i hear alot of ppl talking about converting to it...what are the benefits? whats the difference from what the car runs now? Some information would be greatly appreciated
Originally Posted by Bryan Wilkinson
I was using the MAF sensor until recently and switched to the 2 bar HP Tuners setup which is speed density, and driveability improved 100% and so did the effort requried to get it tuned right.
Originally Posted by txhorns281
With you setup, I would imagine trying to tame any airflow calculation would be difficult...
On the Dynograph, the A/F curve and Power curves were good but not smooth when I was using the MAF. When I switched over, everything got smooth.
When I am not having to have the car go through its yearly inspection, using the stock computer I cut off the factory o2's and run in open loop mode. When I go to get inspected I cut the 02's back on.
I have the factory 02's in the front and the PLX wide bands in the rear for the gauges and tuning purposes. The car gets about 25 mpg on the hwy.
