Someone explain speed density
03-23-2007, 03:28 PM
#1
Someone explain speed density I've looked and read about speed density and I understand a little bit of it. I am picking up a FAST 90/90 set up and Yank converter soon and also would like to get the car tuned for both. Is speed density something I should go ahead and do now? or should I wait? Heads and cam are in the cars very near future. What are the benefits of it? More Power? Thanks!
03-23-2007, 09:14 PM
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Speed density is nothing more than running without your MAF sensor. There are 2 different ways the PCM calculates fueling. One way is with the MAF sensor and the MAF table and the other uses the MAP sensor and a VE table. When the MAF is plugged in you are using a combination of the MAF and VE tables, SD just gets rid of the MAF table. Makes it easier to tune IMO.
Once you unplug your MAF you are in speed density. The pros and cons of SD have been discussed a lot on this site. Do not get caught up in the "Speed Density" name it will not make you faster or do anything special.
Once you unplug your MAF you are in speed density. The pros and cons of SD have been discussed a lot on this site. Do not get caught up in the "Speed Density" name it will not make you faster or do anything special.
03-23-2007, 09:22 PM
#6
Originally Posted by brad8266
Speed density is nothing more than running without your MAF sensor. There are 2 different ways the PCM calculates fueling. One way is with the MAF sensor and the MAF table and the other uses the MAP sensor and a VE table. When the MAF is plugged in you are using a combination of the MAF and VE tables, SD just gets rid of the MAF table. Makes it easier to tune IMO.
Once you unplug your MAF you are in speed density. The pros and cons of SD have been discussed a lot on this site. Do not get caught up in the "Speed Density" name it will not make you faster or do anything special.
Once you unplug your MAF you are in speed density. The pros and cons of SD have been discussed a lot on this site. Do not get caught up in the "Speed Density" name it will not make you faster or do anything special.
03-23-2007, 09:55 PM
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Originally Posted by bww3588
ive heard/read a LOT about SD tunes. ive also heard that changing altitudes/weather conditions ***** with a SD tune. but ive also heard that it doesnt. im split because i want to go with the GMPP ASA cam, and ive heard that its almost impossible on a 99+ car to make it run right without a SD tune. and i have a 98 so that makes it that much worse.
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03-23-2007, 10:01 PM
#8
Originally Posted by brad8266
That is FALSE!!! SD still uses closed loop operation and fueling will correct itself via LTFT's. If you run the car in open loop speed density then the tune can come off by major temp changes and other things but from what i have heard from people that run open loop tunes it isnt that bad at all and doesnt really require upkeep.
03-23-2007, 10:02 PM
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Originally Posted by bww3588
so if i keep her in closed loop, when i drive from Ohio to Myrtle Beach this summer, through the mountains of WV, VA and NC, i will be a-ok?
You dont have to do anything to keep it in closed loop either, the PCM goes in closed loop after the car is warmed up some.
03-23-2007, 10:07 PM
#10
Originally Posted by brad8266
Yeah the fuel trimming will kepp your fueling just fine, just like how the trims keep fueling in shape when you are still using the MAF.
You dont have to do anything to keep it in closed loop either, the PCM goes in closed loop after the car is warmed up some.
You dont have to do anything to keep it in closed loop either, the PCM goes in closed loop after the car is warmed up some.
