MAF or speed density
05-06-2010, 08:32 PM
#42
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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.
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.
thank you
05-12-2010, 02:21 AM
#45
I have 2 questions, i'm kind of learning in this topic so sorry if they are stupid questions!
1-can i use efi live to make a SD tune?
2-if i use the 100mm MAF can i still usind it above 500HP rage and i still going to have the ability to have good results with my tuning?
1-can i use efi live to make a SD tune?
2-if i use the 100mm MAF can i still usind it above 500HP rage and i still going to have the ability to have good results with my tuning?
05-12-2010, 10:15 AM
#46
I have 2 questions, i'm kind of learning in this topic so sorry if they are stupid questions!
1-can i use efi live to make a SD tune?
2-if i use the 100mm MAF can i still usind it above 500HP rage and i still going to have the ability to have good results with my tuning?
1-can i use efi live to make a SD tune?
2-if i use the 100mm MAF can i still usind it above 500HP rage and i still going to have the ability to have good results with my tuning?
If ou go SD, no need for the MAF, just get a longer hose to connect the lid the the TB.
Over on the EFILIVE forums, there is a write up to follow.. At the end just dont change a few settings and it stays in SD. Then just dial in your VE tables.
05-12-2010, 01:03 PM
#47
05-13-2010, 05:03 PM
#54
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He said it is very hard to explain in depth about how it works when the MAF is maxed out but basically fueling is controlled only by RPM after that point. It can not be determined how much load there is but it knows that it is above the maximum readable load so that value stays constant.
Basically it works, but it is not ideal. The tuner would have to build in a extra margin of safety into the fueling so that under different weather conditions and loads there is plenty of fuel. Methanol injection would help even further.
SD tunes will actually allow you to tune boosted VE tables.
Make sense?
05-13-2010, 09:28 PM
#55
I bought my 2002 SS used and the previous owner had it SD tuned. It ran great. It
felt strong from a launch. I bought it in August, well after a few months the night time temps dropped below 50 degrees and the car wouldn't start. I had to hold the pedal down a little to keep it from stalling out. Once the motor warmed up a little it surged until it was almost fully warmed up then it idled fine. If temp doesn't effect SD tuning then what was going on with my car? The next morning it did the same thing, so i pulled the IAT sensor out of the lid and warmed it up in the house and i was rolling the sensor in my hands. Then i reinstalled it back in the air lid and the car surged some but it did idle better and i didn't need to hold the pedal down. After that i just had a stock file flash in my PCM and it's been fine ever since. But i still think the car ran better with the SD tuning once it warmed up.
felt strong from a launch. I bought it in August, well after a few months the night time temps dropped below 50 degrees and the car wouldn't start. I had to hold the pedal down a little to keep it from stalling out. Once the motor warmed up a little it surged until it was almost fully warmed up then it idled fine. If temp doesn't effect SD tuning then what was going on with my car? The next morning it did the same thing, so i pulled the IAT sensor out of the lid and warmed it up in the house and i was rolling the sensor in my hands. Then i reinstalled it back in the air lid and the car surged some but it did idle better and i didn't need to hold the pedal down. After that i just had a stock file flash in my PCM and it's been fine ever since. But i still think the car ran better with the SD tuning once it warmed up.
05-13-2010, 10:46 PM
#56
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I bought my 2002 SS used and the previous owner had it SD tuned. It ran great. It
felt strong from a launch. I bought it in August, well after a few months the night time temps dropped below 50 degrees and the car wouldn't start. I had to hold the pedal down a little to keep it from stalling out. Once the motor warmed up a little it surged until it was almost fully warmed up then it idled fine. If temp doesn't effect SD tuning then what was going on with my car? The next morning it did the same thing, so i pulled the IAT sensor out of the lid and warmed it up in the house and i was rolling the sensor in my hands. Then i reinstalled it back in the air lid and the car surged some but it did idle better and i didn't need to hold the pedal down. After that i just had a stock file flash in my PCM and it's been fine ever since. But i still think the car ran better with the SD tuning once it warmed up.
felt strong from a launch. I bought it in August, well after a few months the night time temps dropped below 50 degrees and the car wouldn't start. I had to hold the pedal down a little to keep it from stalling out. Once the motor warmed up a little it surged until it was almost fully warmed up then it idled fine. If temp doesn't effect SD tuning then what was going on with my car? The next morning it did the same thing, so i pulled the IAT sensor out of the lid and warmed it up in the house and i was rolling the sensor in my hands. Then i reinstalled it back in the air lid and the car surged some but it did idle better and i didn't need to hold the pedal down. After that i just had a stock file flash in my PCM and it's been fine ever since. But i still think the car ran better with the SD tuning once it warmed up.
05-14-2010, 08:13 AM
#57
Just like a MAF tune.
The newest LSx cars do not have a VE table (that's how you SD tune) from the factory and run solely on MAF. For these applications, it is not a simple switch to convert to SD. This is why lots of newer vettes and stuff are MAF with FI.
The newest LSx cars do not have a VE table (that's how you SD tune) from the factory and run solely on MAF. For these applications, it is not a simple switch to convert to SD. This is why lots of newer vettes and stuff are MAF with FI.
05-14-2010, 09:58 AM
#58
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Also, you're right. I forgot to mention that I was referring to older-style GM PCM's.
05-15-2010, 07:04 AM
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Actually, the newer vettes do have an sd method of fueling, however it isn't layed out like a gen 3 or the early gen 4 ecu's, there are multiple tables which the ecu calculates to create a ve table which isn't visable.... this is why a member on hptuners forum created a table generator, so that u can data log afr error as in older ecu's and apply it to the ve table which is generated by another program and then it didvides back into the diferent tables again so u can apply it to the actual tune...
I tuned a friends 08 vette with a vortech, and did a maf tune, I did it this way simply because it was easier, didn't have to upgrade os, and newer ecu's and maf can read much more hp than older ones so there was no table fudging
I tuned a friends 08 vette with a vortech, and did a maf tune, I did it this way simply because it was easier, didn't have to upgrade os, and newer ecu's and maf can read much more hp than older ones so there was no table fudging