Speed density tune...Why???
12-04-2011, 11:44 AM
#22
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I think for the GenIII guys running the MAF is probably your best bet. For GenIV, the VE table is alot more percise with a ton more cells, so I think you can get away from the MAF just fine if wanted. So far I am liking my SD tune, eventhough it still needs work.
Another thing, in closed loop my pcm would change the commanded AFRs while at part throttle, it would command a very lean mixture then drop down to super rich mixture while it should have been a straight 14.63 AFR. Well long story short, it doesnt do that any more in OLSD
Heres what the NNBS vs NBS VE tables compaired look like
Another thing, in closed loop my pcm would change the commanded AFRs while at part throttle, it would command a very lean mixture then drop down to super rich mixture while it should have been a straight 14.63 AFR. Well long story short, it doesnt do that any more in OLSD
Heres what the NNBS vs NBS VE tables compaired look like
Last edited by 2007chevy5.3l; 12-04-2011 at 11:51 AM.
12-04-2011, 12:30 PM
#26
I think for the GenIII guys running the MAF is probably your best bet. For GenIV, the VE table is alot more percise with a ton more cells, so I think you can get away from the MAF just fine if wanted. So far I am liking my SD tune, eventhough it still needs work.
Another thing, in closed loop my pcm would change the commanded AFRs while at part throttle, it would command a very lean mixture then drop down to super rich mixture while it should have been a straight 14.63 AFR. Well long story short, it doesnt do that any more in OLSD
Heres what the NNBS vs NBS VE tables compaired look like
Another thing, in closed loop my pcm would change the commanded AFRs while at part throttle, it would command a very lean mixture then drop down to super rich mixture while it should have been a straight 14.63 AFR. Well long story short, it doesnt do that any more in OLSD
Heres what the NNBS vs NBS VE tables compaired look like
12-04-2011, 02:54 PM
#30
I have to respectfully disagree that sd is more precise as the maf is a direct measurment of airflow unlike manifold pressure. Every street tune should start as sd to nail the ve first. At 97 kpa at wot, you can be at 6700 hz on the maf or 9700 hz. The maf isn't a table that has to be fooled. Gm calibrates the maf table by predetermined flow figures of the maf. When you change what goes on in front of or behind the maf, you likely will have to alter the maf table.
As Klug mentioned on big cam setups, sd may control idle fuelin better depending on where the maf is located. Also, sd may prove to be a little more responsive in most cases because a lot of people don't nail the ve, and the maf. Then you have 2 tables having to blend to get fueling correct at cruise and transient stages, it can cause it to be less responsive.
That being said my dd (99 cavalier) is sd from the factory. A lot of vehicles are. It doesn't have to have the maf, but on vehicles originally equipped with it, it is great.
As Klug mentioned on big cam setups, sd may control idle fuelin better depending on where the maf is located. Also, sd may prove to be a little more responsive in most cases because a lot of people don't nail the ve, and the maf. Then you have 2 tables having to blend to get fueling correct at cruise and transient stages, it can cause it to be less responsive.
That being said my dd (99 cavalier) is sd from the factory. A lot of vehicles are. It doesn't have to have the maf, but on vehicles originally equipped with it, it is great.
Ive also been very impressed with another similiar setup truck, SD tuned, running a decent sized but not too crazy blower cam that was N/A.
I dont feel you have to Go SD on an N/A setup, but if you do you should learn how to tune because as the weather changes so will some driveability items.
Now that its cold i have to apply a lil throttle to get my girl to fire up. I just havent tweaked that aspect yet as i wont be driving it this winter.