Zac_Speed

iTrader: (4)

Can anyone explain to me the difference between a normal tune and a speed density tune? About all that I know is the MAF is gong on the later.

joecar

SD tune uses the VE table exclusively (whereas MAF tune uses: MAF above 4000 rpm, both MAF and VE below 4000 rpm).

Zac_Speed

iTrader: (4)

So are there any draw backs to an SD tune???

Zac_Speed

iTrader: (4)

Class... Anyone...

Mike454SS

iTrader: (4)

I've posted a lot about it before (if you search posts from my name with "speed density" you will find them).

Short of that is...I don't feel there are any drawbacks at all. I've had excellent results tuning speed density on everything from mild to wild. All of the naysayers usually don't understand how to properly tune/calibrate it.

joecar

No drawbacks...

You may have to edit the transmission failsafe/max pressure tables to ignore a MAF DTC or two.

Think about this:

with a CLMAF tune, PCM reads airflow 12" to 20" upstream of combustion chambers, and reads NBO2's 20" to 40" downstream of the chambers... i.e. it is calculating airmass/fueling using future/past values...

with an OLSD tune, the PCM calculates airmass/fueling based on instantaneous table lookups (i.e. you have to first fine tune the tables using a wideband)... so even tho CLMAF and OLSD make the same HP and TQ numbers, OLSD gives quicker throttle response.

Also note that the VE table's units are g*K/kPa... i.e. it is normalized/corrected for temperature and pressure.

Both ways are good and have their own "features".

My $0.02.