Noob Question difference between MAF / SD tune?
Thread Starter
CF Senior Moments Member
Joined: Jan 2004
Posts: 1,329
Likes: 1
From: Oklahoma City Oklahoma
Noob Question difference between MAF / SD tune?
I'm a noob - but have worked with computers extensively in my past/present. 
Trying to learn about this - what are the differences?
When do you want one or the other?
Is it either / or - or do some folks do both?
Are there some write ups about what you need to properly tune ?
wideband / 2bar / 3 bar - maybe the write ups explain these terms as well?
Trying to learn about this - what are the differences?
When do you want one or the other?
Is it either / or - or do some folks do both?
Are there some write ups about what you need to properly tune ?
wideband / 2bar / 3 bar - maybe the write ups explain these terms as well?
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Depends on the application--tell us more about your car--
But typically a MAF tune is fine for a DD / weekend racer type car--and one driven at different altitudes as the ECM will self adjust itself-
A "speed density" tune is great for a more serious racer type application or for a heavily modded car--OR for an early C5 with the 3.5 MAF where the MAF table does not go high enough to accomodate the extra incoming air---
But typically a MAF tune is fine for a DD / weekend racer type car--and one driven at different altitudes as the ECM will self adjust itself-
A "speed density" tune is great for a more serious racer type application or for a heavily modded car--OR for an early C5 with the 3.5 MAF where the MAF table does not go high enough to accomodate the extra incoming air---
Melting Slicks
Joined: Aug 2004
Posts: 2,237
Likes: 9
From: Springhill FL
MAF uses your maf sensor to measure the airflow into the engine and calculates load based on how much air is going in. SD uses the MAP sensor to measure manifold pressure and makes the calculations based on that. Guys running high boost usually go SD because the engine flows more air than a MAF sensor can accurately measure.
2 bar and 3 bar refer to what kind of MAP sensor they are running and tuning with. 1 Bar (Barometric pressure) is about 14.5PSI (earths atmosphere). Guys exceeding this much boost upgrade to a sensor with a higher range.... 2 bar or 3 bar
2 bar and 3 bar refer to what kind of MAP sensor they are running and tuning with. 1 Bar (Barometric pressure) is about 14.5PSI (earths atmosphere). Guys exceeding this much boost upgrade to a sensor with a higher range.... 2 bar or 3 bar
Thread Starter
CF Senior Moments Member
Joined: Jan 2004
Posts: 1,329
Likes: 1
From: Oklahoma City Oklahoma
Thanks guys - my A&A SC was installed and tuned by a shop almost 2 years ago and it doesn't make more than 1 bar I'm pretty sure.
It's a 2000 vert 6spd basically stock heads / engine.
Other than getting a "dyno sheet" I'm not sure what kind of mappings / settings the tune is. It runs great and I love to drive it pretty much every day!
Cheers,
However now I am more curious and will take the time to learn about tuning!
It's a 2000 vert 6spd basically stock heads / engine.
Other than getting a "dyno sheet" I'm not sure what kind of mappings / settings the tune is. It runs great and I love to drive it pretty much every day!
Cheers,However now I am more curious and will take the time to learn about tuning!
Melting Slicks
Joined: Mar 2004
Posts: 2,149
Likes: 6
From: NCCO Oklahoma
Thanks guys - my A&A SC was installed and tuned by a shop almost 2 years ago and it doesn't make more than 1 bar I'm pretty sure.
It's a 2000 vert 6spd basically stock heads / engine.
Other than getting a "dyno sheet" I'm not sure what kind of mappings / settings the tune is. It runs great and I love to drive it pretty much every day!Cheers,
However now I am more curious and will take the time to learn about tuning!
It's a 2000 vert 6spd basically stock heads / engine.
Other than getting a "dyno sheet" I'm not sure what kind of mappings / settings the tune is. It runs great and I love to drive it pretty much every day!
Cheers,However now I am more curious and will take the time to learn about tuning!
Standard Atmospheric Pressure is 1 ATM = 14.7 psia = 1.01325 Bar.
The MAP sensor is the Manifold Absolute Pressure sensor... and while you and I think of air as 0 psig as we breathe it, it sees it as about 14.7 psia. It measures the absolute pressure in the manifold... so while we think of a vacuum when compared to the air we breathe, the MAP sensor is actually reading the absolute pressure in the intake.
If you are running a boosted car, then you are going over 1 bar as soon as you make boost. If you are making 7 psi of boost, you are actually running: 14.7 psia + 7 psig = 21.7 psi. In that case, you would need a 2-Bar tune... all the way up to about 14.7 psig. (2 Bar is equal to about 29 psia.)
If you are running more than 14.5 psi of boost, you would need to step up to a 3-Bar tune. (3 Bar is equal to about 43.5 psia, or 29 psig.)
Does that make sense?
Last edited by Fasthotrod; Oct 14, 2010 at 03:58 PM.
Melting Slicks
Joined: Apr 2007
Posts: 2,787
Likes: 22
From: Lititz PA
1 Bar is equal to 14.5 psia.
Standard Atmospheric Pressure is 1 ATM = 14.7 psia = 1.01325 Bar.
The MAP sensor is the Manifold Absolute Pressure sensor... and while you and I think of air as 0 psig as we breathe it, it sees it as about 14.7 psia. It measures the absolute pressure in the manifold... so while we think of a vacuum when compared to the air we breathe, the MAP sensor is actually reading the absolute pressure in the intake.
If you are running a boosted car, then you are going over 1 bar as soon as you make boost. If you are making 7 psi of boost, you are actually running: 14.7 psia + 7 psig = 21.7 psi. In that case, you would need a 2-Bar tune... all the way up to about 14.7 psig. (2 Bar is equal to about 29 psia.)
If you are running more than 14.5 psi of boost, you would need to step up to a 3-Bar tune. (3 Bar is equal to about 43.5 psia, or 29 psig.)
Does that make sense?
Standard Atmospheric Pressure is 1 ATM = 14.7 psia = 1.01325 Bar.
The MAP sensor is the Manifold Absolute Pressure sensor... and while you and I think of air as 0 psig as we breathe it, it sees it as about 14.7 psia. It measures the absolute pressure in the manifold... so while we think of a vacuum when compared to the air we breathe, the MAP sensor is actually reading the absolute pressure in the intake.
If you are running a boosted car, then you are going over 1 bar as soon as you make boost. If you are making 7 psi of boost, you are actually running: 14.7 psia + 7 psig = 21.7 psi. In that case, you would need a 2-Bar tune... all the way up to about 14.7 psig. (2 Bar is equal to about 29 psia.)
If you are running more than 14.5 psi of boost, you would need to step up to a 3-Bar tune. (3 Bar is equal to about 43.5 psia, or 29 psig.)
Does that make sense?
