MAF vs SD
Thread Starter
Teching In
Joined: Aug 2021
Posts: 22
Likes: 4
MAF vs SD Alright y'all I'm about to open the can of worms. I feel like this topic is as heavily debated as what kind of oil is best.
SO, I currently have a bone stock LS1 in a 4th gens T/A and to start off with I'm doing some very basic upgrades of LT headers, air lid and CAI, and a LS6 intake manifold. After that ill be getting a tune, should I switch over to SD since my tuner will be tuning the car anyways? This is a street build that eventually I'm hoping to achieve about 550 whp, I will be doing heads and a cam in the future and I read an SD is better when you have a larger cam. Should I switch over now? Do I need a whole new PCM to be able to switch over? Would it actually be a upgrade? Treat me like a noob, because I'm still very intermediate in this kind of stuff. Also, I live in OKC and rarely leave the state to a point where elevation would be a issue. Thanks!
SO, I currently have a bone stock LS1 in a 4th gens T/A and to start off with I'm doing some very basic upgrades of LT headers, air lid and CAI, and a LS6 intake manifold. After that ill be getting a tune, should I switch over to SD since my tuner will be tuning the car anyways? This is a street build that eventually I'm hoping to achieve about 550 whp, I will be doing heads and a cam in the future and I read an SD is better when you have a larger cam. Should I switch over now? Do I need a whole new PCM to be able to switch over? Would it actually be a upgrade? Treat me like a noob, because I'm still very intermediate in this kind of stuff. Also, I live in OKC and rarely leave the state to a point where elevation would be a issue. Thanks!
Last edited by imaswfan; Jun 2, 2022 at 11:25 AM.
As long as your tuner, actually tunes properly, and doesn't just MAF rape it since your keeping the MAF, you probably should keep the MAF, but that's not really the actual question you asked.
On my personal stuff, it's SD. It's going to run the same either way if it's tuned correctly. A good tuner, should be able to get a majority of the cams you'll pick, to start, idle, tip in and run very good with the MAF.
I noticed you said something along the lines of a fairly big cam, do you know what your going with, or around what size? What's big to you?
On my personal stuff, it's SD. It's going to run the same either way if it's tuned correctly. A good tuner, should be able to get a majority of the cams you'll pick, to start, idle, tip in and run very good with the MAF.
I noticed you said something along the lines of a fairly big cam, do you know what your going with, or around what size? What's big to you?
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
Likes: 179
From: Virginia
MAF is better for a street car with mild mods. Really, either is fine since you can choose multiple options. There are four typical ways to skin this cat:
MAFOL
MAFCL
SDOL
SDCL
There is also blended “stock settings” which simply uses both models.
The “OL” and “CL” are “Open Loop” and “Closed Loop”, and that is simply a reference to if your O2 sensors are on or not. They are “on” in CL.
Bear in mind though that the stock O2’s get pretty inaccurate once they are above or below about one value from stoich. Simply means they don’t work so well if you are out of the 13.5 - 15.5 AFR range.
Since SD does in fact change with weather conditions, which is extremely difficult to pin down with the IAT/ECT bias, that means MAF will stay more accurate throughout the year.
SD is awesome for rowdy builds because it’s a straight forward mathematical lookup table, and whatever cell you are in will be what you tell it to be. Tends to have less issues with narly cams and turbulent slow moving idle air. Big cams reduce vacuum. but since it is a lookup table, there’s not enough corrections to keep it dead on through the year. The O2’s can make up for it, but only reliably if you aren’t outside the window mentioned above.
Hopefully that makes sense. No argument here. Do what you want, both work great if you tune them right. At a certain point though you will run out of MAF, which is why big HP cars run SD only pretty much. Though with newer generation ECM’s, the limit is pretty damn high lol.
MAFOL
MAFCL
SDOL
SDCL
There is also blended “stock settings” which simply uses both models.
The “OL” and “CL” are “Open Loop” and “Closed Loop”, and that is simply a reference to if your O2 sensors are on or not. They are “on” in CL.
Bear in mind though that the stock O2’s get pretty inaccurate once they are above or below about one value from stoich. Simply means they don’t work so well if you are out of the 13.5 - 15.5 AFR range.
Since SD does in fact change with weather conditions, which is extremely difficult to pin down with the IAT/ECT bias, that means MAF will stay more accurate throughout the year.
SD is awesome for rowdy builds because it’s a straight forward mathematical lookup table, and whatever cell you are in will be what you tell it to be. Tends to have less issues with narly cams and turbulent slow moving idle air. Big cams reduce vacuum. but since it is a lookup table, there’s not enough corrections to keep it dead on through the year. The O2’s can make up for it, but only reliably if you aren’t outside the window mentioned above.
Hopefully that makes sense. No argument here. Do what you want, both work great if you tune them right. At a certain point though you will run out of MAF, which is why big HP cars run SD only pretty much. Though with newer generation ECM’s, the limit is pretty damn high lol.
Trending Topics
Launching!
Joined: Aug 2017
Posts: 231
Likes: 111
Hci ls1 builder here— my exp
i went to 5 different tuners w my sd setup.
idled terrible
hp tq drivability varied w weather
i smelled like gas all the time…. It has cats.
I got tired of chasing tail and wasting $$$…
put mass air sensor back in…. Fresh Maf tune from mail order tunes… and car now drives idles like a stock c5 z06….
my experience.
i went to 5 different tuners w my sd setup.
idled terrible
hp tq drivability varied w weather
i smelled like gas all the time…. It has cats.
I got tired of chasing tail and wasting $$$…
put mass air sensor back in…. Fresh Maf tune from mail order tunes… and car now drives idles like a stock c5 z06….
my experience.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Hci ls1 builder here— my exp
i went to 5 different tuners w my sd setup.
idled terrible
hp tq drivability varied w weather
i smelled like gas all the time…. It has cats.
I got tired of chasing tail and wasting $$$…
put mass air sensor back in…. Fresh Maf tune from mail order tunes… and car now drives idles like a stock c5 z06….
my experience.
i went to 5 different tuners w my sd setup.
idled terrible
hp tq drivability varied w weather
i smelled like gas all the time…. It has cats.
I got tired of chasing tail and wasting $$$…
put mass air sensor back in…. Fresh Maf tune from mail order tunes… and car now drives idles like a stock c5 z06….
my experience.
My truck has been SD for years. I daily drive it for years. In all honesty, if the tune is correct, you should be able to unplug your MAF while it's running, and have absolutely zero idea it happened, other than getting a mil light.
The idle shouldn't change, the smell shouldn't change, the driveability, shouldn't change.
The MAF is simply another sensor to help correct for small variances in altitude, temperature, and discrepancies in airflow. That's it, nothing more, nothing less.
Now you can "feel" a seat of the pants difference between the 2, and I really can't explain that, because the car will run identical numbers if the tune is right. I've spent quite a bit of time with this, and it's not just my opinion, it's been said over and over by others with way more experience than me.
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
Likes: 179
From: Virginia
Well that's my point. Most "so called tuners" really don't know much, or don't take the time.
My truck has been SD for years. I daily drive it for years. In all honesty, if the tune is correct, you should be able to unplug your MAF while it's running, and have absolutely zero idea it happened, other than getting a mil light.
The idle shouldn't change, the smell shouldn't change, the driveability, shouldn't change.
The MAF is simply another sensor to help correct for small variances in altitude, temperature, and discrepancies in airflow. That's it, nothing more, nothing less.
Now you can "feel" a seat of the pants difference between the 2, and I really can't explain that, because the car will run identical numbers if the tune is right. I've spent quite a bit of time with this, and it's not just my opinion, it's been said over and over by others with way more experience than me.
My truck has been SD for years. I daily drive it for years. In all honesty, if the tune is correct, you should be able to unplug your MAF while it's running, and have absolutely zero idea it happened, other than getting a mil light.
The idle shouldn't change, the smell shouldn't change, the driveability, shouldn't change.
The MAF is simply another sensor to help correct for small variances in altitude, temperature, and discrepancies in airflow. That's it, nothing more, nothing less.
Now you can "feel" a seat of the pants difference between the 2, and I really can't explain that, because the car will run identical numbers if the tune is right. I've spent quite a bit of time with this, and it's not just my opinion, it's been said over and over by others with way more experience than me.
Agree completely with this. Not every tuner takes the time to go through the FULL process, which is tuning SD first, then the MAF. Some just disable SD and tune the MAF only.
Can’t say I’m not guilty of that myself, when pressed for time and wanting to get a customer’s vehicle drivable in a matter of a few runs around the block. If that’s the case MAF is faster and easier to tune. I made the customer aware of that though, and told him if his MAF every crapped out his car would run like ***. He asked for a quick tune, and he got one lol.
A good SD-only tune will feel peppier than a blended (MAF + SD) tune, but the SD tune may cause very slightly less accurate fueling with weather changes. As others have stated, if the MAF fails, the PCM will set a code and run purely off the 'backup' SD calibration; if the SD calibration is significantly off you'll definitely feel it. With larger power increases, I definitely wouldn't want to run too lean as a result of not calibrating all fueling tables. I did a top-end cleaning once through a vacuum line, while running SD-only, and the top end cleaner seemed to have damaged the MAP sensor at the front of my LS3 intake and causing whacked MAP readings. That was a PITA. As much as possible, I like to use both VE & MAF as a failover mechanism.
I'd request to properly tune both VE (aka SD) and MAF (with a straightening screen) while you are within the constraints of your PCM limits. If you eventually max out the MAF airflow (512 g/s) supported by your PCM, then you can upgrade to a larger diameter MAF. But the PCM also has a max MAF frequency of ~12kHz which you cannot work around. IIRC, at that point you should remove the MAF and go pure SD. You can also scale the airflow tables later if you exceed other airflow limits. Oh, if you have a '98 PCM then they should tune both primary and secondary VE tables.
Watch Chopper's YouTube videos to get an understanding of what to expect the tuner to do before you show up for your appointment
I'd request to properly tune both VE (aka SD) and MAF (with a straightening screen) while you are within the constraints of your PCM limits. If you eventually max out the MAF airflow (512 g/s) supported by your PCM, then you can upgrade to a larger diameter MAF. But the PCM also has a max MAF frequency of ~12kHz which you cannot work around. IIRC, at that point you should remove the MAF and go pure SD. You can also scale the airflow tables later if you exceed other airflow limits. Oh, if you have a '98 PCM then they should tune both primary and secondary VE tables.
Watch Chopper's YouTube videos to get an understanding of what to expect the tuner to do before you show up for your appointment
Well that's my point. Most "so called tuners" really don't know much, or don't take the time.
My truck has been SD for years. I daily drive it for years. In all honesty, if the tune is correct, you should be able to unplug your MAF while it's running, and have absolutely zero idea it happened, other than getting a mil light.
The idle shouldn't change, the smell shouldn't change, the driveability, shouldn't change.
The MAF is simply another sensor to help correct for small variances in altitude, temperature, and discrepancies in airflow. That's it, nothing more, nothing less.
Now you can "feel" a seat of the pants difference between the 2, and I really can't explain that, because the car will run identical numbers if the tune is right. I've spent quite a bit of time with this, and it's not just my opinion, it's been said over and over by others with way more experience than me.
My truck has been SD for years. I daily drive it for years. In all honesty, if the tune is correct, you should be able to unplug your MAF while it's running, and have absolutely zero idea it happened, other than getting a mil light.
The idle shouldn't change, the smell shouldn't change, the driveability, shouldn't change.
The MAF is simply another sensor to help correct for small variances in altitude, temperature, and discrepancies in airflow. That's it, nothing more, nothing less.
Now you can "feel" a seat of the pants difference between the 2, and I really can't explain that, because the car will run identical numbers if the tune is right. I've spent quite a bit of time with this, and it's not just my opinion, it's been said over and over by others with way more experience than me.
The "seat of the pants" difference you note is typical of GM's "blended" air model. This model reverts to SD for fast throttle transitions. This means that if a car is only MAF tuned for aftermarket changes, then the throttle transition changes will not be correct. When you change to an SD only tune, it seems more responsive during quick throttle transitions. You could in theory tune the MAF and lots of additional modifier tables to get the same response, but nobody bothers. The only people who put that much effort into MAF tunes are usually tuning MAF only vehicles such as Ford Lightnings.
I’m tuning a mild cam LS3 right now. I put a 24x wheel in it when I built it.
Round 85mm MAF with the screen. MAF only. I always start that way.
P01 starting from an 02 Camaro OS.
Fired and ran well first turn of the key.
Dialed in the idle etc ($40 eBay 92mm TB with sensors)
First drive the trims were all negative but just a few %. Nice.
Now I’m doing WOT tuning with the wideband.
What I notice, and have noticed on my corvette, is a flat fuel line in second or third gear, is lean in low gear. Using the same MAF cells. This LS3 is doing the same.
It bugs me.
Round 85mm MAF with the screen. MAF only. I always start that way.
P01 starting from an 02 Camaro OS.
Fired and ran well first turn of the key.
Dialed in the idle etc ($40 eBay 92mm TB with sensors)
First drive the trims were all negative but just a few %. Nice.
Now I’m doing WOT tuning with the wideband.
What I notice, and have noticed on my corvette, is a flat fuel line in second or third gear, is lean in low gear. Using the same MAF cells. This LS3 is doing the same.
It bugs me.
I’m tuning a mild cam LS3 right now. I put a 24x wheel in it when I built it.
Round 85mm MAF with the screen. MAF only. I always start that way.
P01 starting from an 02 Camaro OS.
Fired and ran well first turn of the key.
Dialed in the idle etc ($40 eBay 92mm TB with sensors)
First drive the trims were all negative but just a few %. Nice.
Now I’m doing WOT tuning with the wideband.
What I notice, and have noticed on my corvette, is a flat fuel line in second or third gear, is lean in low gear. Using the same MAF cells. This LS3 is doing the same.
It bugs me.
Round 85mm MAF with the screen. MAF only. I always start that way.
P01 starting from an 02 Camaro OS.
Fired and ran well first turn of the key.
Dialed in the idle etc ($40 eBay 92mm TB with sensors)
First drive the trims were all negative but just a few %. Nice.
Now I’m doing WOT tuning with the wideband.
What I notice, and have noticed on my corvette, is a flat fuel line in second or third gear, is lean in low gear. Using the same MAF cells. This LS3 is doing the same.
It bugs me.