Well last summer i bought a 2002 Camaro SS A4 with 2,009 certified miles on it. I found it on AutoTrader and i couldn't believe that it had such low mileage so i took the 100 mile trip to n.jersey to take a look for myself. The car was in like showroom condition But i noticed it felt a little quicker than what my other stock LS1 f-bodies felt like. So i thought i was one of the luck ones and got a factory freak. Well i changed my stock lid to an SLP lid and Holley filter and i descreened my MAF. Well the car actually felt even quicker, i was alittle shock how fast it was for being stock. Well the other morning the temp. outside dropped to the low 40's and the car didn't want to idle. I had to hold the pedal down to keep it from stalling. So i thought the damn MAF might have been ready to **** the bed. Well i had my buddy scan my pcm with HPTuner and we found out it was SD tuned. All the MAF codes were switched off, and when the car warmed up and it idled great after it got warmed up. So i tried something and unplugged the MAF and the idle didn't move 100 rpm..lol. So i had it retuned back to stock and now the MAF codes are all back on the the VE table was back to stock.
Well i'm glad i'm back to stock, BUT i noticed the car lost a little of it's pep. By no means is it slow but its just not as peppy at part throttle. But i realized that even a bone stock LS1 SD tuning definately makes more power
I can only imagine what SD tuning must feel in a FI setup or even a good head/cam combo...I'm a believer now..haha...I'm impressed and HPT is some killer tuning software as well, but i'm sure EFILive is just the same. I just wanted to share my first experience with SD. It's no joke

 

A properly tuned close loop car with the MAF on will run the same. The VE tables are used, just like in open loop speed density, at the lower RPM range. The MAF takes primary control at about 4000 rpms and uses the VE table for a look up reference. Descreening the MAF actually did nothing and if it did anything the MAF will need to be retuned. If you don't have to retune after a mod it probably didn't make any horsepower.

 

Bingo

 

That is true for peak power, but SD is *much* more responsive to throttle...

 

Frost, I know what you mean and youhave tuned a ton more than I ever will.

I am not trying to start a debate, just curious.

What if you set your steady state MAP and RPM's higher so the MAF wouldn't be the primary reference until higher in the RPM band. On mine, the stock RPM is at 2400 rpm's (99 OS). If this was raised to 4000 rpms to match where the VE to MAF transition actually occurs would that take the difference out of the equation? You would have to tune the VE correctly but you should anyways. Just curious.

 

Even with the crossover to total MAF by 4K, there is still blending tapering down as the the RPMs get lower. I don't want you or anyone else to just take my word (or anyone else's) as gospel; try it out when you get some free time and see for yourself. SD is just 'snappier' than MAF fueling. Table lookup happens much faster than awaiting a wire to transition in temperature.

 

I agree with Frost 100% here. If your not seeing substantial improvements in throttle response your not doing it right. SD tuning is more popular in Australia than MAF based tuning. We've been doing it for years and are quite good at it. If there were no benefits to it, no one would bother. The gains at WOT are there too. And once again if you can't see them your not doing it right.

 

I wish I went sd when i first bought this sorry *** turbo system. but now im sd and love it!

 

I need to get the maf out of my car one of these days... if the car will go 9.5 @ 142 with the stock screened maf in the picture I'd be very curious what it would do with it gonzo.

 

Well heres an update...now that my buddy flashed in a stock '02 A4 camaro file we
adjusted a few things like shift firmness and pulled out tq management and added alittle
bit of timing...i'm only running a max of 27* and the car runs really good. I jumped on it today after the pcm got some miles on it and it smoke the F1's with ease. I still like the idea of having my MAF operational to make instant changes for weather conditions.

 

SD uses the IAT and MAP, and closed loop operation will ensure stoich or close when active and outside of WOT, so I'm not entirely sure where this idea comes from. I am not picking at you, I just see it said from time to time...

 

yes it is and SD all the way for me!

 

The only thing I notice is when its cold out side my afr tends to be alittle lean at cruise around 13.8 14 under wot its still 10.3-8 Pulls way harder too.

 

I think a BIG part of it is the quicker reaction with spark advance as well...ever driven an LT1? They reference spark entirely to the MAP sensor, even when the MAF is used for fueling. LT1's have EXCELLENT throttle response.

I converted my Camaro over to speed density this weekend and I am enjoying it so far. I know a lot of people don't have the best luck getting speed density tuned properly...but it's really not that hard if you try to learn and understand how it works before you start trying to tune it.

Also, if you want an M6 car to really feel snappy...turn off GM's "M6 spark smoothing" in HP Tuners as well...

 

I really did like the tip in responds that the SD tuning had...I still like my MAF tuning
and if i had the time i'm sure after some tweaking the MAF tuning would feel just as good
as the SD tuning felt...but the whole reason for me starting this post was to report that my first experience with SD was a positive one.

Quote from Frost:
"SD uses the IAT and MAP, and closed loop operation will ensure stoich or close when active and outside of WOT, so I'm not entirely sure where this idea comes from. I am not picking at you, I just see it said from time to time..."

Well the idea that the pcm can think on the fly with a MAF for more precise tuning or why would GM even bother adding the MAF. I just know when i added a lid and Holley hi-flow filter and with the air temps dropping to 42* the car wouldn't start, if the the MAF tuning was there the car would have started just fine...but since i still have the SD file stored on the harddrive i might see if i can adjust the VE table or whatever else i need to touch so no matter how cold it gets the car will start, or not i'll give it some thought first.

 

Not to start a debate, but I do prefer the MAF tune over a SD tune. I just can't reason how a tune that is done once at a certain altimeter/barometric pressure, temperature, relative humidity, and having it permanently set at that point will do as well as a MAF tune that changes as all the variables change.

Bryan Herter from PCM's for less lives by this idea as well, and won't even do SD tunes.

On the plus side, SD is great when the MAF is maxed out on the MAF tune (although that can be dealt with also).

 

^^I know what you mean, and i know Bryan Herter personally and he's a very
good LSx tuner and LT1 cars as well. But i know he preferrs MAF tuning...the thing i like
about the MAF tuning is it can adjust itself for weather changes without having to reflash
the pcm's when the seasons change. And you are right, even when a MAF is maxxed out like on a blower car, good tuners and good tuning software can deal with that issue.
But atleast i got a chance to drive my car for awhile with SD tuning, and i didn't mind it
until my car wouldn't start...lol. Then i minded, but i'm sure that could have been tuned out. But i always ran MAF tuning in my other cars and still went pretty quick n/a and on nitrous.

 

with a correctly dialed in SD tune it will not very in changing weather conditions,

im actually trying to think if i have actually done a MAF tune and i dont think i have... everything is SD

 

Thats the whole point. SD tune is the same all the time, even though the weather conditions change.

 

no they are not...
they still use all the sensors on the engine to make changes to the tune depending on temp, pressure etc etc..

a well setup SD tune has ZERO draw backs over a maf tune, most of the problems with SD tunes is the people on the keyboards thinking they know how to do them...