i mea what the hell? the 5.0 guys with SD want to convert to MAF while LSx guys wnt SD. wtf mate? have i missed something in the translation? to me the maf is the better way to go no matter wht because it measures actual air flow and sd measure mani pressure based on atmospheric pressure. and no i dont wnt" because ford sucks, thats wwhy." keep it intelligent. i wanna knw why itd be different (besides make).

 

I'm not aware of any good pcm retuning software for the fords, so they may want to go with a maf to compensate for minor engine mods without retuning. The ls-1 guys who are interested in sd are mostly those who are making more power than the maf will handle. Maybe someone who drives the damn infernal mustangs can chime in here with a better answer.

 

I think it's mostly a matter of convenience. We disconnect the MAF so we can tune our VE tables to get our trims in line. We get them all nice and pretty, and our cars are running great. But then, if we want to hook the MAF back up without screwing our fuel trims all to hell, we have to log more data and then try to scale the MAF table so it doesn't jigger our trims. So some people at this point say "Why mess with success? Why spend all the time and effort to get the MAF to play nice when my car's running so awesome right now?"

Yes, a properly calibrated MAF is the most accurate way to measure the incoming airmass in various conditions. However, the airmass calculation used by the PCM takes into account both pressure and temperature, so a properly tuned VE table will lead to a pretty accurate airmass calculation. It's things like humidity that the PCM doesn't calculate for.

Personally, I run SD. For one, because I don't want to screw around with the MAF. And for two, because my trims don't change noticably if it's 40 degrees outside or 80. So, I see no reason to bother with it.

 

Ford computers do not have nearly the speed density setups that the GM comptuers do, the backup tables on the newer fords are just an modified alpha n setup, as most do not run a map sensor. The maf has full control of airflow, which controls fuel and timing, since timing on fords is load based, not overall airflow based vs rpm. The maf only has a lookup table for reference if the maf value's are out of range and will clip load accordingly. This is why the 2003 cobras run lean without a tune. On the ford side there are OEM maf's that will support 450-500 rwhp (90mm lightning), and OEM style maf's out there (SCT BA2400 & BA2800) that will support 600-800rwhp depending on the setup.

I personally will never take a maf off of my car, but thats my $0.02



Ryan

 

I'm just beginning to tune my car, and I'm going to keep the MAF sensor after I'm done. There are some great tuning tools in the way of some pretty nicely done Excel spreadsheets out there than can help get your MAF tables right back in line after VE tuning. There are a lot of people on this board that have been down this path with success, and are more than happy to answer questions.

 

your exactly right...but ford guys know the 87/88 fox body 5.0's with SD were the fastest...maf is great when trying to get the computer to compensate on the stock computer to different mods but you'll almost always make more power without a maf in SD. For reference I owned an 88 gt with SD

 

sd you have to make temperature based changes for temp changes. its safe for every day driving if you tune for the low end temps but it richens up at temp goes up. as long as you base all your tables from a correctly calibrated ve (all your tuning done in the same temp) only thing u have to do is multiply the table for temp changes. its a PITA but you can have seasonal tuning, summer and winter tune would work out, you have to make the changes as opposed to the maf making the changes, just have to decide how you want it really...

 

ttt guys, this is turning out well
so really it has to do with personal preference for one and two because the maf doesnt read air temp? why not move the air temp sensor to the maf housing to get at the maf wires? it seems like if u could somehow include temp into the maf's reading all would be fine. also have a choice in bigger maf's from like 90-150 or so for the huge applications like turbo, s/c, and stroker motors or a combination.

 

Even on a maf car you have a iat sensor, on the 5.0 cars it is in the upper intake. The rest have a iat sensor in the intake track. This eliminates the need to have seasonal tuned, ect. Set up the maf transfer function correctly, everything else will work fine off of that. the GM camp is so anti adjusting the maf transfer function for different airflow tracks, and all into the ve tables.

The 2001 fords moved the sensor into the maf, similar to the vette/trucks of gm.

Ryan

 

whats funny is its been this way since the 80s...

GM TPI guys like the SD.... the ford guys just like the MAF..


but then again, the GMECM guys have full access to EVERYTHING and can cheaply and easily change everything..

ford guys use a "calibrated" MAF...


diffrent systems, diffrent approches.

**points to avatar**

 

i think the maf sensor has its own temp sensor in there, as a small resistor, but i may be wrong. either way with a MAF sensor it uses the IAT to determine the flow by calculation, without the maf sensor on the car you car doesnt know how to compensate for changes in atmospheric conditions. thats the biggest difference in sd tune and maf tune, although from what i can see on my car, the maf tune can be dialed in better and give you better performance as long as you tune per current IAT

 

Nope. Here is the formula the PCM uses to back calculate for mass flow:

VE = ((mass flow * IAT / (MAP * RPM * Displacement))

As you can see, it takes into account both temperature and air density when calculating the mass flow, making it valid for different temps and altitudes. I finalized my most recent tune in 40 degree weather, with all my STFT's between +/-4. My LTFT's are disabled. I've recently relogged with the same tune in 80 degree weather, and all my STFT's are still in the same range. So, it would seem to me that the SD calc is doing a damn fine job with temp variations. That being said, our humidity here in NM doesn't really change much throughout the year. Since the mass flow calc doesn't take humidity into consideration, I see that as probably being the biggest factor that can throw off your trims in SD mode.

 

Calibrated meters became obsolete a few years ago with the availability of good ford tuning software. You will notice I put "oem" and oem style meters in my first post. The ford guys with good tuning software has as much control if not more than the gm stuff.

People have been using calibrated meters for years, so it sticks that you need to have them, In all honesty 95% of problem tuning cars are related to this type of meters.

Ryan

 

Some years have the temp sensor in the MAF, while later years have it moved to the air lid. Also, a MAF sensor does not calculate air flow, it measures it. It is simply a heated element. As air passes over it it is cooled, and the rate/amount that it is cooled is used to measure the mass of the air flowing past it. It does not use the IAT sensor to "calculate" flow, that's what the mass flow calc does.

 

wrong wrong wrong wrong wrong!

i donno where the hell this idea comes from, but i see it posted on here quite often..

if that was true, half the cars out there wouldnt run.. it wasnt until just before mandatory ODBII that alot of cars went to MAF for finer control... there are ALOT of SD based cars out there...



current IAT?? define that.

because i can tell you, sitting in my driveway, my temp might be 100* then 30 seconds later down the road its at 75*... if you've ever ridden a motorcycle you would also know about how "low spots" on the road can have air thats 10* cooler just sitting there.

no, your IAT is constantly fluctuating... you arnt tuning by it.. or for it.




i honestly havent looked at ford stuff in the last couple years... but yea, i dont like them either... id prefer to have a meter i KNOW is 100% accurate (or close too it, lol)
im not a fan of lying to the computer about sensor data... i like to tell it whats really going on, and fix the lookups.

 

What he said.

 

silverhawk, thanks for the info i wasnt sure on the calculations. i knew it was based on cooling of the resistors in there i jsut wasnt thinking about that at the time of the post. thanks for correcting me though. yes the pressure play a fairly large role you are right, but in the last calculations i used for airflow=density*area*velocity and the density calculation was done at density=pressure/gas constant* temp in degrees R the changes i put in for pressure didnt effect it a whole lot, although i coudl have done it wrong i didnt have a calculator i did it in my head.

i talked iwth my thermo professor and he said it would be ok to disreguard the humidity levels becuase that only makes up a very small % of the airflow. i agree it does throw it off and i feel like it should be accounted for but he said for these calculations it could be considered negligable without issue.


mr dude, if im wrong thats great, and i hope that i am. just as far as i knew the car didnt make changes in temp based on the IAT sensor. i havent logged in large temp changes but i have gone 40* changes and everything seems to be right in line still. i just assumed that the car didnt compensate. my friends s10 doesnt have a maf and in hot temps his fuel trims go up, but that coudl be how the s10 is. yeah i know lots and lots of car, prob 75% of the cars on the road, dont have maf sensors, i just assumed that the temp change was in the error resulting in them to change to maf sensors to take this error down. i know the IAT keeps on changing but i was saying for a majority of the tune at xx deg.

i dont have my license so i cant just go out and log in temp changes. although from what i have seen its been ok. from what i have read, i didnt think the computer could do anyhitng to the airflow on temp, i actually posted and asked if the IAT sensor was used to calculate the airflow. the temp is the biggest error so if thats emiminated then great. im just going on what i was told, but my first thought was SD would be fine becuase so many cars ran on it anyway.

i dont want you guys to get all jumpy at what i say, this is just what i have been told by a lot of people and i just got into this tuning stuff so i dont really know all the details or computers calculations. what i was saying about without a maf the car cant account for atm condition changes i was thinking about temps. like i said this is just how i saw it on my friends s10. 30* out trims were at 0 -1 and at 75* they were at -4 -5 consistnetly. in a 70* swing of temps the fuel only changes by 8.5% so its not so much taht a car wont beable to run, just run richer, so i thought cars were tuned to be safe in cold temps and just ran rich in the summer. like i said this is just what i have read and have been told, thanks for clearning some things up though, i like your answers better lol

 

like i said, this was my first thoughts, why else would they have IAT sensor in the car. you guys are the first 2 people to argue that point, when i posted about it before i was tore up by everyone saying no no no your wrong lol

 

IAT is at least used for timing

Ryan

 

Keep in mind the IAT reading is taken at the air lid and is then filtered based on coolant temp. Since the sensor isn't actaully reading the conditions of the air in the intake manifold, that could make your trims vary. I think it would be better to have the IAT sensor in the intake like the map sensor is, then you wouldn't need a filtered value. Also I have a feeling that you could tweak the coefficient to the filter and make your trims vary less with temperature, especially if you've done the tb bypass.