SAFC2 help with mpg

[JDM671]

Hi I just wanted to test out my safc2 if it will help raise my mpg. Note: Tested on a stock ka. I only have a intake and radiator. Also a stock exhaust. Ok heres the deal. I started the test from vegas to my house (which is in LA). I drove for over 230+ miles.

Heres how I tested it:
1) 85-90+ mph (nothing slower)
2) Windows and sunroof were open
3)never stopped to get gas

Results:
I saved gas like crazy!! And it is a good investment if you want to save gas. (Well for me). I just bought it because im doing a ka-t set up. But overall I saved gas.

Pics:
This is the starting point. (Vegas gas station) (196837 miles)


This is passing Baker (197033 miles)


Ok this is when Im passing Barstow (197097 miles)


Finally arrived at home LA!! (197236 miles!!!)


Tell me what you think...

[essforteen]

what was the set up on the AFC

[markyboi]

why dont you calculate it. the gas gauge could be inaccurate...

1. fill up your tank
2. reset trip meter
3. drive until almost empty or whatever you feel like
4. fill up your tank
5. calculate mpg (look at how many miles you drove since you reset the meter and divide by how much gallons you filled up the 2nd time)

[ZenkiKid]

Ive heard this could be dangerous though.. since you could be possibly leaning out your car too much?

[JDM671]

I only did -3% 1000-3500 lo settings

[bo2o]

safc is for more power.
leaning out your motor is where you power is suppose to be if your using bigger injectors that spray too much.


timing is where you would save gas.

85-90 would b wasting gas more because your reving at around 4k.

retard your timing all the way back and try driving.
on my single cam i use to do 330 on a full tank. san diago and back.
and single cams are suppose to kill more gas because of there 3 valve setup.

-3% on all the low setting isnt reallie what you were driving.

[BigVinnie]

Originally Posted by bo2o

-3% on all the low setting isnt reallie what you were driving.

The ecu also makes correction for every time you make a correction to the SAFC. The only way to truly tell if there was any significant change to the A/Fr's would be to put it on the dyno, with a data logging wide banned. This way you can see if you are losing HP. If the engine is losing power with those lean settings then you are ineffectively decreasing MPG. Since for every rotation of the engine cranking, trhe vehicle moves that many inches or mm less from inertia and momentum that was used when the engine had more power. (The law of physics).



Or just get a wide band and determine the driving situation before and after SAFC..... But that could take a few trips on a few tanks of gas...

[Def]

Originally Posted by BigVinnie

The ecu also makes correction for every time you make a correction to the SAFC. The only way to truly tell if there was any significant change to the A/Fr's would be to put it on the dyno, with a data logging wide banned. This way you can see if you are losing HP. If the engine is losing power with those lean settings then you are ineffectively decreasing MPG. Since for every rotation of the engine cranking, trhe vehicle moves that many inches or mm less from inertia and momentum that was used when the engine had more power. (The law of physics).



Or just get a wide band and determine the driving situation before and after SAFC..... But that could take a few trips on a few tanks of gas...

Misinformation yet AGAIN... You're on a roll...

Testing for BSFC on a dyno without knowing your fuel consumption is worthless.

OBD1 ECUs also aren't very aggressive with fuel trims, nor are they very good at consistently following the target AFR due to O2 sensor feedback. It does seem that reducing the MAF signal to the ECU will make you run a bit leaner.

Please stop talking about tuning/internal combustion engine theory until you get some actual experience. More than half of the stuff you post is comically incorrect.

[BigVinnie]

Originally Posted by Def

Misinformation yet AGAIN... You're on a roll...

Your mis understanding basic laymens terms. 3% lean on an SAFC will not account for a 3% reduction in injector duty cycle, especially when you have 12 NE-Points that are wide spread through out the rpm range.
It's worse with OBD2 since it is always accounting for a target A/Fr.

[Def]

Originally Posted by BigVinnie

Your mis understanding basic laymens terms. 3% lean on an SAFC will not account for a 3% reduction in injector duty cycle, especially when you have 12 NE-Points that are wide spread through out the rpm range.
It's worse with OBD2 since it is always accounting for a target A/Fr.

Of course it's not going to reduce IDC by 3%(i.e. going from 6% IDC to 3%) if that's what you're saying. It will approximately reduce the amount of fuel injected on each cycle by round about 3%. Of course, this depends on the fuel cell value and a host of other things, but 3% less airflow means about 3% less fuel.

OBD2 ECUs do not always go for a target AFR anymore than OBD1 ECUs do. They have distinct open loop and closed loop control modes.

[UNISA JECS]

Originally Posted by BigVinnie

The ecu also makes correction for every time you make a correction to the SAFC. The only way to truly tell if there was any significant change to the A/Fr's would be to put it on the dyno, with a data logging wide banned. This way you can see if you are losing HP. If the engine is losing power with those lean settings then you are ineffectively decreasing MPG. Since for every rotation of the engine cranking, trhe vehicle moves that many inches or mm less from inertia and momentum that was used when the engine had more power. (The law of physics).



Or just get a wide band and determine the driving situation before and after SAFC..... But that could take a few trips on a few tanks of gas...

The only thing the SAFC is gonna do with regaurd to changing AFR's by increase/decrease the % on SAFC would be threw manipulation of calculated TP (theoritical pulsewidth) by altering the MAF singal and since all this is being done in cruise/closed loop condition, your not gonna get far, this is controlled by the ECU.

Since all these changes are being done in the low load cruise/closed loop portion of the fuel map, the ECU is only going to react by adjusting fuel trim to hit back the target AFR in the LOAD cell.

To make any real changes, you would have to go to the extreme settings of the SAFC to over come the fuel trim correction and then your asking for trouble because you'll be accessing higher load cells when in reality your in a low load situation and the vise versa.

IMHO the SAFC is only good at getting your car to idle with larger injectors and thats all, shouldn't be used as your soul source for tuning. I myself have used a SAFC since like 2000 in turbocharged cars so im not a hater on teh SAFC but I know there is much better out there for a little more cheddar.

[Def]

Originally Posted by UNISA JECS

The only thing the SAFC is gonna do with regaurd to changing AFR's by increase/decrease the % on SAFC would be threw manipulation of calculated TP (theoritical pulsewidth) by altering the MAF singal and since all this is being done in cruise/closed loop condition, your not gonna get far, this is controlled by the ECU.

Since all these changes are being done in the low load cruise/closed loop portion of the fuel map, the ECU is only going to react by adjusting fuel trim to hit back the target AFR in the LOAD cell.

To make any real changes, you would have to go to the extreme settings of the SAFC to over come the fuel trim correction and then your asking for trouble because you'll be accessing higher load cells when in reality your in a low load situation and the vise versa.

IMHO the SAFC is only good at getting your car to idle with larger injectors and thats all, shouldn't be used as your soul source for tuning. I myself have used a SAFC since like 2000 in turbocharged cars so im not a hater on teh SAFC but I know there is much better out there for a little more cheddar.

I won't argue the tuning part of an S-AFC, as I don't like 'em when you use them on different injector/MAF combos than your ECU is calibrated for. But the closed loop fuel trim isn't as perfect as it sounds if you actually watch it on a wideband. Yes, there is a trim to get it pretty close to the target AFR(bouncing all over the place), but a change to the MAF voltage does tend to lean things out, especially since in general things are leaner on the lower load portion of the map on stock tunes.

[UNISA JECS]

Originally Posted by Def

I won't argue the tuning part of an S-AFC, as I don't like 'em when you use them on different injector/MAF combos than your ECU is calibrated for. But the closed loop fuel trim isn't as perfect as it sounds if you actually watch it on a wideband. Yes, there is a trim to get it pretty close to the target AFR(bouncing all over the place), but a change to the MAF voltage does tend to lean things out, especially since in general things are leaner on the lower load portion of the map on stock tunes.

Yea after getting my Nistune it quickly opend my eyes up and I sold the SAFCII I had with a quickness...lol....I know what you mean I have a wideband.

[sldbyuramg]

ok...whether or not you saved gas because of the SAFC2 or not is not what im here to argue because i think its a bad idea to lean it out although i have heard that the KA's run a little rich.
that was good mileage especially for coming back from vegas, there are alot of hills between Vegas and LA.

im sure not having such a lead foot will help anyone save more gas than anything else your spending money on

[bo2o]

he was going down hill mostly i think.

if your going to cali from vegas its down his mostly.

a wideband would b a good ideal. but then might as well get a knock lite too haha

id say clean your intake mani, check if all your vacumme lines are clean and no cracks, retard your enging, check compression, o2 sensor is good with a good maf sensor, and clean filter.

i use to do 280 all day locally. pumping 15 gallons. thats trully empty to full!

[sldbyuramg]

as the sequence went for picks he was headed home...baker is farther east then barstow...thus his trip was mostly uphill.

[UNISA JECS]

Generally:

Higher LOAD/TP = more fuel = less timing
Lower LOAD/TP = less fuel = more timing/actually alot more timing

[louisdaboois]

imo, LC-1 wideband, and actually monitor afr's as youre tuning the safc. i wrote a post about this a year or so ago. trimmed everything under atmos. to 14.7-15.2 and at atmos. i saw 13.5 and 12.2 under boost. just in the barrier of 'best lean torque' and provided a few extra mpg's.