SAFC2 help with mpg

[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.

[Def]

I actually keep mine around. I find it's a good tool for a "rough sensor check." The knock function is actually moderately useful if you know what it's telling you.

[UNISA JECS]

Originally Posted by Def

I actually keep mine around. I find it's a good tool for a "rough sensor check." The knock function is actually moderately useful if you know what it's telling you.

Yea that I do miss I admit, becasue now its a chore to run the laptop and go for a run. I think i'll end up buying a Consult LCD display or Techtom mdm-100 and a knocklight.