Using S-AFC to increase gas mileage?

[EricGRIT09]

Now I think I have seen some threads on this before, but I can't seem to find them for the life of me. Maybe they weren't even here.

The question is pretty simple: Am I correct in thinking that I could lean out my low throttle points to increase my gas mileage?

In the summer, I rough tuned for 17-18psi, still running slightly rich. Now it is winter, upstate NY and freezing temperatures of course. I'm running 10psi now, nice and mild for the winter.

I was just wondering if anyone has any recommendations on some starting points for me, I would like a setup for no/little boost for my longer trips home this holiday. I know I can lean it out, but how much in the low-end? Do I really risk anything at 30% throttle and 2-3.5k in freezing temperatures with a FMIC?

 

[RallyEclipse98]

Can't tell you exact numbers without some research, but I know that yes, you can change your mileage with SAFC.

 

[Artago]

Can't tell you exact numbers without some research, but I know that yes, you can change your mileage with SAFC.

May I ask how? I'm very interested as well, although I don't have a SAFC ... yet.

 

[mini zilo]

May I ask how? I'm very interested as well, although I don't have a SAFC ... yet.

Sure you can. You would do this by leaning out your low throttle air flow adjustment.

Instead of trying to get a 14.7 on your wideband, you can lean it out to about 15.7. I have seen many people do this before.

 

[theebluecrx]

We did in a 2g gst a few years ago and it worked great.The best way to get better gas mileage is stay out of boost.I average 5 mpg more per tank when i feather the throttle.

 

[mattans]

Lean it out with the S-AFC to get better mileage. Make absolutly sure you have a wideband and possibly logging software to ensure you don't lean it out too far.

 

[Artago]

So just lean it out to get better mileage. What about emissions? By leaning it out will it help me pass emissions control? We have really tough emissions test where I live and my car has already failed twice. Would I be able to lean out the car and get it to pass? Thanks, Tom.

 

[EricGRIT09]

This is going where I thought it might go. I do have a datalogger, but no wideband. It makes sense to me at least at first glance, but I would absolutely need a wideband for my low throttle leaning out then, right?

I will be leaning it out just a tad either way, because I know for sure it is running rich.

I guess this is just another reason for me to grab a wideband .

 

[Artago]

This is going where I thought it might go. I do have a datalogger, but no wideband. It makes sense to me at least at first glance, but I would absolutely need a wideband for my low throttle leaning out then, right?

I will be leaning it out just a tad either way, because I know for sure it is running rich.

I guess this is just another reason for me to grab a wideband .

Yeah I'm getting the Zeotronix ZT-2 & ZR-2 combo soon. I can't wait.

 

[GVR4592]

So just lean it out to get better mileage. What about emissions? By leaning it out will it help me pass emissions control? We have really tough emissions test where I live and my car has already failed twice. Would I be able to lean out the car and get it to pass? Thanks, Tom.

No, you wouldn't pass emission's, NoX emissions would increase significantly an leaner than 14.7:1.

 

[Artago]

No, you wouldn't pass emission's, NoX emissions would increase significantly an leaner than 14.7:1.

Hmm ok. Thanks for the advice. I wish I knew what to do to pass emissions. Any advice? (Sorry about jacking this thread)

Tom.

 

[laserspeeddemon]

No, you wouldn't pass emission's, NoX emissions would increase significantly an leaner than 14.7:1.

Ah, but a water injection will reduce the EGT and lower the N02 emissions.

 

[GVR4592]

Ah, but a water injection will reduce the EGT and lower the N02 emissions.

And could potentially cause a misfire at low rpms, which would cause him to fail the test...again.

 

[GVR4592]

Hmm ok. Thanks for the advice. I wish I knew what to do to pass emissions. Any advice? (Sorry about jacking this thread)

Tom.

Ditch the high flow cat and get a real cat. It will make a big difference.

 

[Artago]

Ditch the high flow cat and get a real cat. It will make a big difference.

Where can I get a 3" cat?

 

[2geclipse565]

Try the wonderfull world of ebay, or call up a local exhaust shop im sure you could get one through them.

And +1 on the better gas mileage. I hooked up my safc last week and havent tuned it yet and all ready notice better gas mileage. I pulled the safc out of my last eclipse so its decently in the right area just not tuned real well.

 

[terminaltsi]

I don't know how much fuel you guys are talking about pulling out with the afc but your ecu will just bump up fuel trims to get back to 14.7 even if you do pull fuel out. (ed - read about closed loop)

Even if you max out the afc on the negative, the ecu will have fuel trims maxed to the positive and your car will run like shit because the limits of the fuel trims will be reached and you'll be lean the MOMENT you get into boost at all, like going up a hill.

I played around with this for a while and it wasn't worth it. My best mileage came from using a larger turbo. late spool=less fuel used for daily driving.