S-AFC for fuel economy?

[drifts14x]

Hey there, I have a question in the event that gas goes up to $3 per gallon. Can you use a S-AFC to turn down your fuel usage? I know people use them to boost up their performance, but could I use it to lean out my fuel mixture and use less gas? Sorry for asking such a noob question but I really wanted to know. Thanks.

[SRdave240]

I suppose you could lean out the mixture at lower RPM's Just keep it fat above 3000rpms.

I might actually try this. My plugs foul (black due to richness) but I am dynotunes so I know my a/f is ok under WOT. Maybe I foul my plugs by just driving around. Hmmmm

[masticatingcow]

Well, it's a good question, and not so noob as you might think. For myself, I'm not familiar enough with the S-AFC to know if it's possible, but I do know that leaning out your fuel mixture at high rpms will eventually destroy your engine.

It could be argued that leaning out the AF mixture just slightly would buy you a little more fuel economy without seriously endangering the engine. I think you'd get better results with a good full tune up when gas hits 2.50 and just changing your driving technique. I used to get 21mpg on my KA on crappy 87 octane, shifting at 3500 rpms, making sure to out-accelerate whatever bonehead was next to me at the light. I started shifting at 2600 rpms, and stopped flooring the gas needlessly and boosted my fuel economy to 24-25mpg on 87. This is before my next tune up, planned for May this year.

[drifts14x]

I'm glad that it isnt the most noob question ever asked, I do currently get 25mpg(mix of city and highway) shifting at 3500RPM, but accelerating slower to that speed than most. I have new plugs and a new batch of antifreeze, but what else do you suggest in this "full tune up." I figured that buying a S-AFC would be good anyways so that I could adjust my fuel for racing as well. I just want to know how or what settings to use on a S-AFC to lean out the fuel if even just a little bit.

[masticatingcow]

Some places call it different things but it's the tune up you're supposed to perform every 30,000 miles or so. Replacing the fuel filter, oil change, other fluid check/change, etc. all contribute to an engine that doesn't work as hard to achieve the same power output. Less work = less gas consumed = better mileage. My buddy's FC-3S got about 20% of its fuel economy back after one of these tune ups. (From 18 mpg to 22 mpg)

I'm interested to see how your S-AFC works out. As I've said before, I don't understand enough about it to effectively use it or give recommendations. Plus, my motor's old enough that I'd shy away from leaning its fuel out. Good luck though!

[pr240sx]

What you can do beofe tweaking your fuel maps out is to establish a good driving habit (no hard starts, over revving the engine etc)Good tune up check your oil specs (transmission and engine)tire pressurethen, when you have your engine at top peak stock level, you can then check if you need the SAFC.Does the SAFC have selectable fuel maps, you can configure one for granny driving and other one for all out performance.Even, some mods for normally aspirated engine id to maximize the engine efficiency, maybe the stock ECU fuel and timing maps are very general and very conservative just to be safe. I think that you could not go wrong using the SAFC IF you know what you are doing.

[180fan]

Cost of the AFC outweighs the benefits of better mileage in the long term. You're better off with a tune up than getting an AFC just for better mileage. Other reason, you've got to tune the AFC, just leaning it out won't do much for you since it's in small percentages that it'll adjust. I've been doing a cost comparison since I got the afc. and seriously the mileage improvement isn't much since you're not guaranteed to be running lean in all conditions. The argument that you'll get more power from the afc and thus less work needed to achieve that power is true, but you'll only see small gains if you've not done much to your engine in the first place. My recommendation, go with the tune up if you've got a near stock engine. If you plan on doing heavier upgrades like turbo or upgrading injectors, mafs, etc then it'll show more value to your roadmap to domination on the road. It is a good investment if you plan on doing upgrades as its value will increase with the more you put into your engine, but otherwise for just mileage purposes, it's cost to performance is mediocre.

[navysnail]

SRdave240- to keep your plugs from fouling, use a higher heat range.