S-AFC II - Fuel Consumption
 

Hi, I've got an NA 1988 RX7, stock ECU. I'm considering the S-AFC II as the stock ECU runs very rich. If I got it tuned (could I DIY?), and leaned out so it runs optimally, would I have a noticeable decrease in fuel consumption?

thanks.

(P.S- I posted this in the SAFC area, but I don't think anyone goes on there!):)

Well let me think, if you remove fuel to lean out the car, then i would say you would probably use less fuel...

Just playing, you will get better mileage on the highway, in town i didn't see much if any. But the butt dyno noticed a difference

I wouldn't do any tuning with out a wideband O2 sensor at the very least.

yep definitely would use a wideband O2 ITSWILL.
Let me think nvrdone, yes obviously it will use less fuel, but I'd like to know if it would make a significant difference or not?
What sort of ratio's did you have?

you would have to unplug the stock O2 sensor

I tried to be around 13.5:1 at wot but obivously it veries a little.

I have mine set anywhere from -10% to -20% at low throttle. Open throttle is set to 0. I've gotten anywhere from 180 - just short of 300 mi/tank in my 91 NA. I don't have a wideband O2 yet either. I also am taking off my SAFCII + replacing it with the neo.

are you na or turbo, you could always take it to a dyno and use there wideband and have them tune it.

use a wideband and leave the stock O2 sensor in and just get another bung for the wideband put in.

If the factory O2 sensor is plugged in, the ECU will go into closed loop mode and ignore all your SAFC corrections under low throttle. Trust me, I've had an SAFC, wideband, and stock ECU.

Can't you run with the factory O2 disconnected and run the wideband all the time? It seems feasible to me. How do wideband O2 sensors hold up to prolonged use?

It depends really on placement, type and your EGTs

Most decent wideband's will have a narrowband output that you could use.

That's understandable.


arghx, did you ever run your car that way? Wideband all the time? If so do you have any pointers?

you cannot tune an SAFC for low load driving with the factory narrowband signal going to the ECU. It will ignore the correction. If you disconnect the factory narrowband then I've been told the ECU will respond to SAFC correction under low load. I never bothered with that, but others have. You could lean it out to 16:1 under low load steady state cruising, which is where I run my car with a standalone.

You could remove the factory 1 wire narrowband sensor and just have your wideband. Then if your wideband has a 0-1v narrowband emulation wire you could splice that into the ECU. This is IMO pointless. If you want a narrowband signal going to the ECU, just use the stock sensor. It saves you trouble. You don't want a wideband in the stock bung, not if you value sensor life.

The general recommendation is 36" (or as far as you can manage and still be before the cat if you have one) from the exhaust ports or turbo, because of the heat of the rotary engine.

Anybody run this with a turbo rotary? Also incubuseva how come your switching to the neo? Because it's newer or and new features?

With the R-tek ECUs out there, why do people still mess with an SAFC?

^^ more fuel correction

How much more? the SAFC adjusts every 500rpm, which would work out to 16 points. The RTEK does 14x14 for S4 and 18x14 for S5, with the same =/- 50% range.

And you don't get timing control, secondary injector control, VDI control (s5), etc.

I guess you wouldn't be able to tell people you had APEX'i parts on your car :rolleyes:

someone should've told that to Honda before they put them in all the Civic VXs

^ A civic VX does not cruise at ~1600 degrees of EGT under closed loop operation...

As for the person asking why not use the rtek they have not come out with it for s5 turbo. :(

well, i know this is odd... but my NA 88 GTU gets like 350 miles to a tank... but that's probably because my aux ports are driven closed all the time. its because the actuators were taken off before i bought the car.

I got a freakin steal on a new one. Plus it has more points to adjust.

I meant you can add more fuel in conjunction with the rtek.