what should my air/fuel read at i know im rich at 11.5. whats optimal? im tuning with a safc II. any helpful info welcome. thanks

 

How about a bit of information first?

Turbo or NA?

Are you tuning load, idle, cruise, decel?

I assume you are using a wideband?

 

heres the skinny. its turboII im using a safcII and a aem uego. as far as i can tell the safcII tunes off the throtle posision witch is set at 20% low and 50%high then you can adjust fuel every 600rpm after 1000. can you you tune for cruise, decel, and load with a safcII? if you need more info let me know. thanks

 

11.5 under boost is pretty much where you want to be. What psi does it reach?

You can't tune much with an SAFC--just airflow correction at WOT. The TPS will read 100% with the pedal barely down. Even if you hooked up the throttle input to the pressure sensor instead of the actual TPS, all it can really do is airflow correction. It will still closed-loop under light load and pretty much ignore any correction you make.

Airflow correction just changes the signal voltage from the airflow meter to the ECU. This changes the point on the stock fuel map that the ECU is using. Imagine a spreadsheet with values in it--an SAFC will move you to a different box in the spreadsheet, but the values within that spreadsheet are fixed, unless you have an Rtek 2.0

You cannot tune acceleration/deceleration mixtures or closed loop parameters or any of that without some kind of standalone, such as a Haltech, Microtech, Megasquirt, or Power FC.

 

im just breaking the new motor in. so no boost for 2500 miles. im going to a micro tech after the break in.

 

11.5:1 is way too rich if not under boost. Under light load and cruise, you should be in the high 14s.

Under accell in vacuum, you should be seeing 12.5-13.0.

 

what should i have the lo and the high set at? im at 20% and 50% right now.

 

Because of the way the TPS is set up in the RX7, most people set low to 99% and high to 100% (or 98 and 99). Like it was said above, the TPS maxes out early in the pedal travel - in my car with the SAFC I read 100% at what feels like about 25-30% of pedal.

I don't know about it not being effective at light load though - with 10% throttle (untuned TPS) I've set the SAFC correction low enough that the engine died (NA, taking OUT fuel to pass emissions)

I'm pretty sure stoichiometric (most efficient burn) is 14.7% AFR, and I remember reading that peak HP for the TII was at 12.5% AFR - I think that's to keep it safe since you absolutely don't want to lean out under boost.

 

im not sure what was moved. the guy doing my install said he fixed the wiring on the tps and i have a readings that follow peddle movement. so at cruse it should be at 14+ under vac around 12.5 to 13 im not boosting for 2500 miles when i do its safe at 11.5.

 

ah, you must have a Series 5 then - alas, mine's a series 4 :P The TPS only follows the throttle wheel for about 3/4" before it runs out of travel. I've heard the S5 TPS are better though.

 

if it's running that rich on a stock ECU you probably have a bad O2 sensor

 

i just finished my build. everything, i mean EVERYTHING is new. i will check it out though. im starting to understand the safc II. im thinking of lowering the lo setting to 15%, and see how that works out . let me know if this is right? when i give it gas under 20% there's no corection. after 20% it kicks in, or is it gradual? also if the 02 was bad wouldn't i get some kind of light?

 

Except, according to the Mazda powertrain control manual for the RX7, the O2 sensor doesn't have anything to do with running rich or lean unless you're in Australia. :P

 

The O2 sensor only effects the mixture under closed loop, which only occurrs during periods of steady light throttle. In general it has very little effect on the mixture anyway as mileage with the sensor vs. without is hardly changed.

If you have the S-AFC connected to the full range TPS and can thus get a proper TPS reading, then you can lower the LO setting to 20-25%. You will benefit by setting up negative corrections under low throttle to pull the richness out of the stock tune. Better mileage, more power.

 

i might not be reading the wideband right. at about 2200rpms with a +5 correction, and at 16% throttle im bouncing in between 14.6 and 15. 6. if i give it a bit more i read lower on the wideband. about 12.5 to13.5 and so on. going into the 11's, even with a steady throttle it still bounces about 7 or 8 points up and down. is this how it should be?

 

yep, positive correction on the SAFC = more fuel = lower Air to Fuel Ratio (fuel is the second number, so as the fuel goes up, the ratio of air to fuel goes down)

Negative numbers on the SAFC = less fuel = higher Air to Fuel Ratio. SAFC goes from -20% to +20% (measured in percent of signal from Air Flow Meter, I believe)

So like at positive 10%, since the SAFC installs between the Air Fuel Meter and the ECU - the Air Flow Meter tells the SAFC "Hey, I'm getting X amount of air" the SAFC tells the ECU "Hey, the Air Flow Meter is getting X times 110% of air (10 percent more air than it's actually getting) and the ECUs "Cool, I'll just add 10% more fuel" The amount of air didn't REALLY go up, the SAFC just SAID it did - so the ECU dumps more fuel, and the ratio goes down - see? If you were a fixed amount rich or lean across the ENTIRE power band at WOT and cruise, you could just go get a $0.10 resistor from Radio Shack and do the same thing the SAFC is doing a lot cheaper.

 

Just some FYI about the low range tps and the throttle opening when it goes 100 percent. That angle is 18 percent. Throttle angle. Always wanted to write that down. It's out of the FSM.

 

Yeah yeah, I know, gotta get back to memorizing that thing.

 

To an extent... the ecu will ignore airflow correction under closed loop in my experience, and just continue to bounce between 14 and 15:1 on my wideband.

 

You'll notice that under light throttle before 2500rpm it's closed loop so you'll see a lot of movement in the afr. After 2500 it will be affected by the afc tune, it does not go closed loop above 2500. Feel free to correct me if I'm wrong, this is just what I've noticed on my s4. Not sure if the s5 is the same.

Brent

 

That's closed loop. The ECU is using the narrowband sensor to try and maintain the ratio at around 14.7:1. You will be doing your tuning out of closed loop. You can disconnect the stock O2 sensor to prevent the ECU from going into closed loop when you are tuning.

 

While awaiting the imminent release of the RTEK-7 2.0 for the NA S4 I've been watching my AEM UEGO trying to get some clue as to where I'll tune.

I'm noticing under decel the meter goes up through 17 and pegs for a while reading "- - -" until reaching idle where the AFR returns to normal ranges.

Is such a pronounced decel spike normal or an indication something is awry?

 

That's normal as the ECU cuts fuel during decel.