live4boost

iTrader: (2)

what voltage should my air fuel be at wot and idle? Also is there any dangers in tapping your air fuel gauge right off of the 02 sensor, or should it be done close to the ecu? I think I remember the ideal voltage reading was around .87 or something like that.

Thanks

live4boost

iTrader: (2)

I guess that I should make my question a little bit more clear. What voltage should my 02 sensor be sending my ecu, so that Im not running lean or rich?

Please help

mazdaspeed7

Does anybody have the a/f ratio compared to the O2 sensor voltage? I am interested in this too.

BTW, my car always runs at about .75V under acceleration.

Bambam7

The idle voltage varies greatly, whether your air pump is hooked up or not.
.870 is optimum for PISTON engines at WOT....
Group wisdom seems to say that rotaries run best at over .9

At closed loop (light throttle/criuse) it should bounce from .3 to .5 or so.

I would like also to know what is the BEST POWER voltage reading.. I've got an AFC to tune now!!

There is a page on autometer.com, under tech or something that gives a terrific A/F gauge commentary.

Bambam7

Mazdaspeed7- You can definately gain some power by enrichening the fuel a bit!!
Can anyone else give their votes as to what the best power mixture is?
Mine fluctuate from .92, down to about .8 and keeps dropping the longer I'm on the throttle!! That is fixed with the TII injectors and fuel pump... I have to tune the AFC though.
Here is a chart that shows voltage/mixtue ratio, but the "power recomandations" are for piston engines. I wouldn't really go by them
METER READING@FULL THROTTLE AIR/FUEL RATIO
.000 17.0:1
.100 17.0:1
.200 16.0:1
.300 15.5:1
.400 15.0:1
.500 14.7:1
.600 Dangerously Lean 14.6:1
.700 Getting lean 14.5:1
.800 Max power(Lean) N/A 14.2:1
.875 Max Power N/A 13.5:1
.900 Max Power (Rich) (NOS,Turbo)13.2:1
1.000 Very Rich 12.5:1

mazdaspeed7

You might want to reconsider. I just put the n/a fuel pump and seconondaries back on my car, and it has more power than ever before. With the TII pump and secondaries, I was usually getting .86V, which is TOO RICH for a n/a. N/a's make the most power slightly richer than stoich, while turbos are generally tuned for 12-12.5 a/f ratio. Turbos are tuned safe, which is ont he rich side, so they dont pop. N/a's simply dont pop from detonation unless youre running NOS. You want the most power from a n/a, run slightly richer than stoich.

Edit: I just saw you edited yours. I would say .75-.8V makes the most power on a n/a rotary. My car WAS running too rich at .86V, and I believe that was the cause of my redline hesitation. The hesitation disappeared when I out the stock fuel system back on, which put me from .86V to .75V, and my car has more power than ever before, even without the Hi-6 now.

live4boost

iTrader: (2)

I have a TII if no one knew. I just got back my safc and need some tunning. So under full boost I suppose I want .9? that seems pretty rich but I guess its better safe than sorry. on the lower rpms when Im not under boost should I tune it like a na, for instance .80 or around there? I know my car runs too rich at idle and low rpms, so what should I set it to?

Also were did you guys run your voltage input wire from your safc? I just have mine right to the 02 sensor. Is it safe?

mazdaspeed7

I added a test connecter to my harness, and the O2 sensor was one of the leads I added. But it should be fine, as long as it doesnt touch something that could melt the wire. That sounds pretty good for your tuning, .9 under boost, .8 off boost. Maybe .95 under boost if you are runnign more than 10 PSI of boost, just to be safe. Most TII's I know are tuned to 12.0-12.5 under boost if theyre running more than 10 PSI. Its pretty rich, but pretty safe too.

Scott 89t2

you can't tune a car at WOT with a standard o2... and no way you can do it using general numbers. the exact same voltage on 2 different cars could mean lean on one and rich on the other... if you are tuning your car you really need a wide band 02.

HAILERS

This link might help if you look under FAQ/TIPS and look for oxygen sensor http://autometer.com/hp/index.html but that said, from what I have read about o2 sensors reading different voltages at different temperatures, well I have serious doubts about any accuracy at wide open throttle. The general consensus seems to be that you have to have a wide band 02 sensor. They cost a bit of money though. There is a DIY site in Australia, where you can buy the circuit board and the hardware and make it yourself. About 135.00 bucks USA.EDIT: THIS SITE:http://www.techedge.com.au/vehicle/wbo2/default.htm

OPEC

I have tried to tune my car before with just the SAFC and the voltage reading, it doesn't work you can get it somewhat in the vicinity, but it is going to vary greatly by car. The only way to go is a real wideband O2 sensor. I finally broke down and installed the FJO bideband in my car, and have the monitor sitting on my steering column, so i can see what the car is doing at all times. This has helpded me imensly tune the car with the SAFC.. a real wideband is the only way to go.

HAILERS

OPEC......Was the cost around 750-800 or is there more money involved?????? Serious inquiry.Includes the sensor also, right??

OPEC

yeah it was about 800, the only additional money that i had to spend was getting a bung welded onto my DP. you get everything you need to install the unit, and it is fairly straight forward, the hardest part was getting the huge haltech style connector through the firewall.

HAILERS

Whoa! Thank you OPEC. You made my day. The part about the bung answered an unasked question I had. By the way, lets say I wanted to keep my original ECU, which needs a low voltage 02 sensor, then I would need that second bung for the new sensor also, right? The FJO's output couldn't be used with the original Ecu, could it? Is your new bung about the same distance as the original bung??
Here's some more opinions on 02 sensors if someone is interested: https://www.rx7club.com/forum/showth...threadid=46830

OPEC

The wideband that I have is strickly for tuning purposes, it is NO way ties into the stock ecu in any fashion. You still have to have the stock O2 sensor for fuel purposes. This unit just gives you a much more accurate indication of what the AF ratios are. The only thing that i had to connect to the cars original wiring, was a power and ground. I have 3 things welded into my DP, the stock O2 sensor, the FJO sensor, and my EGT probe. I have been extremely happy with this unit, it is very fast to show changes in throttle response, and I can not tell you how reasurring it is to now exactly what your AF ratio is everytime that you are underboost. That alone was worth the money.

OPEC

here is a link so you can see how i have mine mounted on the inside. if you like i can take some pics today of the control unit mounted under the hood. Wideband

HAILERS

Thanks OPEC! You answered all my questions. I've got the DIY on order http://www.techedge.com.au/vehicle/wbo2/default.htm and when and if I screw the pooch on that, I'll have a go at FJO. Seems like the o2 that comes with the car is just good for that small range of stoich around .4v and loses its accuracy above and below that figure. Bookmarked you pics. Oh, I see Sparco seats. How do you rate yours from one to ten?? Really off the subject now. I need seats.

HAILERS

More fuel for the fire. I stole this off the tech site: http://www.autospeed.com/A_0618/page1.html
More stolen material:http://www.scuderiaciriani.com/rx7/AF_meter.html

live4boost

iTrader: (2)

great info guys. I really appreciate the help. I just want to tune my car myself for the time being. I am just going to get the air fuel as close as possible with the stock 02. I am only going to run 6-7 psi of boost for now, since it is winter and crappy weather. When The next race season starts, I will run higher boost, and have to look into the wide band tune.

I like the links hailers, but Im thinking that the best way to tune my car is on the dyno. Im guessing that even the Halmeter with the different 02 sensor is not very accurate. Then Ive also heard the dyno isn't completely accurate either, because there isn't an actual load on the car. This is all kinda frustrating.

Whats the best way to go? With out the 800 bux for the wideband. Im guessing dyno tune, then wideband tune. I will have to look around to who has wide band 02 meters around here.

Thanx again guys

mazdaspeed7

The dyno DOES put a load on the car, and is by far the best way to tune, as long as the dyno has a wide band O2. You will get a graph of HP AND a/f ratio, throughout the rpm range.

Bambam7

Hmm, no one has still given a DEFINATE answer as to what the best WOT mixture is.
I have heard from reputable sources that the rotary likes it a little leaner for power (.75v or so), but have heard from other reputable sources that it likes a lot of gas for power!! (.9v+)!!
I just don't know, I guess I'll have to find out for myself
ANyone gotten an N/A tuned with a dyno and found the best mixture??
There has to be someone!
N/A, not turbo!
Later...

live4boost

iTrader: (2)

It doesn't put a realistic load. With a turbo charged car, you will boost more when you are on the road. There is more airflow, and the friction from the road will affect the boost. I mean a wideband 02 sensor that you can get readings while driving on the road. I think the best, is the combo of both.

mazdaspeed7

Have you ever dynoed a car? From what Ive seen, most people dont have problems getting full boost on the dyno. If you are having problems, run it in 5th gear if you must, that will put much more of a load on the engine.

Scott 89t2

the dyno is fine, and is alot better then doing a 4th gear pull on the road...

you don't all have to go out and spend $800 on this unit. just find a tuner that has one. and get it tuned for $100 or so.

as for bambam, there is no # because it's not acurrate. for a wide band on a turbo you want to aim for 11.6:1 air/fuel *I think*. this is going from memory.

Bambam7

Damn... no one knows what ratio for N/A?
I can use a wideband to tune with, but having the tools is uselsess unless you know what outputs you need!!!