I began tuning my streetported N/A FC the other day. I have heard a lot of rumors of where to go with it. Some say 14.7 for cruising while others say 12.8. And so on through idle and WOT. Was wondering if someone could give me some ideas of where the power and durabilty #'s should be. Thanks

 

Bump

 

i would think 12.8 would be a hell of alot better then 14.7

the lower the number the more rich your car is running....

14.7 on an AF guage is approx the middle of stoich, thats a little lean for my liking....

then again one guy said mid 13's is VERY LEAN ----- BS

i'd say mid 12's should be good, but i'm no mechanic and am going on what i understand and was told, shoot for that, if someone corrects me and points out that i'm in the wrong, thanx....

 

I've actually heard that the optimal AFR is around 16 for open loop mode. I can't hlep you with with WOT, though.. I'm still trying to figure that one out myself

edit: I guess I should note that I tune for 14.7 due to the fact that I only have a narrow-band 02 sensor for the time being.

 

do these #'S go for turbo's as well or just the n/a?

 

it shouldnt matter really....

i would prefer to run on the rich side then have the chance of hitting lean....

yeah it would be "lean" at idle and such, but at WOT you want around mid 12's i believe....

 

N/A!!!

12.4 WOT is a tad on the unsafe side for boost..

 

14's? mid to high 14's? for boost?

 

And may I make a point here?

Tuning off a narrow band is like pissing uphill.. Its just a waste of time, and I will tell you why; The Narrowband 02 sensor is pretty much designed to run at an idle and cruise mode. Your ECU disregards it in pretty much any other mode.. WOT, Decel, throttle changes, etc..

So whats the big deal? Well, when you go hauling *** around tuning for WOT on a narrow band, you introduce heat into the exhaust.. This heat is in EXCESS of the heat seen by the 02 during its normal operating cycles. And here is the kicker, neither the ECU or the 02 sensor can compensate for these variations in temperature, and they cause the 02 voltage to decline.. I believe its offscale low, which means you are reading too lean.

This may be more pronounced in my Turbo car, but I think the same applies here.

 

Man HELL NO!!

Try like 11s or som..

 

i dont know,lol never pissed with one YET!!!!! just getting a head start is all. i was thinkin that 14's was richer, must be leaner eh.?.?

 

so then what should my narrow band AF read at WOT?...

it reads 1st ornage tick left of green....

unless accessories are on....

 

Need I say more?

 

Most narrow band AF gauges (aka lightshows) read rull rich at WOT...

but that really doesn't tell you anything... like J said... it's pretty much useless

 

meh, mine done read full rich at WOT....

 

right now here is what i was thinking of shooting for. Idle- 12.2 Crusing- 12.8-13.00 WOT-12.4.

I dumped some fuel in to bring my readings down around thouse, (rember i am ported longer "durations) pulls pretty good still trying to hone in on a couple of areas, thinking about taking it to a dyno to tune it but i really want to get close to max power so i don't have to make to many pulls and blow my cash.

 

there are too many numbers just being thrown around in this thread.
as was mentioned if you really want to tune ANYTHING other than cruise, do not even consider a narrow band oxygen sensor.

for CRUISE you can run quite lean, no matter if you are turbo or not. remember you still are under vacuum during cruise even if you ARE turbo!
14.7 is a good number to aim for, but you could go even leaner. for cruise tuning it's nice to have an EGT gauge also.

as for WOT tuning, you really need to play around a bit, especially with non-turbos since there is less risk of damage from going too lean. unfortunately playing around means having a dyno.
depending on the rpm and load you may make best power around 12.0, or even in the 13.x AFR ranges...

 

A narrow band oxygen sensor is dead accurate for stoichometric only. As the exhaust temperature changes, stoic stays right where it should be. Unfortunately, both the lean and rich side vary all over the place as the temperature changes.

You can tune your engine quite well with a narrow band but only under light load. If you swap in a 3 wire heated sensor you can even tune idle reasonabley well. For light load you can shoot for 14.7.

But heavy load and WOT will be very unreliable with a narrow band sensor. For a NA car you probably won't break anything but you'll never find the best power.

The rough rule of thumb seems to be 12 - 12.5 for NA WOT and probably 11.5 - 12 for turbo.

http://www.sdsefi.com/techegt.htm
http://www.sdsefi.com/techtunesds.htm


ed

 

I read from this site I think a good explanation why narrow band sucks.


Narrow band voltage.
ex(not real numbers)
.750-850v will equal 12.4 AFR reading on a narrowband

.8 IS 12.4 on a wideband.

There are no if's or buts about it. .8v IS 12.4 AFR.

With a voltage range on a narrowband you can't get real readings.

 

Well got some goood news. We were out tuning last night and we found a happy spot. 11.3-11.5 at WOT and OMG the thing pulled like crazy!!!! Outside air temp was about 75 Degress Farenheit. Pulled so good i pulled it into a couple of mailboxes and trees. Yeah. can you say dumass, time to learn some body work. Just thought I would keep you all updated.

 

glad ya got it tuned!! suck's ya wiped out. time for the bodywork,lol!

 

so then, whats the best/safest AF to run on an S5 turbo?...

i rather it be more SAFE then anything....

 

if i was running that well on a cool night, if you have the same conditions i would say shoot a little richer. Basically find a long stright road, make a pull and then adjust it. Keeping in mind while pulling try to keep an eye on the wideband at the same time, or better yet have someone working the comp, and watching the wideband at the same time. (I would never attempt to tune off of a narrow band sensor so don't even ask :-) ) You can feel the diffrence in the seat of your pants, keep an eye on your RPM's for places that feel fat(rich) or light(lean) adjust accordingly. (sorry suck at spelling) It took me a couple of days to do it but like i said before it was a night and day diffrence. Just don't wipe yours like i did, then a whole lot of hardwork and money, and time goes down the crapper. However, i found my freind Jim Beam helps through the rough spots. Feel free to ask more I will help you the best I can, but like you I am still learning

 

Alright, for all you S-AFC guys who don't really understand tuning ajnd just want a number... here's what I go for numeric values ONLY, measured on a FJO wideband.

N/A engines:
idle: 12.8-13.6, depending on the porting type
cruise: 16.0-16.4:1, whatever prevents the engine from bucking
WOT: 13.8 at peak torque, ramping dwon to 13.6 at peak hp

Turbo engines:
idle: 12.8-13.6 depending on the porting type
cruise: 16.2-16.6:1, whatever prevents the engine from bucking
WOT: 13.5:1 in vacuum, 12.5 at peak torque, ramping down to 12.0 at peak hp

Emissions testing:
idle at 1400 rpm, idle AFR's of 18, cruising AFR's of 16.7-17.0. EGT's over 2000 degrees.
(car barely idles and surges like crazy from lean-burn misfire)


Anyone who is actually tuning their car with a EMS will know that there's much more to tuning than just aiming for one magical AFR number value.

 

^ so cruise you mean low thr and wot you mean high thr?
WOT: 13.5:1 in vacuum, 12.5 at peak torque, ramping down to 12.0 at peak hp
and what do you mean with this? i just dont understand?