Safe Air/Fuel Ratio? [Archive]

Element

01-28-2009, 11:43 AM

stoich (14.7)

its also a bit safer to run a little rich, than lean as well

Really? For some reason I thought you wanted to be below 12. I just was looking at my AFRs at WOT and I'm anywhere between 10-11.

shane02pro5

01-28-2009, 11:45 AM

Under boost you want 12.2 and under. Stock tune has you running very rich.

Element

01-28-2009, 11:47 AM

Under boost you want 12.2 and under. Stock tune has you running very rich.

Alright so I'm still safe. Thanks!

NCZ13

01-28-2009, 11:51 AM

Really? For some reason I thought you wanted to be below 12. I just was looking at my AFRs at WOT and I'm anywhere between 10-11.

he didnt say if it was under load, or just idling.

So i just gave a generic answer.

Element

01-28-2009, 11:57 AM

he didnt say if it was under load, or just idling.

So i just gave a generic answer.

Yeah my bad. Sorry about that. I meant at WOT.

Bravnik

01-29-2009, 12:15 PM

The jury is still out on what is safe on our cars due to DI. BMW runs their DI engines at 13 WOT. I have ran mine at 12.5 without issue. However, the rule of thumb is 12 under WOT as the number to shoot for.

becks

01-29-2009, 02:23 PM

Is it around 14.7 stock (without a tune)?

Bravnik

01-29-2009, 03:18 PM

Is it around 14.7 stock (without a tune)?

At Idle even with a tune it will be 14.7. At WOT I have seen stock cars in the 8's and 9's and never in the 10's. Fully bolted cars without a tune are typically in the low 10's dropping to 9's.

Tuned you should look at 12's when WOT.

H3br3w_Ham3r

01-29-2009, 03:42 PM

I'm running 9.5 at WOT on the dyno which is insanely rich. I'm hopping the intake will help that number.

bykeryder4life

01-29-2009, 06:39 PM

idle should be 14.7 and at wot you should shoot for 11.7-12.0. This motor has the potential to run leaner actually because it is DI, the bmw's run in the 13's at wot and full boost. On this car though, I would not want to see any leaner than 12.0 and no richer then 10.8 at worst

becks

01-30-2009, 09:31 AM

Sorry I've got a stupid question, what is WOT? :confused:

Cue

01-30-2009, 10:08 AM

Pedal to the metal = WOT - Wide Open Throttle..... Something our cars CAN'T DO ..lol

becks

01-30-2009, 10:21 AM

^lol....thanks

Larimer

01-30-2009, 11:08 AM

As lean as you can get without it knocking. 12 seems high but I've never messed with DI cars before.

shane02pro5

01-30-2009, 11:13 AM

I am not DI running 22psi at 12-12.2 with 0 knock but at 8.5:1 according to my J&S.

Cue

01-31-2009, 12:23 AM

As lean as you can get without it knocking. 12 seems high but I've never messed with DI cars before.

Agreed... With my CX7, 11.6-12.2 (4400rpm to 5500rpm WOT) is the highest I can get it on a knockless tune... that and 94 octane....

PCspeed3

01-31-2009, 01:15 AM

wierd, I searched for this safe AFR today and looked at this post earlier haha. Mine reads around 14.4 at idle, havent looked at WOT yet...

shane02pro5

01-31-2009, 02:38 AM

CX7 has a smaller turbo that may be working a little harder causing higher intake temps...

Cue

01-31-2009, 02:52 AM

CX7 has a smaller turbo that may be working a little harder causing higher intake temps...

Higher Boost temps (at the MAP sensor). I'm set at 17psi and can maintain constant boost temps of 100degrees..... unless I do a WOT run from 1st to 4th... then I'll get over 125.

Cue

01-31-2009, 02:54 AM

wierd, I searched for this safe AFR today and looked at this post earlier haha. Mine reads around 14.4 at idle, havent looked at WOT yet...

What are you monitoring with? Idle should read 14.8....

PCspeed3

01-31-2009, 07:16 AM

What are you monitoring with? Idle should read 14.8....

Accessport, it may have something to do with the cold temps (15° F) and my CP-E intake instead of Cobb SRI .

H3br3w_Ham3r

04-18-2009, 01:24 PM

I notice that in like 6th when I floor it the A/F ratio won't drop to where i want it but in the right gear it will. Is that normal?

UHATEIT

04-18-2009, 02:15 PM

H3br3w_Ham3r

04-18-2009, 07:05 PM

Knock retard is bad when at WOT. If your warning is going off there is something wrong.

UHATEIT

04-18-2009, 10:25 PM

Knock retard is bad when at WOT. If your warning is going off there is something wrong.

when i bought it, the dh was used so it was pre-programmed to the previus ms3 owners settings. I'm not sure what they are all set at but he told me he had it set to go off if getting over 3. I dont know anything about knock so I dont know what's good or bad

H3br3w_Ham3r

04-19-2009, 12:47 AM

when i bought it, the dh was used so it was pre-programmed to the previus ms3 owners settings. I'm not sure what they are all set at but he told me he had it set to go off if getting over 3. I dont know anything about knock so I dont know what's good or bad

From what I've heard you want as close to 0 as possible at WOT. And our cars have a bit of knock for regular driving

meicalnissyen

04-21-2009, 05:48 PM

Alright so I'm still safe. Thanks!
pig fat

lazy way to control knock

meicalnissyen

04-21-2009, 05:55 PM

As lean as you can get without it knocking. 12 seems high but I've never messed with DI cars before.
so true.

ya know, what makes interesting reading is what aviation does.

its all about egt there

you can run either side of stoich just avoid high egt

they can just lean it out til the fire goes out

lean is cooler, less fuel burnin, burns it all plus excess air flyin thru not hurtin nobody. fat is cooler, buncha gas flyin out the pipe, makes for a shorter trip and pissed off CFO's

hottest fire is at stoich, if that makes for to high an egt they LEAN til its ok

Cue

04-21-2009, 06:01 PM

when I give it gas I get a lightshow that says knock retard on it and flashed green and blue on my DH, so I can't read the damn a/f or boost/vac to tell what im at with all the flashing going on.

Does knock retard have anything to do with the a/f?

Naturally your ecu will richen the moisture once KR is detected. If you look at logs with knock, the AFR's drop the moment KR is registered...

machine0992003

04-22-2009, 07:58 PM

does anyoneknow how i can fix nasty back fires wen i shift from 1st to 3rd gears? ive had this problem since i put on a turbosmart bov, its bolt on...

Cue

04-23-2009, 01:35 AM

does anyoneknow how i can fix nasty back fires wen i shift from 1st to 3rd gears? ive had this problem since i put on a turbosmart bov, its bolt on...

recirc it....

if it is already, then tune it out...
if you don't have engine management, put a cat back on...
if your cats are on, wtf

machine0992003

04-23-2009, 01:15 PM

its recirculated already, wut do u mean when u say tune it out? no engine managment 4 me H( , ya my cats r on thats y idk wtf the issue is

shane02pro5

04-23-2009, 01:24 PM

He means tune the bov as in adjust the spring tension... but it just sound like it may be leaking?? Causing a vac leak between shifts and swinging lean.

machine0992003

04-23-2009, 03:12 PM

like moving the blue wheel to either hard or soft? or should i just get another type of bov?

SubieKiller3

04-23-2009, 11:47 PM

like moving the blue wheel to either hard or soft? or should i just get another type of bov?

no, you dont need a new bov. you just need to adjust yours. did you get it straight from SU? if you did it should have already been set where it needs to be. if you got it used the person who had it before might have adjusted it to their preference and didnt set it back when they sold it to you. i have that valve with just a cobb intake and its set 50/50 and i have just left it the way it came. no backfires at all. there is a how to somewhere in this forum on how to adjust this thing properly.