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View Full Version : Safe Good A/F ratio?



midz97
03-15-2010, 11:37 PM
Just thought I'd throw this question out there as I can not seem to find any solid answers anywhere on the internet.
What A/F ratios are you guys running on your Mazdaspeeds?
I am running Stage2+SF 93 v105 +TMIC and at idle and all through acceleration I am between
13.9-14.9:1 if I let off the gas and am coasting in gear the numbers go up to about 29:1 which I assume is normal?

so what are you guys getting? where should I be?
any input is appreciated.

WeatherB
03-19-2010, 08:46 AM
I have no clue what I am talking about but doesn't that seem lean to anyone? I thought our cars were a lot richer, closer to 11:1 under hard accerlation.

joghia
03-19-2010, 10:16 AM
Those are some dangerously high ratios midz. You're higher than 13.7...boosting and WOT you would want 11s, but you're leaning like a mofo. Watch out for zoom zoom boom.

Mazda3X2
03-19-2010, 10:29 AM
Mine runs about 11:1 WOT with no tune, with Cobb SRI and turbo inlet.

Isn't 14:1 still ok even under boost? I thought the OEM tune was overly rich to be on the safe side like always. With the tune he is running, 14:1 should make better power than 11:1 as long as it was safe to do so. No? I assumed that was part of the reason for a tune.

Gizzmo_jr
03-19-2010, 10:41 AM
Going up to 29:1 when no throttle is normal. I see the same thing on my dashhawk.

Fobio
03-19-2010, 10:47 AM
"all through acceleration" does not = WOT

if you run the AP, post up some logs...I doubt your OTS map is commanding 13.x - 14.x at WOT.

mine's steady @ 11.6 - 11.7 @ WOT...my MAF is also calibrated, with LTFT's @ +1 to +4 @ part throttle.

midz97
03-19-2010, 03:16 PM
Thanks for all the input.
but I'm new at this and I seem to have confused the ratio at WOT (11.4) with the ratio at idle (14.7) so all is good. Just put the car on the dyno this morning and it confirmed that under WOT AF is good plus I think I put down some o.k. numbers.

282 WHP
287 Torque

paper112
04-10-2010, 04:16 PM
I'm looking around because I jus installed my Cobb AP and I saw my A/F go down to a 9.6 under WOT 4th gear anyone have any suggestions or how accurate is the AP on reading that. I have a 07 MS3 with a Mazdaspeed CIA full turbo back , upgraded TMIC , and turbosmart BOV . Running stage 2 map 91 oct. MS CIA and Turbo back map. I am going to monitor a diff map. but does anyone have any ideas why I could be hitting so low, also 52 degrees F here (if that matters) idles at between 14 and 15 thanks guys
:headbang

Sean80
04-10-2010, 05:07 PM
I'm looking around because I jus installed my Cobb AP and I saw my A/F go down to a 9.6 under WOT 4th gear anyone have any suggestions or how accurate is the AP on reading that. I have a 07 MS3 with a Mazdaspeed CIA full turbo back , upgraded TMIC , and turbosmart BOV . Running stage 2 map 91 oct. MS CIA and Turbo back map. I am going to monitor a diff map. but does anyone have any ideas why I could be hitting so low, also 52 degrees F here (if that matters) idles at between 14 and 15 thanks guys
:headbang

I believe 9.6 is pretty rich. When I'm WOT, I'm around 10.5 - 11.4. But I'm only running Stage 1, so I'm not sure if that changes when you go to stage 2. Do you have a turbo inlet too? I highly recommend an inlet if you don't have one.

WeatherB
04-10-2010, 06:21 PM
Wow, 9.6 is pig rich... From what I've read people try to hit mid 11s under WOT.

paper112
04-10-2010, 11:00 PM
WOW. jus hit high 8 . I plugged my bov to recirc. I'm going to try a lower octane I am running 93 .so maybe with 91 it be a little better. car runs strong as hell . no det no problems. I'm going to do logging on monday , so i'll be able to see whats going on a lil better.

MRT_MS3
04-11-2010, 07:49 AM
WOW. jus hit high 8 . I plugged my bov to recirc. I'm going to try a lower octane I am running 93 .so maybe with 91 it be a little better. car runs strong as hell . no det no problems. I'm going to do logging on monday , so i'll be able to see whats going on a lil better.

So you were running VTA and 93 Octane gas with a stage 2 map for 91 Octane? This could be one of the reason why your running rich.

I believe to run VTA with COBB AP, you gotta get tuned though I haven't seen anyone actually run VTA with the AP. I think CP-e Standback is the only tuning management that can run VTA since it cuts fuel when you let off the throttle.

Either switch to 91 Octane gas or change your OTS Map to the correct one and do some logging to be on the safe side.



Noob Question: can you seriously damage your engine by running too rich? I thought zoom zoom boom is only for people that are running way too lean....

paper112
04-11-2010, 10:13 AM
I'm sorry I actually did switch the map to stage2 93 with right mod map and plugged bov and hit high8's. but thanks for the info on VTA with AP . I can tune that BOV hard or soft so going to log and play with that once I get enough time. As far as running too rich, I don't think it's a really bad thing engine wise, but your waisting your money dumping all your fuel into the engine. But I could be wrong.
:bang

Gizzmo_jr
04-11-2010, 10:19 AM
fowl the plugs IIRC when running rich oh and your EGT's.

paper112
04-11-2010, 10:51 AM
I'm sorry I actually did switch the map to stage2 93 with right mod map and plugged bov and hit high8's. but thanks for the info on VTA with AP . I can tune that BOV hard or soft so going to log and play with that once I get enough time. As far as running too rich, I don't think it's a really bad thing engine wise, but your waisting your money dumping all your fuel into the engine. But I could be wrong.
:bang

OK. so I grabbed my brother , and I had him drive so I could watch the AP closely. When he hammered the trottle I dropped down (lowest) to a 10.9 when he shifted is when it hit low 9's high 8's which leads me to believe it could poss be from the BOV . Sicne I didn't wanna drive fast and watch my AP all I saw was the spike that it held in between the shifts. So looks like we are gettin rid of the BOV soon and try again. like I said this is only my second day with it, with about 1 hour of driving so far. Jus trying to be safe so I get no BOOM thanks guys guys for all the comments.

paper112
04-11-2010, 10:52 AM
fowl the plugs IIRC when running rich oh and your EGT's.
Ahhh yeah didn't even think of that . +2 kudos. haha

3DEE
04-11-2010, 02:10 PM
It's gotta be the VTA blow off valve. Recirculate it.

MRT_MS3
04-11-2010, 09:30 PM
yeah with the Turbosmart BOV, its gotta be tuned. Not exactly sure how but its a matter getting the hard/soft setting to work perfect. Your better off datalogging than having someone drive the car while you watch the AP. This way, you can get info on ALL parameters not just one. You can probably post it on Cobb forums and they could assist you from there. Hope everything works out for you.

paper112
04-12-2010, 04:32 PM
Ok, so heres some data logging I did , incase anyone gives a damn.. haha. I choose what I did only becuase it was the only time I had knock retarding, which I think is pretty low. So feel free to try n make heads or tails out of it, and jus wanna say thanks to all

Seconds (sec),RPM (RPM),Knock Retard (°),Mass Airflow (g/s),Throttle Position (%),Vehicle Speed (mph),Actual AFR (AFR),DI Fuel Press. (PSI),Boost (PSI),Spark Adv. (°),Wastegate Duty (%)



799.82, 4261, 0.35, 195.31, 73.32, 86.99, 12.35, 1711.39, 18.42, 0.50, 21.71
799.94, 4280, 0.35, 198.26, 73.71, 87.61, 11.76, 1615.66, 18.71, 1.50, 16.52
800.06, 4317, 0.35, 199.73, 60.84, 87.61, 11.61, 1649.02, 19.00, 2.50, 7.62
800.18, 4340, 0.35, 183.82, 28.08, 88.86, 10.88,1 649.02, 16.82, 4.00, 0.00
800.30 ,4360, 0.35, 160.31, 24.96, 88.86, 11.47, 1672.23, 14.36, 6.50, 0.00
800.42 ,4363, 0.00, 124.88, 20.67, 89.48, 13.23, 1647.57, 9.86, 9.50, 0.00

also depending how accutrate the dyno meter is on Cobb ap several runs showed
339hp
361tq . I figure it can't be to far off

Fobio
04-12-2010, 07:10 PM
I suggest you post your logs and ask questions on MSF.org ... and not just to protect your warranty, but also for the larger user test group's experience...

furthermore, it has been demostrated that you can have your AFR's in check...

just to throw it out there...will anyone be interested in having your AP car tuned for safety and driveability only, albeit at a lower cost than say safety and driveability PLUS POWER?

Fobio
04-14-2010, 09:02 PM
http://lh3.ggpht.com/_m50f7LraxWM/S8VvG1Q2lMI/AAAAAAAADKg/LI6s-6DE180/Fobio_Apr14_Log01.jpg

Snotrocket
03-25-2011, 01:08 AM
Noob Question: can you seriously damage your engine by running too rich? I thought zoom zoom boom is only for people that are running way too lean....

Carbon build up leads to hot spots.... leads to detonation.... leads to a bad day..