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What is the optimal a/f ratio for us?

This is a discussion on What is the optimal a/f ratio for us? within the Computer & Tuning forums, part of the LSx Technical Help Section category; Hey everyone i was just curious on what the optimum a/f ratio should be for our cars......at idle and wide ...

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    Senior Member clg82's Avatar
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    What is the optimal a/f ratio for us?

    Hey everyone i was just curious on what the optimum a/f ratio should be for our cars......at idle and wide open throttle.......and anywhere inbetween.
    2000 Arctic White trans am, ws6 hood, ws6 air box, slp lid, slp smooth bellows, slp loudmouth exhaust,shift kit, rebuilt trans, LS6 intake, 3.73 gears, Shaner S3 p/p throttle body, and a tune . SFC. C6 ZO6 rims 18" in back 17" in front. Drilled and slotted rotors.

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    Military Muscle :usa: MYSCZ06's Avatar
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    depends on who you ask..google searches will give you alot of different answers and it also depends on the tuner..I know that probably not exactly the answer your looking for, wiki says this: Keeping the air-fuel mixture near the stoichometric ratio of 14.7:1 (for gasoline engines)--- other searches yielded different answers then it also depends on application F/I -nitrous etc...

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    That guy thearborbarber's Avatar
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    14.7 for lean cruise/idle/ect. and 12.8ish for power enrichment on a NA engine. I say 12.8ish because only track times or a dino will tell you exactly where you need to be.

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    Senior Member clg82's Avatar
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    Quote Originally Posted by Pewter_LS1 View Post
    depends on who you ask..google searches will give you alot of different answers and it also depends on the tuner..I know that probably not exactly the answer your looking for, wiki says this: Keeping the air-fuel mixture near the stoichometric ratio of 14.7:1 (for gasoline engines)--- other searches yielded different answers then it also depends on application F/I -nitrous etc...
    I was just curious what it would be for my 2000 Pontiac Trans Am.....I recently had my tune done and I am popping a code that says System too lean.....i am going back to have him look it over this weekend and was just wondering if it would affect my horsepower if i have him set the a/f ratio to stock.......i thought it was only for better gas miledge, any truth to this? Or is there a true horsepower gain......

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    Senior Member clg82's Avatar
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    Quote Originally Posted by thearborbarber View Post
    14.7 for lean cruise/idle/ect. and 12.8ish for power enrichment on a NA engine. I say 12.8ish because only track times or a dino will tell you exactly where you need to be.
    power enrichment? do you mean wide open throttle?

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    Military Muscle :usa: MYSCZ06's Avatar
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    what code you throwing? with your mods you will need a tune other wise Im thinking you will run rich..I could be wrong Im sure someone will correct me if I am

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    Senior Member clg82's Avatar
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    Quote Originally Posted by Pewter_LS1 View Post
    what code you throwing? with your mods you will need a tune other wise Im thinking you will run rich..I could be wrong Im sure someone will correct me if I am
    I am popping a "System too Lean" code, so I think the tuner leaned it out too much I am taking it back this weekend to have him check it that is why i was asking what my a/f should be SAFELY with a tune......

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    Military Muscle :usa: MYSCZ06's Avatar
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    here is a copy of my dyno tune N/A Cam and bolt ons 2002 TA WS6 M6 do you have a copy of your dyno? might be able to figure something out..the blue line of course is the final tune

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    That guy thearborbarber's Avatar
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    Quote Originally Posted by clg82 View Post
    power enrichment? do you mean wide open throttle?
    correct

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    TunedbyFrost.com Tuner Frost's Avatar
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    Much of this confusion comes from misunderstanding of how the system works. For the most part, you don't pick stoich or part throttle for the car, or idle, etc. It is coded into the 02 switch points. The car will always fight to achieve 14.7:1 when not in power enrinch mode or open loop. You can change the tables all you want but it will correct back to 14.7. Now, if your base tables are so screwed up that it can't get back to 14.7 no matter how much it adds (and it can add a LOT) then you get a too lean code. If you get this code, your tuner has not calibrated the underlying VE/MAF table(s) to get the car close as he should have.

    This is assuming you don't have a huge exhaust leak.

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    Senior Member clg82's Avatar
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    Quote Originally Posted by thearborbarber View Post
    correct
    What is the reason for adjusting a/f ratio......I am new to this tuning thing and I want him to put the a/f ratio back to stock but I don't want to lose horsepower by having him put back and i don't want the engine to explode by being to lean either......

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    Senior Member clg82's Avatar
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    Quote Originally Posted by Frost View Post
    Much of this confusion comes from misunderstanding of how the system works. For the most part, you don't pick stoich or part throttle for the car, or idle, etc. It is coded into the 02 switch points. The car will always fight to achieve 14.7:1 when not in power enrinch mode or open loop. You can change the tables all you want but it will correct back to 14.7. Now, if your base tables are so screwed up that it can't get back to 14.7 no matter how much it adds (and it can add a LOT) then you get a too lean code. If you get this code, your tuner has not calibrated the underlying VE/MAF table(s) to get the car close as he should have.

    This is assuming you don't have a huge exhaust leak.
    So would going back to stock a/f ratio affect my horsepower at all? What is the reason for adjusting a/f ratio on a full bolt on car....just for gas miledge?

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    Military Muscle :usa: MYSCZ06's Avatar
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    One of the reasons too tune is to optimize your mods and to bing the a/f back to a correct setting... I dont believe with your mods you can go back to a stock a/f then you wil be too rich lose HP foul plugs etc

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by clg82 View Post
    So would going back to stock a/f ratio affect my horsepower at all? What is the reason for adjusting a/f ratio on a full bolt on car....just for gas miledge?
    you are not understanding what I said here and in the PMs. Your tuner isn't picking your closed loop AFR, he just has the underlying tables so far off that the car can't get itself back to where it wants to be.

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    Senior Member clg82's Avatar
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    Quote Originally Posted by Pewter_LS1 View Post
    One of the reasons too tune is to optimize your mods and to bing the a/f back to a correct setting... I dont believe with your mods you can go back to a stock a/f then you wil be too rich lose HP foul plugs etc
    Quote Originally Posted by Frost View Post
    you are not understanding what I said here and in the PMs. Your tuner isn't picking your closed loop AFR, he just has the underlying tables so far off that the car can't get itself back to where it wants to be.
    The car ran, and runs perfectly fine! So how would returning to stock a/f ratio be bad for the car........

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by clg82 View Post
    The car ran, and runs perfectly fine! So how would returning to stock a/f ratio be bad for the car........
    you aren't scanning and tuning, how do you know it's fine? IF the underlying airflow tables are so far off that you get lean codes, you certainly get knock at tip in from transient fueling being so far off.

    You aren't "returning to your stock a/f ratio" or making any change to that, or running anything other 14.7 at idle and cruise. You don't just pick some AFR, the PCM PICKS IT (based on O2 switch voltage) and tries to maintain it. How would your tuner even do this anyway, you said yourself he wasn't using a wideband which means he can't even tune your WOT AFR, the part that we CAN pick.

    Just be aware that things are seriously jacked up if you are getting these codes and have no exhaust leaks.

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    Senior Member clg82's Avatar
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    I am going to call him in about a half an hour and then I will report back and let you know what he says.........

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    Senior Member clg82's Avatar
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    Too make a long story short, I will probably end up sending my pcm to FROST anyways to sort this mess out........but I love the way he set up the shift points and removed the torque management and raised the rev limiter but I have no idea how to request this when I send my pcm into you.........

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    TunedbyFrost.com Tuner Frost's Avatar
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    I'm not baiting to steal a customer here; I don't want anyone to misunderstand. If you think you will go with my services, I will just let others post their input to the situation.

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    Senior Member clg82's Avatar
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    Quote Originally Posted by Frost View Post
    I'm not baiting to steal a customer here; I don't want anyone to misunderstand. If you think you will go with my services, I will just let others post their input to the situation.
    no one is getting that idea, but how do I convey to you how stiff i would like my shift points, rev limiter, and torque management on the order sheet from your website...

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