Air/Fuel Ratio Question - Tuning Forum

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Air/Fuel Ratio Question
Wednesday, August 16, 2006 12:58 PM
I was just wondering about my air/fuel tuning. I have a Tec 3 to begin with. It says the optimal is 14.36, I think, in the air/fuel ration it gives. All of my numbers, programmed from the guy I paid to do it, is all in the 10-11 range. In the description it says that is very rich, which is how it has been running. Is it ok to adjust all of the ranges to the 14.36, not 100% sure about this number but I know it is 14 something, number since that is what it should be or is there like a place where it needs to build to this number? I know the car is running way to rich so I am working on leaning it out. I put the settings I think is right and the car seems to run really good. Just figured I would run it by you guys to get an idea.

Re: Air/Fuel Ratio Question
Wednesday, August 16, 2006 1:26 PM
depends...




"At least thats what I tell people so thats all you get "



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Re: Air/Fuel Ratio Question
Wednesday, August 16, 2006 2:02 PM
More like 12-13 AFRs are better I think. 10s and 11s are bad rich.




I was happy when I heard my car ran 10s. Then I found out that was 0-60.
Re: Air/Fuel Ratio Question
Wednesday, August 16, 2006 3:04 PM
N/A or Boost?







Re: Air/Fuel Ratio Question
Wednesday, August 16, 2006 3:10 PM
10's and 11's aren't bad rich for some cars and some levels of octane. DSM owners in my area claim there cars love 10.8 on 91 octane.







Re: Air/Fuel Ratio Question
Wednesday, August 16, 2006 3:18 PM
protomec wrote:depends...


Thats actually about the best answer here...

There is no A/F ratio you should be running. By that I mean 2 things....

1. You can't run a set a/f throughout the RPM/MAP/TPS range. If you want any kind of power, you'll have to enrich it during accleration. If you want any kind of gas mileage, you'll have to lean it out during deceleration.

2. The A/F ratio that works best for your car isn't the ratio that works best for every car. Some guy in Nevada may get best power at 11.8:1, while somebody on the other side of the country may get best power with 12.5:1 (in the cells where you need to be running rich).

Now, that being said, most people tune for 14.7:1 during cruise, boosted applications tune for around 12:1 during acceleration / in-boost. Some vehicles go off-the-chart lean during decleration (20:1 or better).





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Re: Air/Fuel Ratio Question
Wednesday, August 16, 2006 6:33 PM
So then I have another question. Why does the tec 3 recommend that a/f level, it says that is the desired level?
Re: Air/Fuel Ratio Question
Wednesday, August 16, 2006 6:47 PM
protomec wrote:

"At least thats what I tell people so thats all you get "


And as for that protomec I have been here to long and everyone always doubted me so I just deleted my registry. Tired of answering the same questions.

Juice: It is runing boost and it has nitrous but it is not hooked up.
Re: Air/Fuel Ratio Question
Thursday, August 17, 2006 9:19 AM
Quote:

It says the optimal is 14.36, I think, in the air/fuel ration it gives. All of my numbers, programmed from the guy I paid to do it, is all in the 10-11 range.


Hold on, back up a little. Where are the numbers you're looking at? In the tuning software, or the WBO2? You cannot just go by the numbers in the software. The ecm can be set up with the wrong numbers and still give the correct AFR. I would recommend changing nothing unless you have a WBO2 for checking.

-->Slow
Re: Air/Fuel Ratio Question
Thursday, August 17, 2006 1:20 PM
I am looking at the air/fuel ratio in the tec 3. It has a table just for the air/fuel ratio. When I leaned certain things out in there less black smoke. Before when I got on it black smoke would pour out.

Question about the 14, from my readings, that would be perfect but if the car runs like that it will get to hot. With the turbo the fuel helps to cool the engine. Am I reading everything right on the other forums and books? So to my understanding people run richer to keep the engine cool. Just wondering if I am reading everything right.
Re: Air/Fuel Ratio Question
Thursday, August 17, 2006 3:07 PM
i don't really know anything about boost yet, but as far as the 'ideal 14.whatever' a/f ratio-normally, ideal is 14.7:1 a/f at sea level. that is stoichiometric (sp) which is supposedly where the fuel burns cleanest and you get the most out of it. now, if you're not at sea level the number can change a little to compensate for altitude. like i said, i don't really know anything about boost yet, but the reason you're probably getting that for your 'ideal' is because i think the tech 3 is the scan tool that gm uses at their dealerships so if i'm right on that then it will tell you what's optimal for efficiency and mileage, not necessarily a modified application. if anything i said was incorrect someone please correct me. i don't want to give out false information. i just try to help.




Re: Air/Fuel Ratio Question
Thursday, August 17, 2006 3:30 PM
from my experience with the TEC3, it doesnt follow whats in the oxygen sensor table. Those values are calculated based on all the values you put in the map wizard (HP, Cam profile, injector, minimum turn on time etc)

Im running a CBR600 on the TEC 3 and i've found though dyno tuning that max torque occurs with an AFR of 12.9. That table however doesnt mean much because each RPM/MAP cell needs to be tuned for fuel and spark to achieve this as your volumetric efficiency will change at different RPM based on resonance

You'll want to set a base AFR and then adjust your TPS rate of change and MAP rate of change fuel enrichments to maintain AFR during acceleration. These values are found in the fuel enrichments table.

Yes, more fuel does cool the combustion chamber but only to a certain extent. I have found no more than 50F difference by adding fuel, adding spark removes much more heat, but then knock is always an issue.

I could go on for pages about the TEC3, i've spent my entire summer tuning it with the CBR600 engine. If you need any help with it shoot me an email
dallas_blake@hotmail.com
Re: Air/Fuel Ratio Question
Thursday, August 17, 2006 3:32 PM
Oh, if you want to simply lean out your mixture you could decrease your UAP and this will have a large effect on the upper RPM values while decreaseing the POT will have a large effect on the lower RPM values.
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