A/F Ratios

[Feel]

The guy the does the Turbodisplay is creating a circuit to connect to the wideband Lambda sensor.

He's asked me what ratios I want to to correspond to v lean, lean, (stoich) rich, power, & v rich. as the display shows the ratio and a bar graph representing these values.

I'm lost here, and I'm looking for some help.

 

[m0rk]

K&N don't use such long words, but: http://www.knfilters.com/airfuelmonitors.htm

 

[max_torque]

AFR Lambda Comment
17.5 1.209 Very lean (getting towards lean misfire region)
16 1.106 Lean (no misfires but not maximum torque, fuel economy)
14.47 1.000 Stoich (catalyst will only work here + or - 0.5%)
12.9 0.891 LBT (lean best torque)
10.5 0.726 Excessively rich (Maybe required for component protection)


Try that as a starter!

 

[Feel]

Cheers!

Everywhere else I've read puts Stoich at 14.7:1

 

[max_torque]

Cheers!

Everywhere else I've read puts Stoich at 14.7:1

well not to get too technical, but it actually depends upon the hydrocarbon balance of the particular fuel used, we find that typically pump fuel is approx 14.47.

the ONLY reason to run at exactly stoich is for catalyst efficiency, and even then you need to cycle the fuelling around this point to achieve maximum efficiency. (cycles between an oxygen rich and a hydrocarbon rich mixture in cat, so biases catalytic conversion between NOx and THc sequentially)

 

[LCR mat]

well not to get too technical, but it actually depends upon the hydrocarbon balance of the particular fuel used, we find that typically pump fuel is approx 14.47.

the ONLY reason to run at exactly stoich is for catalyst efficiency, and even then you need to cycle the fuelling around this point to achieve maximum efficiency. (cycles between an oxygen rich and a hydrocarbon rich mixture in cat, so biases catalytic conversion between NOx and THc sequentially)

why is it my head hurts whenever you make a post???

me press peddle car go faster

 

[BenS1]

The guy the does the Turbodisplay is creating a circuit to connect to the wideband Lambda sensor.

He's asked me what ratios I want to to correspond to v lean, lean, (stoich) rich, power, & v rich. as the display shows the ratio and a bar graph representing these values.

I'm lost here, and I'm looking for some help.

Sorry, which wideband lambda sensor? The standard ones on the car are narrowband arn't they?

Ben

 

[LCR mat]

Sorry, which wideband lambda sensor? The standard ones on the car are narrowband arn't they?

Ben

its a wide band on the LCR. narrow on the biza

 

[YerMother]

What blocks do you measure on VAG-COM to calculate A/F ratio?

You then times it by 14.1 is that right?

 

[LCR mat]

http://www.seatcupra.net/forums/showthread.php?t=58801

 

[YerMother]

http://www.seatcupra.net/forums/showthread.php?t=58801

Thanks chief

 

[wild willy]

AFR Lambda Comment
17.5 1.209 Very lean (getting towards lean misfire region)
16 1.106 Lean (no misfires but not maximum torque, fuel economy)
14.47 1.000 Stoich (catalyst will only work here + or - 0.5%)
12.9 0.891 LBT (lean best torque)
10.5 0.726 Excessively rich (Maybe required for component protection)


Try that as a starter!

Shouldn't 12.9 read rich.

 

[Balf2k]

I also thought the 12.9 should read rich

 

[ibizacupra]

12.9 richer than stoich yea...

 

[max_torque]

I also thought the 12.9 should read rich

correct, 12.9 is rich of stoich, but it is also typically what we call LBT, or lean best torque, i.e. the leanest point at which the engine will produce the highest torque. typically, especially on big boost turbo's, the ignition slope is so steep that you may find you can add fuel say down to 11 to 1 ratio, get in a few more degrees ingition (cause the extra fuel has reduced the end of compression temperatures and quenched the detonation) and make the same torque. However if you have a choice between the same torque with less fuel then this is the one to run, hence we map to LBT (assuming we are not at LBT-L, which is lean best torque - limited, i.e. when another factor, such as pre-turbine or port temperature forces us to add more fuel to protect those components etc) Most engines will, at WOT (wide open throttle) run LBT up to approx 4.5k to 5k rpm, and then switch to LBT-L from there up to the red line.)

see, easy! lol

 

[bellautos]

correct, 12.9 is rich of stoich, but it is also typically what we call LBT, or lean best torque, i.e. the leanest point at which the engine will produce the highest torque. typically, especially on big boost turbo's, the ignition slope is so steep that you may find you can add fuel say down to 11 to 1 ratio, get in a few more degrees ingition (cause the extra fuel has reduced the end of compression temperatures and quenched the detonation) and make the same torque. However if you have a choice between the same torque with less fuel then this is the one to run, hence we map to LBT (assuming we are not at LBT-L, which is lean best torque - limited, i.e. when another factor, such as pre-turbine or port temperature forces us to add more fuel to protect those components etc) Most engines will, at WOT (wide open throttle) run LBT up to approx 4.5k to 5k rpm, and then switch to LBT-L from there up to the red line.)

see, easy! lol

Im glad to see someone else on the forum understands mapping and what is involved in making good performance.

 

[m0rk]

Im glad to see someone else on the forum understands mapping and what is involved in making good performance.

lol, more than you think....

 

[ibizacupra]

Im glad to see someone else on the forum understands mapping and what is involved in making good performance.

*cough* ProDrive....

 

[bellautos]

*cough* backdoor portable afr meter

 

[ibizacupra]

hehe, wideband for me and logger.