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2011-2014 Mustangs
Engine/Tuning
AEM Air/fuel gauge reading high?
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<blockquote data-quote="JUIC3D" data-source="post: 14168189" data-attributes="member: 123069"><p>Lambda > *</p><p></p><p>Let me see if I can simplify it and have it make sense.</p><p></p><p>Stoich is defined as the perfect amount of air/fuel such that the ignition will completely consume all of the fuel. It is the idea combustion that results in the complete consumption of the fuel at hand.</p><p></p><p>Stoich is ideal for part throttle and idle as it results in the highest fuel economy.</p><p></p><p>AFR is defined as an air fuel ratio. X parts of air mixed with X parts of fuel. Depending on the type of fuel, it takes different parts of air to mix with the fuel to arrive at the stoich for that fuel.</p><p></p><p>For example, the stoich in terms of AFR for PURE gasoline is 14.7:1. 14.7 parts of air for 1 part of fuel. When ignited in that ratio, the fuel will be completely consumed and result in the "perfect burn"</p><p></p><p>Stoich for E85 (85% ethanol mixed with 15% gasoline) is 9.8:1. 9.8 parts of fuel to 1 part of air.</p><p></p><p>See how ethanol stoich is lower than gasoline? That's why the stoich in terms of AFR for E10 (what's available at the pumps now) is LOWER than pure gasoline. The 10% ethanol in gas lowers the stoich for the fuel.</p><p></p><p></p><p></p><p>Now that we've covered stoich, let's talk about lambda.</p><p></p><p>Lambda is a % based measurement instead of ratio-based. 1.00 lambda = stoich. .8 lambda=80% of stoich.</p><p></p><p>Once you know the stoich of your fuel, figuring out your fueling is so much easier. Lambda simplifies it and says a lambda of 1 for a given fuel is the stoich for that fuel. Values of <1.00 are rich, values of >1.00 are lean.</p><p></p><p>Lambda of 1.00 for pure gasoline=14.7 afr</p><p>Lambda of 1.00 for E10=14.1 afr</p><p>Lambda of 1.00 for E85-9.8 afr</p><p></p><p></p><p>The stock tune commands .82 lambda at WOT which in terms of AFR would be 14.1*.82=11.56 AFR.</p><p></p><p></p><p>You can either do math calculations in your head to figure out air fuel ratio OR you can convert to "lambda thinking" and forget AFR altogether. Lambda of 1=stoich, and anything lower is rich, higher is lean.</p><p></p><p>1 lambda at part throttle and idle and .77 lambda at WOT for me. It's that simple.</p><p></p><p></p><p>Hope that helps!</p></blockquote><p></p>
[QUOTE="JUIC3D, post: 14168189, member: 123069"] Lambda > * Let me see if I can simplify it and have it make sense. Stoich is defined as the perfect amount of air/fuel such that the ignition will completely consume all of the fuel. It is the idea combustion that results in the complete consumption of the fuel at hand. Stoich is ideal for part throttle and idle as it results in the highest fuel economy. AFR is defined as an air fuel ratio. X parts of air mixed with X parts of fuel. Depending on the type of fuel, it takes different parts of air to mix with the fuel to arrive at the stoich for that fuel. For example, the stoich in terms of AFR for PURE gasoline is 14.7:1. 14.7 parts of air for 1 part of fuel. When ignited in that ratio, the fuel will be completely consumed and result in the "perfect burn" Stoich for E85 (85% ethanol mixed with 15% gasoline) is 9.8:1. 9.8 parts of fuel to 1 part of air. See how ethanol stoich is lower than gasoline? That's why the stoich in terms of AFR for E10 (what's available at the pumps now) is LOWER than pure gasoline. The 10% ethanol in gas lowers the stoich for the fuel. Now that we've covered stoich, let's talk about lambda. Lambda is a % based measurement instead of ratio-based. 1.00 lambda = stoich. .8 lambda=80% of stoich. Once you know the stoich of your fuel, figuring out your fueling is so much easier. Lambda simplifies it and says a lambda of 1 for a given fuel is the stoich for that fuel. Values of <1.00 are rich, values of >1.00 are lean. Lambda of 1.00 for pure gasoline=14.7 afr Lambda of 1.00 for E10=14.1 afr Lambda of 1.00 for E85-9.8 afr The stock tune commands .82 lambda at WOT which in terms of AFR would be 14.1*.82=11.56 AFR. You can either do math calculations in your head to figure out air fuel ratio OR you can convert to "lambda thinking" and forget AFR altogether. Lambda of 1=stoich, and anything lower is rich, higher is lean. 1 lambda at part throttle and idle and .77 lambda at WOT for me. It's that simple. Hope that helps! [/QUOTE]
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AEM Air/fuel gauge reading high?
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