engineandecu101
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engineandecu101 [2014/11/14 08:13] twdorris [Fuel flow] |
engineandecu101 [2024/03/15 11:16] (current) |
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| So when running "open loop", the ECU does not always target 14.7:1. It targets an A/F ratio that depends on load and RPM. The picture below illustrates what this type of target table looks like. You can see that as RPM and load increase, the target A/F ratio gets richer and richer. | So when running "open loop", the ECU does not always target 14.7:1. It targets an A/F ratio that depends on load and RPM. The picture below illustrates what this type of target table looks like. You can see that as RPM and load increase, the target A/F ratio gets richer and richer. | ||
| - | {{ http://www.ecmtuning.com/images/forums/ecmlink101/2gdsmafr3d.gif }} | + | {{ https://www.ecmtuning.com/images/forums/ecmlink101/2gdsmafr3d.gif }} |
| ===== Timing (ignition advance) ===== | ===== Timing (ignition advance) ===== | ||
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| The ECU from the factory has a couple big tables it uses to look up basic ignition advance values. Those values, just like the A/F ratio values for fuel, are tweaked a bit based on operating conditions. But the bulk of ignition advance figures comes straight from the ECU's timing tables. As engine speed (RPM) increases, timing needs to increase as well. "Why" is a long story, but take it for granted that it does. As engine load (cylinder pressure) increases, timing needs to decrease. So these ignition tables are laid out with RPM on one axis and engine load on the other. The result looks something like the following. You can see that as load increases, timing decreases and as engine speed (RPM) increases, timing increases. | The ECU from the factory has a couple big tables it uses to look up basic ignition advance values. Those values, just like the A/F ratio values for fuel, are tweaked a bit based on operating conditions. But the bulk of ignition advance figures comes straight from the ECU's timing tables. As engine speed (RPM) increases, timing needs to increase as well. "Why" is a long story, but take it for granted that it does. As engine load (cylinder pressure) increases, timing needs to decrease. So these ignition tables are laid out with RPM on one axis and engine load on the other. The result looks something like the following. You can see that as load increases, timing decreases and as engine speed (RPM) increases, timing increases. | ||
| - | {{ http://www.ecmtuning.com/images/forums/ecmlink101/2gdsmtmng3d.gif }} | + | {{ https://www.ecmtuning.com/images/forums/ecmlink101/2gdsmtmng3d.gif }} |
engineandecu101.1415970816.txt.gz · Last modified: 2014/11/14 08:13 by twdorris
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