engineandecu101
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engineandecu101 [2009/02/26 12:02] twdorris |
engineandecu101 [2009/02/26 12:09] twdorris |
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| The bottom line is that you need accurate airflow readings to the ECU if you want the ECU to inject accurate fuel. | The bottom line is that you need accurate airflow readings to the ECU if you want the ECU to inject accurate fuel. | ||
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| So, you have two things now that the ECU needs to have accurate information on. First, it needs accurate airflow to calculate fuel flow requirements and second, it needs to know if you've changed anything that affects fuel flow into the engine. If you change base fuel pressure or you swap in different injectors, you have to adjust the ECU's fuel flow calculations to take this into account. | So, you have two things now that the ECU needs to have accurate information on. First, it needs accurate airflow to calculate fuel flow requirements and second, it needs to know if you've changed anything that affects fuel flow into the engine. If you change base fuel pressure or you swap in different injectors, you have to adjust the ECU's fuel flow calculations to take this into account. | ||
| + | There are two "modes" of operation for fuel control. In both cases, the ECU starts out with airflow data from the airflow sensor and calculates a 14.7:1 A/F ratio using its assumption about injector size and fuel pressure. But in "closed loop" mode, it checks to see how far off this estimate was by monitoring feedback from the O2 sensor. Closed loop mode is typically active during idle and cruise conditions. | ||
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| + | In the other mode, "open loop", it does not check these assumptions. It simply calculates fuel flow requirements and injects fuel. This is the mode the ECU operates in at wide open throttle and a few other conditions (early start up for example). | ||
| ==== Closed loop ==== | ==== Closed loop ==== | ||
engineandecu101.txt ยท Last modified: 2024/03/15 11:16 (external edit)
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