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fuelsettingshelp [2009/03/09 07:05] twdorris |
fuelsettingshelp [2011/05/01 06:32] twdorris |
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This page describes the basic usage of the Fuel tab in the ECU Config section of the ECMLink application. This page is just a dump and reformat of the same information provided in the help file with the ECMLink application. | This page describes the basic usage of the Fuel tab in the ECU Config section of the ECMLink application. This page is just a dump and reformat of the same information provided in the help file with the ECMLink application. | ||
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===== Fuel Adjustments Table ===== | ===== Fuel Adjustments Table ===== | ||
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The **Fuel Adjustments Table** allows rpm-based adjustment of the air fuel ratio relative to the ECU's stock operation. Moving a point up (or increasing the adjustment value by typing in the numeric table) makes the mixture richer; lowering it makes the mixture leaner. An adjustment of, say, -5% means multiplying the stock fuel amount by 0.95 (delivering 5% less fuel than stock). Most adjustments will be negative numbers since stock fuel delivery is a rather rich, conservative mixture. Between rpm points, the ECU interpolates between the two adjacent rpm settings. | The **Fuel Adjustments Table** allows rpm-based adjustment of the air fuel ratio relative to the ECU's stock operation. Moving a point up (or increasing the adjustment value by typing in the numeric table) makes the mixture richer; lowering it makes the mixture leaner. An adjustment of, say, -5% means multiplying the stock fuel amount by 0.95 (delivering 5% less fuel than stock). Most adjustments will be negative numbers since stock fuel delivery is a rather rich, conservative mixture. Between rpm points, the ECU interpolates between the two adjacent rpm settings. | ||
- | The adjustment described in the preceeding pargraph is fully applied only when the value for LoadFactor (essentially the same as Airflow/rev, or Boost) is above 1.6 (about 10 psi of boost). Below a LoadFactor of 0.8 (roughly atmospheric pressure) none of the adjustment is applied. Between a LoadFactor of 0.8 and 1.6, the adjustment is applied proportionally. For example, a -5% adjustment value at a LoadFactor of 1.0 results in a -1.25% adjustment actually applied: | + | The adjustment described in the preceeding pargraph is fully applied only when the value for LoadFactor (essentially the same as Airflow/rev [or Boost adjusted by VE]) is above 1.6 (about 10 psi of boost). Below a LoadFactor of 0.8 (roughly atmospheric pressure) none of the adjustment is applied. Between a LoadFactor of 0.8 and 1.6, the adjustment is applied proportionally. For example, a -5% adjustment value at a LoadFactor of 1.0 results in a -1.25% adjustment actually applied: |
Real adj = -5% * (1.0 - 0.8) / (1.6 - 0.8) = -1.25% | Real adj = -5% * (1.0 - 0.8) / (1.6 - 0.8) = -1.25% | ||
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The **Global fuel** and **Deadtime** adjustments are intended to be used mainly to compensate for injectors and fuel pressure that differ from stock. They are applied at all times. | The **Global fuel** and **Deadtime** adjustments are intended to be used mainly to compensate for injectors and fuel pressure that differ from stock. They are applied at all times. | ||
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==== Global fuel ==== | ==== Global fuel ==== | ||
- | The stock ECU assumes that the car is equipped with 450 cc/min injectors and a fuel pressure of either 37 psi (1G) or 43.5 psi (2G). As injector size is increased, the Global fuel adjustment must be made more negative. Reducing the **Global fuel** adjustment value to, say, -50% to compensate for 900 cc/min injectors cuts fuel delivery in half. | + | The stock ECU assumes that the car is equipped with 450 cc/min injectors and a fuel pressure of either 37 psi (1G) or 42.6 psi (2G). As injector size is increased, the Global fuel adjustment must be made more negative. Reducing the **Global fuel** adjustment value to, say, -50% to compensate for 900 cc/min injectors cuts fuel delivery in half. |
The needed Global fuel adjustment value may be calculated as follows: | The needed Global fuel adjustment value may be calculated as follows: | ||
FlowRateAdj1G = squareroot(BaseFuelPressure / 37) | FlowRateAdj1G = squareroot(BaseFuelPressure / 37) | ||
- | FlowRateAdj2G = squareroot(BaseFuelPressure / 43.5) | + | FlowRateAdj2G = squareroot(BaseFuelPressure / 42.6) |
+ | FlowRateAdjEVO1-3 = squareroot(BaseFuelPressure / 42.6) | ||
NewInjFlow = InjectorCCPerMin * FlowRateAdj | NewInjFlow = InjectorCCPerMin * FlowRateAdj | ||
Adj = (100 * ( 450 / NewInjFlow ) ) - 100 | Adj = (100 * ( 450 / NewInjFlow ) ) - 100 |