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| The importance of beeing able to read the correct intake air temperature at the RIGHT place can't be exagerated. Most installations feature sensors that either sit in the wrong place and read the right temperature or sit in the right place but read the wrong temperature. |
| The importance of being able to read the correct intake air temperature at the RIGHT place can't be exagerated. Most installations feature sensors that either sit in the wrong place and read the right temperature or sit in the right place but read the wrong temperature. |
| One example is a sensor that sit somewhere well before the throttle body and read the right temp there, but as the fuel calculation need the mean temperature of the air when it goes through the intake the read temperature will be too low and an increased intake manifold temperature (greatly dependant on coolant temp, intake air flow and engine compartment temperature) will result in a rich condition. |
| One example is a sensor that sit somewhere well before the throttle body and read the right temp there, but as the fuel calculation need the mean temperature of the air when it goes through the intake the read temperature will be too low and an increased intake manifold temperature (greatly dependent on coolant temp, intake air flow and engine compartment temperature) will result in a rich condition. |
| An other example is that the sensor is in the correct position somewhere in the middle of the intake manifold but it get's heat soaked by the hot intake manifold at low air flows resulting in it reading the temperature of the intake manifold rather then the intake air temp. This often cause a lean condition at low engine loads. |
| An other example is that the sensor is in the correct position somewhere in the middle of the intake manifold but it gets heat soaked by the hot intake manifold at low air flows resulting in it reading the temperature of the intake manifold rather then the intake air temp. This often cause a lean condition at low engine loads. |
| Yet another condition is that the sensor is in the intake manifold, is not heatsoaked but is dimmed with fuel that vaporize on the sensor making it read a too cold temperature. |
| Yet another condition is that the sensor is in the intake manifold, is not heat soaked but is dimmed with fuel that vaporize on the sensor making it read a too cold temperature. |
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* Autronic used a "Charge Temp Estimation Table" This table is 3D Value by RPM/Load. The value is a percentage of Coolant Temp blended in with the Air Temp to calculate the estimated Charge Air Temp entering the cylinder. The Math is CLT X Table Value + AIT x Inverse of Table Value) Example 1: Table Value=50%, CLT=80, AIT=40, Charge Temp=60 degrees. (80 X 50%=40,40 X 50% =20,40+20=60) Example 2: CLT=80, AIT=40, Table Value=75%, Charge Temp=70 degrees. (80 X 75%=60,40 X 25%=10,60+10=70) Then a fixed correction is applied to the Fuel Pulse Width based on the Charge Temperature. The correction is zero at 15 deg C (Standard Air) and each 2.917 degrees C above or below that is a 1% difference in Fuel Pulse Width.(Or another way to think of this is .34% Fuel change per each 1 degree C) This table is very difficult to tune, the theory is correct but it assumes a correct air temp from the sensor, which is not always true. If the Fuel Correction could be scaled 0-100% then this method would be far more usable.(Kevin Black) |