idlesurge
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idlesurge [2016/01/12 18:41] nickracer [Throttle-body problems] |
idlesurge [2024/03/15 11:16] (current) |
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| - | Next, investigate possible problems with the Idle Speed Control (ISC) servo. Open the ECU and [[:driver01|inspect for burned ISC driver chips]]. If you find any, [[http://www.ecmtuning.com/product/servicerequest|contact ECMTuning regarding repair of the ECU]]. If there //are// burned drivers, it's quite possible that the damage was caused by ISC itself having a shorted coil. Make sure you are using the correct O-ring to seal the ISC to the throttle body. An O-ring that's too thin might not seal, too thick and it might not allow the ISC to fully close the airway. | + | Next, investigate possible problems with the Idle Speed Control (ISC) servo. Open the ECU and [[:driver01|inspect for burned ISC driver chips]]. If you find any, [[https://www.ecmtuning.com/product/servicerequest|contact ECMTuning regarding repair of the ECU]]. If there //are// burned drivers, it's quite possible that the damage was caused by ISC itself having a shorted coil. Make sure you are using the correct O-ring to seal the ISC to the throttle body. An O-ring that's too thin might not seal, too thick and it might not allow the ISC to fully close the airway. |
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| ===== Other considerations ===== | ===== Other considerations ===== | ||
| - | In order for the ECU to attempt to control idle speed at all requires that the ECU know that the throttle is closed. The ECU knows this by the state of the idle switch, so make sure that the idle switch is working by logging IdleSw in DSMLink/ECMLink or use DSMLink/ECMLink to [[http://www.ecmtuning.com/wiki/v3tpsadj|simulate the operation of the idle switch]]. Idle surge results from the ECU being forced to limit idle speed by shutting off the injectors until the engine speed drops low enough. When the ECU re-enables the injectors, the engine speed jumps back up. | + | In order for the ECU to attempt to control idle speed at all requires that the ECU know that the throttle is closed. The ECU knows this by the state of the idle switch, so make sure that the idle switch is working by logging IdleSw in DSMLink/ECMLink or use DSMLink/ECMLink to [[https://www.ecmtuning.com/wiki/v3tpsadj|simulate the operation of the idle switch]]. Idle surge results from the ECU being forced to limit idle speed by shutting off the injectors until the engine speed drops low enough. When the ECU re-enables the injectors, the engine speed jumps back up. |
| Ignition timing also has some effect on idle speed. In fact, the ECU normally varies ignition timing at idle to provide fine control over the idle speed. Make sure that base ignition timing is set properly. | Ignition timing also has some effect on idle speed. In fact, the ECU normally varies ignition timing at idle to provide fine control over the idle speed. Make sure that base ignition timing is set properly. | ||
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| Also, as your idle speed setting is increased, the intended idle speed begins to get pretty close to the rpm at which the ECU cuts fuel when the idle switch is active. A good rule of thumb is to set the Coasting FC Offset to your rpm setting minus 900. For example, if your intended idle speed is 1100 rpm, set the Coasting FC Offset to 200 to raise the fuel-cut threshold by 200 rpm. Doing so also helps ensure that the idle switch will deactivate before the engine speed increases to the coasting fuel-cut threshold during no-load throttle application. | Also, as your idle speed setting is increased, the intended idle speed begins to get pretty close to the rpm at which the ECU cuts fuel when the idle switch is active. A good rule of thumb is to set the Coasting FC Offset to your rpm setting minus 900. For example, if your intended idle speed is 1100 rpm, set the Coasting FC Offset to 200 to raise the fuel-cut threshold by 200 rpm. Doing so also helps ensure that the idle switch will deactivate before the engine speed increases to the coasting fuel-cut threshold during no-load throttle application. | ||
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idlesurge.1452642095.txt.gz ยท Last modified: 2016/01/12 18:41 by nickracer
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