05-06-2020, 03:28 AM
By the signals seen in PopGun's recent video (thanks) I would say the pulse train when opening trhottle tries to open the valve, so my low idle issues after opening throttle are not because the IACV has been closed, just it didn't open or didn't open enough.
There is an extra variable I did not think about before. As the valve has not got a feedback the system is calculating the valve position by the number of pulses it is receiving, the more open the more air comes in, the more closed the less air is coming in. The bike hasn't got a MAF sensor, calculates the amount of air by the position of the Throttle Position sensor, the number of revs, the MAP sensor, the IAT sensor and having feedback from the oxygen sensors, as the first Fuel Injection systems. In this bike the IACV is also a variable for the calculation of amount of air, so the air pass section would be the aperture of the Throttle Body (calculated by the voltage through its sensor resistance) plus the aperture of the IACV (calculated by the number of pulses). Then; if the IACV does not respond to the pulses the system still will think the air flow has changed and will change the amount of fuel to maintain the stequiometric mixture 14:1
What happens when you open throttle and a pulse train is given to the valve if the valve does not respond? The air/fuel ratio will be out and also the idle speed. Of course the feedback from the Oxygen Sensors will change the short term fuel trim to adjust the combustion, same as if we had an air leak, but not instantly.
Then my hypothesis is that the idle speed is going down because when the IACV gets a pulse train and it does not respond the fuel ratio gets screwed and then it runs too rich or too lean, then step by step the system corrects it by changing the Short Term Fuel Trim and also actuating again on the IACV, that is why little by little the idle speed goes to normal in 3 or 4 seconds if it does not stall before.
So, further diagnosis required here with a diagnostic machine in order to monitor the Short and Long Fuel Trim when the issue is taking place. May I be wrong?
There is an extra variable I did not think about before. As the valve has not got a feedback the system is calculating the valve position by the number of pulses it is receiving, the more open the more air comes in, the more closed the less air is coming in. The bike hasn't got a MAF sensor, calculates the amount of air by the position of the Throttle Position sensor, the number of revs, the MAP sensor, the IAT sensor and having feedback from the oxygen sensors, as the first Fuel Injection systems. In this bike the IACV is also a variable for the calculation of amount of air, so the air pass section would be the aperture of the Throttle Body (calculated by the voltage through its sensor resistance) plus the aperture of the IACV (calculated by the number of pulses). Then; if the IACV does not respond to the pulses the system still will think the air flow has changed and will change the amount of fuel to maintain the stequiometric mixture 14:1
What happens when you open throttle and a pulse train is given to the valve if the valve does not respond? The air/fuel ratio will be out and also the idle speed. Of course the feedback from the Oxygen Sensors will change the short term fuel trim to adjust the combustion, same as if we had an air leak, but not instantly.
Then my hypothesis is that the idle speed is going down because when the IACV gets a pulse train and it does not respond the fuel ratio gets screwed and then it runs too rich or too lean, then step by step the system corrects it by changing the Short Term Fuel Trim and also actuating again on the IACV, that is why little by little the idle speed goes to normal in 3 or 4 seconds if it does not stall before.
So, further diagnosis required here with a diagnostic machine in order to monitor the Short and Long Fuel Trim when the issue is taking place. May I be wrong?