01-18-2018, 06:02 AM
Dave once again you have been very precise, that makes it possible to come up with the answer sooner.
What you described is what i was expecting, it actually isolates the iacv and shows that it CAN function " normally " if told the right info.
That is supported by you unplugging the eot sensor and the bike becomes rideable again with the iacv again getting the correct input, i am aware that the iacv replacement fixed johnf's bike but let's concentrate on your case for now.
1 we have now established that the issue is very repeatable, even at low temperatures.
2 we now have a second condition that makes the bike ( somewhat ) rideable again.
3 the tps reset does in fact work repeatable and the engine reset does NOT according to your test.
The difference is that the iacv cycles at engine startup and " resets " itself according to engine temperature and that means at this stage the iacv does exactly what it is told.
As far as i can tell the iacv is " told " by the ecm to maintain a setpoint that results in 1050 rpm in correct working condition with a warm engine, it seems perfectly capable to do so for now.
In addition to all this magnus reported that his old iacv was clean when he replaced his and documented it with some good pictures, so "sticking " is not on my list of options at this time.
SO....
My suggestion is to ride some more and do exactly as you have done now, with tps unplugged just to make sure it wasn't a fluke and look for any signs of the rpm's changing, you want to make sure that unplugging the tps clears the situation every time, don't do anything else because it will prolong the faultfinding as you have mentioned.
Here's what i think happens; your tps has a spot or region in it that has a poor contact, similar to a crackle in a volume control on a radio.
The voltage from the tps is connected to a so called " a to d converter" in the ecm this a/d looks at the voltage and generates a number between 0 and 255 inside the ecm and writes this into a place in memory and updates this process 1000 times a second, this updated value is used by the ecm to decide how much fuel to inject in the engine at any one time together with other sensors and uses a " map " to decide how much fuel is required.
if the tps has a bad sector it is likely that it writes too high or too low values into the memory location and this influences the position the iacv is told to go.
So if the engine expects the idle value to be a digital value of 55 because it has learned through a tps reset that this is the lowest value and reads 85, it decides the throttle is not in the idle position and "tells " the iacv to adjust a lower or higher value of 1050 rpm.
This is my speculation of how the system works, the values are examples and vary in the real world but they represent a model to explain the principle.
So thanks again, Dave, i feel i lean a bit hard on you for information but sofar you are the only one that has helped in a meticulous way to solve the problem.
There is a possible interim solution that i think could be successful without purchasing anything but i will have to think that through some more.
I feel that we are very close to a working solution but need a little more confirmation.
Hope to hear from you with some more riding and a deciding outcome on the tps disconnected.
max
What you described is what i was expecting, it actually isolates the iacv and shows that it CAN function " normally " if told the right info.
That is supported by you unplugging the eot sensor and the bike becomes rideable again with the iacv again getting the correct input, i am aware that the iacv replacement fixed johnf's bike but let's concentrate on your case for now.
1 we have now established that the issue is very repeatable, even at low temperatures.
2 we now have a second condition that makes the bike ( somewhat ) rideable again.
3 the tps reset does in fact work repeatable and the engine reset does NOT according to your test.
The difference is that the iacv cycles at engine startup and " resets " itself according to engine temperature and that means at this stage the iacv does exactly what it is told.
As far as i can tell the iacv is " told " by the ecm to maintain a setpoint that results in 1050 rpm in correct working condition with a warm engine, it seems perfectly capable to do so for now.
In addition to all this magnus reported that his old iacv was clean when he replaced his and documented it with some good pictures, so "sticking " is not on my list of options at this time.
SO....
My suggestion is to ride some more and do exactly as you have done now, with tps unplugged just to make sure it wasn't a fluke and look for any signs of the rpm's changing, you want to make sure that unplugging the tps clears the situation every time, don't do anything else because it will prolong the faultfinding as you have mentioned.
Here's what i think happens; your tps has a spot or region in it that has a poor contact, similar to a crackle in a volume control on a radio.
The voltage from the tps is connected to a so called " a to d converter" in the ecm this a/d looks at the voltage and generates a number between 0 and 255 inside the ecm and writes this into a place in memory and updates this process 1000 times a second, this updated value is used by the ecm to decide how much fuel to inject in the engine at any one time together with other sensors and uses a " map " to decide how much fuel is required.
if the tps has a bad sector it is likely that it writes too high or too low values into the memory location and this influences the position the iacv is told to go.
So if the engine expects the idle value to be a digital value of 55 because it has learned through a tps reset that this is the lowest value and reads 85, it decides the throttle is not in the idle position and "tells " the iacv to adjust a lower or higher value of 1050 rpm.
This is my speculation of how the system works, the values are examples and vary in the real world but they represent a model to explain the principle.
So thanks again, Dave, i feel i lean a bit hard on you for information but sofar you are the only one that has helped in a meticulous way to solve the problem.
There is a possible interim solution that i think could be successful without purchasing anything but i will have to think that through some more.
I feel that we are very close to a working solution but need a little more confirmation.
Hope to hear from you with some more riding and a deciding outcome on the tps disconnected.
max