04-25-2018, 07:51 PM
Nice going Dave, in order of appearance;
Disconnected in the running position and idling perfect for 50 miles, you stated it before but i like the sound of that!
a1; don't think it moved, which brings me to the first question; you know more about the iacv movement now, so can the shaft rotate when it is not electrically energized or is the shaft stuck or magnetically held in position ( moving but you can feel the magnetic poles hold the shaft ) when you try to rotate it?
My feeling is that the stepper motor was gradually having more difficulty in moving the shaft, reasons i can think of are;
piston not aligned with the barrel, thread binding ( i think you eliminated both of these ) pin that guides the piston too short or too long, bearings inside the stepper motor running low on lubrication, are the two stepper motors evenly strong or is one weaker? and lastly something inside the iacv motor that got in the way ( debris )
Is the piston made of plastic or metal?
can the piston unscrew completely from the shaft or is there a stop at the end and are the springs the same strength?
When you install the battery i think the iacv ( plugged in but not mounted so you can see what it is doing ) will cycle as normal, it will even do this in limp mode because it is part of the initialisation and the computer is not making a decision yet, it only sets the engine up for warm or cold start.
If you hold the piston with your fingers you can see it travel in or out ( forgot which way but it is not important for now ) .
The ecm does not know where the iacv piston is on startup, so the engineers have programmed a simple routine in the ecm by extending the travel a few steps more than required to get to one end ( either open or closed ) from there it knows the piston is at the end of travel and moves the piston in reverse----- by the amount of steps required for the operating temperature ect.----- and now the ecm knows that the piston is in the correct position to start the engine.
This always works ok on startup, every time, but something happens sometimes after some time that makes the ecm think the piston is in the right place but it dragged it's feet and is somewhere else.
I would listen to any noise that is different between old and new iacv, i am sure you have given us the clue with the different sound when it is not behaving but i cannot decode the hint for now.
If you switch on in the 30% ( warm running position in which you found it ) i think it will go to one end first and then move back some distance.
Thank you Dave.
Disconnected in the running position and idling perfect for 50 miles, you stated it before but i like the sound of that!
a1; don't think it moved, which brings me to the first question; you know more about the iacv movement now, so can the shaft rotate when it is not electrically energized or is the shaft stuck or magnetically held in position ( moving but you can feel the magnetic poles hold the shaft ) when you try to rotate it?
My feeling is that the stepper motor was gradually having more difficulty in moving the shaft, reasons i can think of are;
piston not aligned with the barrel, thread binding ( i think you eliminated both of these ) pin that guides the piston too short or too long, bearings inside the stepper motor running low on lubrication, are the two stepper motors evenly strong or is one weaker? and lastly something inside the iacv motor that got in the way ( debris )
Is the piston made of plastic or metal?
can the piston unscrew completely from the shaft or is there a stop at the end and are the springs the same strength?
When you install the battery i think the iacv ( plugged in but not mounted so you can see what it is doing ) will cycle as normal, it will even do this in limp mode because it is part of the initialisation and the computer is not making a decision yet, it only sets the engine up for warm or cold start.
If you hold the piston with your fingers you can see it travel in or out ( forgot which way but it is not important for now ) .
The ecm does not know where the iacv piston is on startup, so the engineers have programmed a simple routine in the ecm by extending the travel a few steps more than required to get to one end ( either open or closed ) from there it knows the piston is at the end of travel and moves the piston in reverse----- by the amount of steps required for the operating temperature ect.----- and now the ecm knows that the piston is in the correct position to start the engine.
This always works ok on startup, every time, but something happens sometimes after some time that makes the ecm think the piston is in the right place but it dragged it's feet and is somewhere else.
I would listen to any noise that is different between old and new iacv, i am sure you have given us the clue with the different sound when it is not behaving but i cannot decode the hint for now.
If you switch on in the 30% ( warm running position in which you found it ) i think it will go to one end first and then move back some distance.
Thank you Dave.