CB1100 Idle speed instability problem

[syncronizator_imp]

Sync, it runs on 12 v just like Speed mentioned, with a resistance of 105 ohms that means the current is 0,12 Amps or 1.5 wattts per step, not very strong.

There are 2 sets of coils inside and a multi pole permanent magnet on the rotor;



As the pulses are sent from the e.c.u. the motor "steps" with every pulse to it's next position;



You can apply some dc from your supply but the iacv will only move a small amount in one direction, energizing the other coil will move it some more, very un-interesting and disappointing to look at but it will show you the principle.

Normally the current in the two sets of coils is reversed as well but i think if you just take the 12v supply wires and pulse coil A then coil B etc. that will motivate the rotor in one direction ( video? ) and there is no danger in changing polarity in the coils,, they just move in the opposite direction.

In order to not damage the iacv use very short times to energize the coils, if the dc is applied for a long time they will overheat i think, it's very thin wire.

One possible explanation could be that the permanent magnets inside the iacv loose strength over time due to the heat which is a known phenomenon with magnets and would explain why it occurs in slow traffic with heat building up in the throttle body, just a guess and probably not the cause, it could be that the software change produces better pulses with full pulse with other than just a smaller peak as shown in Lord Popgun's nice video.

Thanks for your video, it answers a lot of questions i had previously but it still does not solve the mystery why it fails, although i found the marks inside the groove interesting, awesome of you to post this!

My conclusion:
Assuming that the ECU supplies voltage at a correct time , I wonder if IACV responds to all coil feeds and moves the piston as it should be.
Perhaps when the IACV is hot, it is not able to move the piston, and the result is that the engine RPM drops to 500 or increases to 1500.
At what step is the IACV piston then?
I forgot to mention that I did one test before IACV replacement.
Because fuel pomp is very loud i disconnected it (easy to do).
Then I turned on the ignition and listened to whether IACV works or no, (performs adaptation).
Mine was heard very clearly.


I think I will connect the IACV to the motorcycle first before testing with the power supply.
If I damage the IACV, there will be nothing to test cooperation with the motorcycle ECU.

Pawel.