A quick IVAC testing tip (possibly)

Evening,

I've got a high idle speed (which I now suspect is a leaking inlet manifold as I get a sharp sucking sound when tweaking the throttle and slow return to idle).



As recommended on this forum, I've tried resetting the IVAC stepper and also cleaned the IVAC plunger/housing but this didn't make any difference (although it was quite sooty) but I did wonder if the stepper was functioning and I've found a potentially simple way to test it (albeit not 100% certain)...



With the engine running (from coldish) I stuck my head close to the IVAC and disconnected the brown coolant sensor plug. I then heard the ticka-ticka-ticka of the stepper motor driving the plunger and a corresponding change in revs. Replacing the plug resulted in the reverse action.



So, to me, this indicates that the stepper is functioning correctly. However there is always the chance that one or more of the stepper windings are o/c and the plunger isn't moving on some of the pulses. If you hear the tick noise but there is no change in revs, this could also indicate a stuck plunger.



This is my newbie take on things so feel free to correct as needed :)

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