1999 S70 RPM Fluctuation and deep vibration.

[E Showell]

Gang, I posted on another thread about idle drop. Mine seems to have been cured by replacement of the electrical component of the ignition switch following instructions posted on this site. I caution that this could be an instance of correlation but not causation.

[abscate]

E - was this the cure to the years ongoing 'idle dip' you have posted about?

Very interesting.

[E Showell]

It appears to be the case, but I think there is an insufficient data set yet to make a full evaluation. Right now, I am putting it in the category of correlation, and even perhaps causation, but subject to further verification. What I can say is that I haven't had the idle drop since I changed the electrical side of the ignition this past Saturday.

Notably, there was deep brown oxidation on only one pin of the electrical part of the ignition switch when I made the change. Because I had a new switch "in stock," I did not clean the existing one and re-use it, but the old switch -- now cleaned on all contacts -- is likely to be installed in my wife's car tonight given that her ignition switch seems to be acting up. If her car develops an idle drop as a result, we'll have our answer.