'98 V70 5 Spd Base -- Possible Fix for Idle Dip

[E Showell]

As some of you know, I've had a frustrating idle dip for years. It typically surfaces at stoplights after the car is warmed to operating temperature. It occurs when in neutral (it's a manual trans.), stopped at a stoplight. The idle will dip by about 200+/- rpm and I will feel a brief shuddering vibration. The idle never drops so low that I am concerned about stalling, but there is a noticeable dip.

Several posters over the years have noted this same "problem." Clearly it is abnormal, but it doesn't affect driveability so it is more of an annoyance than anything.

Last weekend, I changed the electric part of the ignition switch -- the part behind the directional stalk on the left side of the steering column.

The idle dip seems to have disappeared as a result (I changed the part for other reasons, but the disappearance of the idle dip seems to be a happy accident).

Note the title of this post says "possible" fix, so if you try it and it doesn't work, sorry.

[E Showell]

Idle dip came back a few weeks after changing the electrical portion of the ignition switch, but since I swapped the plugs after 40 k miles or so (I always use the three prong Volvo plugs), it appears to have vanished. I also think it is possible oil leaking from a torn PCV vent hose into the cam cover that was pooling on the cam cover may have found its way down to the plugs from time to time oil fouling them under operation and causing the dip.