Hi guys - great level of knowlege here - very impressed!


I hope somebody might find this scenario familiar - with my 2006 4.8iS I am now getting a harsh vibration on idling which cycles 30 seconds on, 7-8 seconds off - I can feel it through the steering and dash, and had a good listen in the parking lot today - seems to be coming from under the left bank as you would look at it from under the hood. The 'on' phase coincides with a hydraulic charging sound (hiss), the vibration gets bigger, then tapers off and dies on the 'off' phase.

The problem is worse from cold starting after at least a couple of hours; at the same time there is a very hard / late shift from 1st to 2nd gear, but not any other gear change. The oil temp seems to be nailed to 50 for the first 5-10 mins although it warms up to 90-ish after 10 mins driving.

I tried changing for a lighter grade oil, new ATF, tranny filter and gasket, had new fuel pump and filter, replaced power steering hoses (slow leak), trickle charging, each of which has improved the ride, but I have yet to nail this one. Please don't let me rationalize and trade my beautful car in for something completely boring!!