[d_mcknight]

My engine has had some rough idling issues for awhile and today I noticed a new symptom. At idle (warm or cold, but seems worse when warm), there is a distinct vibration; it is noticeable both in and out of gear, but worse when out of gear. The new symptom I noticed today is a ticking noise (sounds like arcing electrical), coming from about where the ignition coils sit (as far as I can tell). I tested the resistance of the coils against new ones off the shelf about a month ago and they measured out exactly the same.

I have already replaced plugs, wires, caps, rotors, intake manifold gaskets (though not the throttle body gasket), motor mounts. Transmission was rebuilt about 40k miles ago and flex discs, U joints were inspected, trans mount was replaced. Fuel injector cleaner has been run through the system several times and the filter changed.

I do notice a little fluctuation of my oil pressure gauge at idle (between 1 and 2 BAR), not sure if related to the idle issue. I do have the metal cam oilers and did run a chemical flush through the engine about two years ago and have been regularly changing the oil since then. Lately I have been running Castrol EDGE 0W40 at 8,000-ish mile intervals.

Any advice on what I might look at before paying for another diagnosis is much appreciated.

 

[waterdrop]

Not sure if this will be of any help but on my old Subaru SVX one of the coils was arcing on the frame and making that ticking noise you describe. I believe changing the coil would have fixed the issue however I had to get rid of the car prior to this...

 

[Richard F]

Is it worth peering under the hood after dark and trying to "see" any stray electrickery.

Yrs ago I had a misfire on a Datsun, I had the car checked (several times) to no avail. All became clear one dark and rainy night in the middle of nowhere. I had blue light dancing and flitting around the HT leads in a most entertaining fashion.

 

[Poundy]

Check the coil lead probably arcing from that. I suppose deciphering which cylinders are misfiring may advance the diagnosis.