2.5T (S60) Observation regarding engine vibration Topic is solved

[mrbrian200]

New knock sensor + 4 days observation... part throttle 'punchiness' is very consistent now. It was dogging a little at part throttle (sometimes) and all the time at WOT, but without another identical vehicle to compare it wasn't necessarily obvious to me.

Few days before I changed the timing belt/tensioner/pulley (at 10yr/87k) resulted in another -slight but noticeable- improvement in idle quality and general responsiveness. The OE belt stretched a bit more than I realized. Compared the old/new belts before reinstalling they would mesh together only for about 12-15 teeth. Also I noted when marking positions with a sharpie before removing the old one the error between the crank/intake sprocket was about 1/2 tooth with the old belt as per the timing marks on the engine/sprockets/cover. The notch on the crank is ridiculously difficult to see clearly (hence the marker). I used that blue kevlar belt by Gates hopefully it'll be more resilient against stretch over it's life. I was a little concerned that belt might be noisy compared to OE, but no.

[mrbrian200]

Caught/replaced a leaky injector. What felt like turbo lag at high altitude (assumed this was normal) turned out to be effects from a leaky injector that for whatever reason isn't noticeable near sea level but becomes apparent at high altitude. Can't find 93/94 octane up here that might also be a contributing factor as to why effects are pronounced/noticable. Startup crank times cut in half from consistent 1 second neighborhood to "just touch it".
As far as engine vibration is concerned I can't feel much of anything now through chassis or the wheel. World of difference from where I started out (entire car felt like one of those bed shakers at a cheap motel).
Econ looks to have ticked up, particularly during light throttle acceleration/stop and go.

[mrbrian200]

look at your fuel trim numbers!!!!!!!!! you are WAY lean + 25% on short term? look for a vacuum leak or dirty injectors that number should be close to 0 and long term should be also

This was a long time ago. As the underlying problem for this was outlined somewhere else I decided it prudent to clarify to anyone coming across this thread. In this case fuel trims were off due to a sticky throttle plate/failing throttle body (internal wear, cleaning does not resolve). Fortunately I got it sorted before any real damage was done (no burnt valves or damaged catalyst). This TB was also the single largest contributor to droney engine vibration felt through the steering wheel/chassis (idle 50-100 rpm fast and lean).