Hello all, I couldn't find a similar post to what I'm experiencing in my Jag, so I thought I'd make a new thread about it.

My Jag is the 1997 6.0L Daimer Double Six LWB, VIN795773. Odo meter is 48,000km

I have been suffering from engine vibration for a year. The vibration only occurs at idle range, regardless of the engine is warmed up or not. The vibration disappears when accel pedal is on and engine rev is above 1200 rpm. I thought the engine mounts might be the cause of problem as it was getting old, so I replaced the engine mounts, but the vibration problem did not improve much. Next, I thought the plugs might be suspect, so I replaced them, but it did not improve. I took a look at the condition of the removed spark plugs and they all seemed to be evenly burnt, none of them was completely black. When new spark plugs installed, I also tried changing the plug cords, but there was no change. The coolant reserve tank is not reduced, so there seems to be no coolant leak. The head gasket was not replaced since it was new.

I am not sure where I should inspect next. If any of you have any insight, I would really appreciate your advice.

Thank you very much in advance,

Kenichi

 

G’day Kenichi,

I had a slight stumble at idle with my car, a V12 like yours, and I checked the fueling and the IGN system and had no success so I eventually I took the throttle bodies off the car and accurately set the throttle butterfly gap of 0.002” and that fixed it. I also adjusted the throttle linkages correctly which won’t affect the idle quality much but ensure better running overall.

Cheers,
Jeff.