I was going to suggest the drive shaft was maybe not installed correctly somehow.

The damper on the diff could be bad.

 

As you can see, that's the coil pack end of the lead in question, and to compare to one of the normal ones. Do you think that would be enough to cause issues? Certainly doesn't seem right to me?

This is the coil pack itself...



Any way to clean inside there? or do I need to look at getting a replacement coil pack too?

 

We were way ahead of you bud.

Breakdown/degradation of spark plug leads is a well-known maintenance item with these cars. That corroded end would have a lot of resistance and could be responsible for a high-RPM misfire.

 

My bad for missing that comment.

Will need to source some of that dielectric grease, not sure where sells it in the UK without ordering online.

Will update with progress when done. Thanks guys.

 

not having grease is not your issue.

 

The grease helps with assembly (helps you feel the "clicks") and keeps out water to prevent future corrosion. It does not enhance conductance.

 

Ok, cleaned up the coil pack and fit the new leads along with the grease, car feels different, much smoother and appears to rev a lot better so I'm guessing that corrosion definitely caused these issues.

As for the vibration, still there!

However, spent some time poking around the back of the engine and noticed the bracket that holds one of the pipes/cables. Sits just above the slave cylinder, and is normally fastened to one of the looms with a cable tie but normally gets cut off when a clutch change is done. I think this might be the bloody cause after all this time, I poked it about as it's hard to get at and the vibration seemed different so I think I've ACTUALLY FOUND THE CAUSE!

Will update tomorrow as it was raining and very cold so I gave up!

 

Ugh I give up.

Engine mounts seem ok, leads only seemed to make it run smoother rather than be a cause of vibration.

Wondering whether it is just the engine being broken, or breaking, in some way.

 

is the damper still on your diff?

 

This happens when in neutral and revving. So it can't be gearbox, prop or diff related?

 

did you post a video of this happening yet?

 

It is supercharged, check the mounting bolts for the bracket, check the bracket for cracks. I believe it also has an under brace, check that.

When you rev the engine, does the supercharger move relative to the engine? It should not.

Remove the belt and rev the engine through its range, does the vibration change?

 

It's not really something I can video, and the car isn't supercharged, I think that the supercharger caused the vibration to start and it's maybe worse now 8 or so months on?

 

Well, the engine vibration just... disappeared?

I did a few jobs on the car, had to put the old downpipe back on (this was on before when it was vibrating), changed a damaged wing, changed the turbo inlet piping, fitted a boost solenoid, and some bits and bats.

I can only assume that I dislodged something when I was changing the downpipe.

I'm so happy, turned the boost up and been enjoying the car since