My scuttle panel isn't exactly fitted tight, and my engine cover is now missing a couple of bungs..... But the car is suffering a vibration at 4,500-6,000 rpm that I can feel in the footwell and the steering wheel - both the engine mounts I can see look fine - could it be the lower engine mount? Vibration only happens when booting it..... Gearbox doesn't have any vibration in it? If it is the lower engine mount, is it best to fix asap?
I have the same problem with you. I think it's probably misfiring. Is it like 1. shaking on idle 2. It has exhaust detonation. Like this https://m.youtube.com/watch?v=VFpGZg0obkY 3. RPM don't go up to 6000 4. Whole car is shaking while push on third and so on if you have all the problems. It's defiantly misfiring. I had my plugs and coil pack changed. It does improve but problem is still. So it's about injectors. Hope it's help
FYI - this was a combination of a cracked heatsheild flapping about and a perished upper torque link in the engine bay.
