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I changed the v6 coupe's top engine mount this afternoon. Soooooo much better! But a strange problem has now come to light - the engine does NOT like running between around 900rpm and 1100rpm. Standing still it's wobbling about a lot, 5th gear at 25-30mph it feels like the car's trying to shake the life out of me!

Since fitting the mount it's started idling low too - about 600rpm instead of the 850rpm I'd expect and stabbing the accelerator from idle produces a near-stall stutter followed by a nasty noise. Throttle response seems to have gone to hell too

Any ideas?

How is the idle controlled on these Matt? Is there a similar idle air valve to the tubby?
I'm thinking either a bad vacuum hose somewhere or a bad connection

It sounds like the engines knock sensor used to be working overtime trying to give a smooth idle (raised the revs) and now you've fixed the mount it's changed something? i.e the engines not shaking around so much.

A V6 usuallly idles low at around 700 anyway.

Maybe do an ECU reset?

The V6 has an ICV just like the tubby's, donno what the state of it is, but I bet it could do with a good clean.

I tried an ECU reset - it was actually the first thing that came into my mind

It sounds like it's running on 5 cylinders now. I thought the vibrations felt like a cylinder not firing, but since caining it a bit today I realised the engine's now sounding like a VW Bora V5. It's also lost power too, but it's still knocking out about the same as a tubby. People on the coupe club reckon it's a coil gone (can't imagine new coil packs being cheap, as all 3 are in one unit!) but I'm hoping I managed to knock a HT lead off as the ES9J4 has 3 coils and one of these failing would (I hope) affect 2 cylinders, and it doesn't seem like I've lost 2... Might get some plugs and clean up the heads a bit as there's an amount of oil around there

Fingers crossed it's a cheap fix, especially as it happened after you fitted the mount!

Eek! I presume it has/had a cat Hopefuly you'll get a clue when you look at the plugs (are you hiring an Alien face-hugger to get to the rear bank?)

steve_earwig wrote:Eek! I presume it has/had a cat Hopefuly you'll get a clue when you look at the plugs (are you hiring an Alien face-hugger to get to the rear bank?)

With luck I'll be able to get a new intake manifold gasket from the stealer by the weekend. Only way to get to the rear bank

As for the cat... hmph... hope i don't burn it out or blow it up before I get this fixed!

Are there any earth leads that were disturbed when you changed the mount? i had similar thing with one of mine, the earths looked ok but it took me taking them all off and cleaning up the threads before the thing would run properly again. worth checking as it gave a cylinder down symptom.