What's so special about 2000rpm?

[ybt1982]

Hi folks

It's been a while since I posted on here, the car has been faultless and I'm still enjoying every single mile

A strange thing has started happening though, and only at 2000rpm. No matter how much throttle or how fast I get to said rpm there is a distinct rattle/shudder type noise from behind the dash. It only happens at 200rpm, no where else and whilst it isn't changing the performace it is a bit annoying.

Any ideas?

Nick

[cookie450]

I had similar issues with my chim after I added the plenum spacer. Turned out it was one of the throttle return springs resonating on the front mesh grill.
Mine was more like a wasp stuck in the dash exactly at 2100 rpm

Not sure if the gives you any clues but hope it helps
Cheers
Steve

[ybt1982]

That's not a bad way to describe it either. Hard to fix?

[Quietlybonkers]

Throttle return springs are easy to see, just under the back edge of the bonnet - and you don't need both of them, so take one off and see if it improves...

[cookie450]

Quietlybonkers said:

Throttle return springs are easy to see, just under the back edge of the bonnet - and you don't need both of them, so take one off and see if it improves...

That's how we fixed it .....removed the one closest to the bulkhead

[Quietlybonkers]

cookie450 said:

Quietlybonkers said:

Throttle return springs are easy to see, just under the back edge of the bonnet - and you don't need both of them, so take one off and see if it improves...

That's how we fixed it .....removed the one closest to the bulkhead

Mine is running happily on one spring at the moment, ever since Alex suggested I took one off and see what it felt like - answer, a whole lot better under the right foot

[ybt1982]

Cheers guys, I'll try out what you've suggested

Before I go start pulling things out of the engine bay, are there any pictures of said springs so I know what I'm doing

[Quietlybonkers]

I will take you one and post it

[Quietlybonkers]

ybt1982 said:

Cheers guys, I'll try out what you've suggested

Before I go start pulling things out of the engine bay, are there any pictures of said springs so I know what I'm doing

This is the general location, next photo is the specifics

[Quietlybonkers]

In this photo you can see one throttle spring - I have removed the one nearest to the plenum, you can see where it attaches.

[skiver]

[quote=Quietlybonkers]Throttle return springs are easy to see, just under the back edge of the bonnet - and you don't need both of them, so take one off and see if it improves..

You realise the double spring is the traction control system?

[ybt1982]

Thank you muchly

skiver said:

You realise the double spring is the traction control system?

I'm far to much of a wimp to use much more that 1/4 throttle anyway

[ybt1982]

Ok, so I took the 2nd spring of. I love the way it feels, so much lighter on the right foot

But, the noise/rumble is still there Convinced it's the dash, maybe.... is it hard to remove the dash, it's on my list of 'jobs' anyway.

[ybt1982]

Hi again folks.

Ok, so this noise is starting to drive me crazy

I removed the spring as suggested but no difference.

Went for a long drive today and noticed a few things:

1. The noise/rumble/vibration only happens when in gear and clutch engaged. If I have my foot on clutch and rev the engine there is nothing... apart from the lovely rumbling V8 of course

2. If I go really, really slowly up through the revs then I don't notice it either.

3. I think I can also feel it through the throttle pedal

Nick

[Chilliman]

I had a shocking noise from behind the dash, sounded like a bag of marbles. Ripped the dash out but found nothing. Was convinced it was under/behind the dash. Turned out to be the mesh vibrating on the plenum. My plenum is an ACT CF jobbie, but the vibration from the light contact between mesh and plenum was transmitted into the area behind the dash which acted as a sound box and amplified the noise x 10 or more, just the slighted vibration via the mesh sounds like the wrath of hell inside the car.... drove me mad

ETA: bend the mesh up a bit, easy to do, see if the noise stops

Edited by Chilliman on Saturday 1st September 01:32

[venusdimilo]

HI Nick

I had this noise and it was the throttle cable vibrating along the its length and a cable tie around the stepper motor and cable stopped it .

Steve

[ybt1982]

Cheers chaps

I've just spent an hour or so in the garage and done the following:

1. Bent up the mesh

2. Cable Tied the Throttle cable

3. Adjusted the bonnet so it's sits a bit higher when shut. Looking at the heatshield under the bonnet I think the top of the Plenum has been either up against the bonnet or hitting it.

Going to work now but I'll try and get out tommorrow. Fingers crossed it's worked....

[ybt1982]

It worked

Cheers for all the pointers chaps

[Chilliman]

Good news!! It's surprising how good it makes you feel just to get rid of a long standing annoying noise

[taylormj4]

2000 rpm on my car seems to be the point where the engine/exhaust vibrates the most. I noticed it when the exhaust was touching the chassis due to a bad rubber mount.