Strange noise.....suggestions Please

[rickf_uk]

For a wee while now my LS1 'Ro has been making an odd noise under acceleration. As I accelerate away from standstill I get a metallic "fluttering" noise, particularly between 2-3500 revs. The noise goes above 3500 rpm and can't be heard when the car gets up to a constant speed. Also there is no sign of the sound at tick over or when the car is revved while standing. Something at the back of my mind is saying it's either the induction system or the rockers but I'm guessing.

The car is going in for some work in the next few weeks so it would be a good time to get this ironed out.

The car has a K&N induction system,Pacesetter 1- 5/8 long tube headers, and a bimodal de-cat exhaust. Oil pressure wise I'm getting 32-35 at idle and 40-45 under load.

Anyone had similar noises or do any of you technical bods know what the problem is?

[ads_green]

When I've had this it's been things like the exhaust fitted to tighly and buzzing.

I'd say that as it doesn't do it at tickover and only between a set range this would suggest not a mechanical noise as I'd expect those to stay with more revs.

[rickf_uk]

ads_green said:

When I've had this it's been things like the exhaust fitted to tighly and buzzing.

I'd say that as it doesn't do it at tickover and only between a set range this would suggest not a mechanical noise as I'd expect those to stay with more revs.

That sound hopeful Adam, and more important not expensive!

Anyone else?

[MadMaxHSV]

I get a similar noise since installing my headers on acceleration from low revs. Put it down to being normal with thinner stainless headers after reading around. Although the ECU occasionally picks it up as being knock.

Out of interest how can the exhaust be done up too tight?

[ads_green]

As in the wrong rubber mounts being used and bolted to them soo tight that the mounts don't dampen the vibrations so the exhaust buzzes. The exhaust should be free to move about a bit like the engine and not clamped tight to the chassis.

[v8_interceptor]

I had similar with exhaust pipes rubbing.... I'd check that out as was known to be a common one

Edited by v8_interceptor on Tuesday 11th August 20:49

[rickf_uk]

Many thanks Guys. What you say would tie in with the noise appearing shortly after the headers were fitted. I'll let you how I get on with finding a cure.

[motomk]

A noise I got when putting on one make of catback exhaust turned out to be the spare bungs (bolts) in the pipes where you can stick wideband sensors which just needed tightening up.