JDS

Having recently fitted a SS downpipe to go with my SS backbox, there is now a noticable noise as I am accelerating through 2500 - 4000 rpm. I have been advised it is not pinking but does sound a little like air escaping. It is definitely not a rattle.

Has anyone else experienced this and do you have any ideas what it can be.

Help please!

Regards,

James.

Fullonloon

Get the same noise (possibly) after having the SS downpipe fitted. Visiting PC for a check-up. Just thought I'd point out that they did not fit the downpipe - I had it done somewhere else. It's like a fast chugga chugga rattley type sound (to give it it's technical name) when accelerating hard. Sound the same to you? Get it checked out.

russell hayward

wastegate chatter ??

Fullonloon

Yes I do have the standard mid-section, with the SS bbox. Perhaps the cat needs hacking out? I think it's the same kind of noise as it happens under heavy accelration too.
Will let you know on Tuesday evening, after servicing.

JDS

Russell, I don't think it is wastegate chatter. I would expect this at higher revs when backing off the throttle.

Fullonloon, obviously difficult to compare "written" noise descriptions but sounds something close, but not rattly.

My initial thought was that it had not been fitted correctly and air was escaping from an incorrectly fitted seal. However, this noise only happens under quite heavy acceleration and I think that the unrestricted nature of the Group A downpipe is being compromised by the standard centre section and its cat.

Fullonloon, do you have the standard centre section?

Regards,

James

[This message has been edited by JDS (edited 05 November 2000).]

JDS

I have spoken to Pete C about this and he assures me everything is OK and the noises I am hearing are normal. It would also appear that my lack of knowledge in this area led me to the wrong assumption about the wastegate. Turns out it is this afterall.

However, I'm still going to go for the de-cat centre section anyway

James.

[This message has been edited by JDS (edited 06 November 2000).]

Dave T-S

It's normal. Does the same on both our MY00 full SS from cat back cars. Sounds like a blowing exhaust.

Cure - went under my favourite M11 underpass (long and narrow) yesterday with it bouncing off the rev limiter in second. Poor mountain biker coming through the tunnel the other way had his ears bleeding hee hee

RichieC

JDS
Does it sound like a leaf stuck in a vent?? (Maybe a big leaf though!!)

Ive got exactly the same on my MY93 with Downpipe and was told, its "the boost building", Thought it may be sticky wastegate but causing no probs, Im happy.

Regards

Richie

JDS

Thanks for the reassurance. The stuck leaf in vent analogy is a good one, this is exactly what it sounds like (not that I've heard many stuck leaves in vents).

I'm not losing any performance either, quite the opposite

Time to enjoy my new system, at least until I get the centre section replaced!!

James.

RichieC

Like it?

Anyway, I honestly dont worry about it now.

Hope your minds at rest, just enjoy scaring old people.....

Regards

Richie