Engine noise in AU Interior

duaned · 08-03-2007, 11:35 AM

Quick story. Something which is constantly bugging me each time I drive the AU is a " hissing" sound that is clearly audible under accelaration which seems to be coming from the driver's side floor area. It sounds similar to driving a car with a rubber grommet etc. missing from the firewall allowing engine noise to enter the cabin, but from what I can see, all is OK here. What I can say is however I noticed it straight after driving the car once the Pacemaker 4480's were fitted (revised type) and high flow cat. I have changed to a 3inch metal cat. thinking it may be the cat. they fitted with the extractors but to no avail. I have also had JMM headers and the original 4480's on this car and this hissing sound was not evident then. The exhaust has been checked by 2 exhaust experts both saying there is no leaks in the system. Doing a search discovered another forum user has this issue as well but got no reply from his post so I thought posting in this thread may attract someone who has a fix or ideas for this issue of mine.
Sorry for the long post!

Duane.

LG · 08-03-2007, 12:17 PM

Could be an exhaust leak somewhere?

Also, what did you think between the JMM headers and the 4480s?

Cheers

StAndArdAU · 08-03-2007, 04:48 PM

had my 4499's fitted on tuesday and now notice this hissing as well. doesn't pi$$ me off though so i'm well prepared to live with it, i listten to the stereo loud anyways.

but yeah i would't mind knowing wat it is making the nmoise also.

ClassicAU · 08-03-2007, 05:20 PM

i had extractors, a new cat, and an exhaust fitted a few weeks ago. I have also noticed that there is now a sound which i can only describe as sounding like water flowing through a pipe! I guess this is the cat, so i would imagine that this would be the first place for you to look?

Evan

bodes-sh · 08-03-2007, 08:11 PM

i've got what i think would be the same thing ph4499's, new act, etc, took it to an exhaust shop and got them to look at it and they reckon it's called "extractor noise" basically where the pipes go 2 into 1 and it's normal, whether this is true or not i don't know, but i just ignore it

duaned · 08-03-2007, 11:03 PM

Quote:

Originally Posted by LG

Could be an exhaust leak somewhere?

Also, what did you think between the JMM headers and the 4480s?

Cheers

Tell you I havent really noticed any difference in performance between the two but honestly I should have keep the JMM headers.I didnt notice this noise then!

LOL about the exhaust leak. I mentioned that there were no leaks and by two exhaust companies! :hihi:

b2tf · 08-03-2007, 11:05 PM

check that the extractor bolts havent come loose, sometimes when theyre first installed they do need tightening up after a few kms.

duaned · 08-03-2007, 11:06 PM

Quote:

Originally Posted by ClassicAU

i had extractors, a new cat, and an exhaust fitted a few weeks ago. I have also noticed that there is now a sound which i can only describe as sounding like water flowing through a pipe! I guess this is the cat, so i would imagine that this would be the first place for you to look?

Evan

LOL, I mentioned I have already changed the cat for another which didn't solve the problem! But I can highly reccommend a 3inch metal cat. The exhaust noise with the redback cat back is sweet!

HLC · 08-03-2007, 11:11 PM

after i got my cat-back exhaust put on..

when i accelerate through the rev range, a hissing/whistle can be heard around 3grand+ then goes away as i hit redline.

i cant seem to find a leak in my exhaust. sounds like its coming from around the flange area though... hmmmmmm