Tracking down sounds with Kooks

[Rick-n-Miami]

I've had the complete Kooks setup on my car since late August. I also went with the 2.5" tailpipes and resonator-delete tips to have a true 2.5" exhaust.

I must say, this system is quite loud and aggressive! Also, the power addition of this setup to me, was just as beneficial as the supercharger upgrade. The engine responds much more fast and strong. I highly recommend this upgrade to a supercharged car!

That said, I did find the car a bit loud inside the cabin for my taste. So, I've taken the advise of others and had the car completely dynamated. This did reduce the sound by a good 50% (especially the road noise, moreso than the exhaust), but it's still quite aggressive when I get on it. However, this isn't why I'm writing.

Since day one, there has been a very annoying rattle coming from the center firewall area (I think), behind the dash, when the car hits certain rpm's. It sounds almost like if you get an empty tuna can and rattle a metal screw in it, only a tad louder (really clanky). When I start the car cold, I can hear it best. The car slowly idles down and just as it hits the 1200/1100 rpm range, there it goes. It lasts for a good 4-5 seconds while it's in that rpm range, and then goes away as the rpm's fall. It also occurs (only a much faster vibration) at higher RPM's, such as 2400ish.

My question is, do any other Kooks owners have this noise? Any ideas what it might be?

At first, I thought it might be the dipstick vibrating inside it's tube, but I took it out and ran it without it, the noise was still there. Now I'm thinking that maybe one of the O2 sensors is vibrating in it's place, but I think it's in there pretty tight. Regardless, I need to track down this noise maker and fix it, then I'll be completely happy with the system :)

[shakes_26]

hmm maybe the egr adapter tube, it goes from the header, drivers side, to the egr tube. I know on some header isntalls these are.. well... goobered in there, and this could explain the 'rattling' until it warms up and seals.

Its just below and inboard of the steering shaft as you look from the drivers side. Its a PITA to get to, and probably worse on the Kooks, so it may not have been tightened correctly.

[greggash]

I have the kiiks setup on my marauder.

I just had to replace the cat on the driverside, it puked its guts and plugged up the exhaust.

it did sound like a rattle as you describe,

well, since kooks replaced the cat and the pipe, now I have had an engine light regarding in efficient cats, well, they are =now two different cats and the new one does much less, I have had that test turned off in my tune.

I think you may have a bad cat.

[Rick-n-Miami]

I've thought about the bad cat explanation, but I do not think this is it. For one, it only happens at certain rpms. I'd think if it were a bad cat, it would occur all of the time. Also, I do not have a draw on performance, as I too was getting the bad O2 readings before my new tune.

Just curious though, how did you determine it was a bad cat, and moreover, how did you determine which one was bad?

[TAF]

I've thought about the bad cat explanation, but I do not think this is it. For one, it only happens at certain rpms. I'd think if it were a bad cat, it would occur all of the time. Also, I do not have a draw on performance, as I too was getting the bad O2 readings before my new tune.

Just curious though, how did you determine it was a bad cat, and moreover, how did you determine which one was bad?

How we check for bad CATs:

Clogged -
1) Any check engine lights? If so we scan the PCM and it should tell you which bank is bad/problemed

2) Visually look at the CAT and the heatshield to see if there is unusal burn marks towards the front showing that it's not flowing.

3) We do a probe test...drill a hole in the tubing leading to the CAT, insert a probe, rev the car to various RPMs to see if there is any back-pressure

Broken -
1) Strike the CAT with a rubber hammer and listen for internal rattles which means the bricks inside have broken up.

I hope this is helpful....

[Rick-n-Miami]

You're right, it is a bad cat. I gently tapped on each with a rubber mallet and the drivers side cat rattles, exactly the same sound I've been hearing.

[shakes_26]

TAF is the man!

Hey how have you been? I am still loving the exhaust, and evryone who hears it is impressed. I had it in recently to adjust the driver side rear pipe to clear the 305's, and the guys were drooling over it! They looked like moths around a porch light... the manager was getting irked as all the tools went silent as the whole shop gawked at the shiny pipes. :)

:) Hope we'll see you for SSHS5, maybe you'll get out for the day?

[greggash]

I've thought about the bad cat explanation, but I do not think this is it. For one, it only happens at certain rpms. I'd think if it were a bad cat, it would occur all of the time. Also, I do not have a draw on performance, as I too was getting the bad O2 readings before my new tune.

Just curious though, how did you determine it was a bad cat, and moreover, how did you determine which one was bad?


Mine sounded like a chunk flew off the flywheel for a second, while it was clanking away rythmically with the idle I climbed all over the car to find that the noise was comming from the driverside cat, It got real bad very quickly, and it did plug up for a short time( I was worried about that, limp home) I was spitting pieces of the cat out the exhaust pipes.

But its fixed now, and my tune takes care of turning off the test for cat efficiency, it seems the new cat Kooks sent me is just not exactly the same as before, different model...does much less

Gregg

[BillyGman]

Hmmmm...a very informative thread....and I'm glad that Rick got the problem solved. Thanks to "greggash" & Todd (aka "TAF") for weighing in on that. This is good to know.