Porsche 2001 996tt with 59,000 miles: On start up i hear this loud chirping/banging sound coming from the back right side of the car. As the car warms up the sound goes away after about 5 minutes. However, it returns with accelaration. If i look under the car the banging sounds metalic, sounds like it coming from the turbo or catalytic converter area, maybe even the exhaust. My performance is fine, no change. Its not smoking, i have plenty of power. Any suggestions as what it could be?

 

I'm guessing clutch or flywheel issue?

 

Hope it's not a spun rod bearing. Is it a knock that increses with RPM's?

 

possible bad cat ?

 

Boosttt: Sometimes yes and no. If i keep accelaration constant then no, if i get on it then yes; sound level stays the same but frequency increases.

 

Had clutch replaced about 20 months ago.

 

Spark plug will be knackered - had it several times before. Normally it is the ceramic part that has either cracked or come away. This is the reason why I don't use Densos anymore!!!

 

Oh dear, i just had denso fitted with advice from this forum oh well

 

yep it's a spark plug couls just be lose happened to me just like yours at start p on on acc...

 

For a lot of people they seem to work, but the one set I tried had one spark plug that broke up. Just not prepared to take the risk, and I have seen other threads with similar reports on Denso. On the otherhand people are running them with no issues.
Maybe just unlucky but they are definitely never going back in my car.

 

Thanks, i will take a look at the spark plug and i am hoping you are correct! I will let you know.

 

I never had a spark plug go out, but what would be banging? (Bosch NGK) Wouldn't it just be missing and running rough? He said no change in performance. You can hear a knock easily if you use a heater hose or something and use it like a stethascope and listen around to find the source of the noise.

 

Maybe a belt pully / power steering pump? Some reports of them making strange noises.

 

Dont need a hose, the noise is LOUD/Chirping.

 

The noise seems to be coming from belowthe belt.