Ok so here is the problem, when Im driving and start to de-accelerate I can hear a loud rattling noise comming from my car. It only happens when the turbo is spooling down. If I put the car in neutral and rev it it only makes the noise on deceleration if the rpms go above 2000. I've narrowed it down and its comming from the turbo side of the car from either the cat or the turbo I can not tell which one. Other than the loud rattling noise the turbo seems to be fine since its boosting to 24psi

 

Sounds like the wastegate is going. Alternatively it could be broken/loose honeycomb in the catalytic converter.

What turbo are your running that it is boosting to 24 psi? That is high !

 

holy god the 24psi is not good for the lil KO3 man

 

lol look at his sig. k04

 

haha im running k04 pc-16 not the k03, although my friend with a 98 1.8 has the same problem with the rattleing noise too

 

Wastegate fo sho. I know someone who had this problem too when you hit the gas it only rattles when you take your foot off the gas. OR if you rev it from the engine bay on the throttle body and let off is when it rattles. THere is a lock bolt on the wastegate arm that i think may have come lose from the threads and its flopping around on the wastegate arm/actuator. WHich means that eventually the wastegate will start ****** up and boost will be affected. This is all a mad scientist theory that i have nothing to back up with, but whatever.