HELP!! 986 rear passenger side rattle
 

I have a 2002 Porsche Boxster Tiptronic
REALLY ANNOYING RATTLE ON REAR PASSENGER SIDE.
I'll try to give as much detail as possible!

After 5 minutes of driving or so, I would get a really annoying rattle in the rear right side when accelerating. It's super embarrassing because it's such a nice car but the sound, just terrible... When I am fully stopped on any flat or up hill ground, and start to accelerate, the rattling is there and when i release off the acceleration, the car rattle fades away. So the rattle is only when I accelerate.

I brought it to a Porsche specialist today and he told me that he wasn't sure what it was and to wait for the rattling to get worse to better pinpoint where the rattling is later.

It did pass smog.
New tires, New breaks, New breaking fluid, oil changed.
Does not rattle when when gassing on neutral or park.
Rattle goes away very randomly and comes back after a minute.
The rattling reflects off of cars. Like if there is a car driving parallel to me, the sound would get louder vs. driving next to nothing.
rattling is still somewhat there when at high speeds but the engine drowns out the rattle.
Today i noticed while driving on the freeway, it was in 5th gear(tiptronic) and i was mashing it, gas pedal all the way and it would take around 1 or 2 seconds to go from 75 to 76, 76 to 77 and etc. Like the car felt slower.

What can this problem be????? I really dont care if the car is a bit slower, but the rattling is driving me crazy........

What a coinkidink- this sounds uncannily like the exact same rattle that my recently acquired '02 base model has!

The rattle in question originates from the passenger side rear end of my car and gets gradually more pronounced as the car heats up. This led me to believe that a heat shield in the exhaust system was loose so I had an indie Porsche garage look into it.

Sadly, it turned out that the passenger side exhaust manifold catalytic converter was damaged and had to be replaced in order to eliminate the infernal and embarrassing rattling sound. As nasty as the phantom rattle sounded, the $2,021 repair bill that's coming my way offends my ears even more! :(

Place a mechanic's stethoscope on the passenger side exhaust manifold cat to determine if this is the culprit behind your car's rattling sound. For your wallet's sake, I hope a heat shield is loose...

The mechanic told me that it could be the cat or the exhaust.
I smacked the exhaust and cat with a rubber hammer but there was no rattling.
If anything, I wouldn't install a OEM cat on. I would use a magnaflow universal cat, so much cheaper. The mechanic quoted me 240 for the repair and 300 for the parts for both rear driver and passenger cat.

If it's the rear cat that's rattling just buy bypass pipes.

unfortunately, I live in California. It's illegal here to do that :(

In that case just get a used one for cheap; buying a new OEM one would be super $$$. I think there are a couple for sale right now in the buy/sell section, and also Woody (username itsnotanova) probably has a couple as well.

Steve

have the same problem. 02 base. ;(

yup, I have the same right rear rattle on my 98. It is most notable over bumpy roads, cobblestone roads. I believe it is a suspension issue, not cats. I'm thinking it may be the strut assembly or a stabilizer bar bushing. Comments?

i replaced my lower track arms and it did seem to help. but the rattle is back, but seems slightly different. also, coming from the front suspension.

my 02 rattles loudly regardless of smooth roads or bumpy.

my 01 has an intermittent rattle from right side but goes away if I pull
parking brake up a notch or two while moving. thinking cables or shoes might be loose?