I also hear rattles when car is on gear, like when its on reverse or drive. but when i put it in park or just neutral, i don't hear the rattle. I was told that its because of the cats going bad. Is this true or could it be something else other than the cats?

 

It could be your cats. What year and how many miles on your car? I believe the emission warranty is 80,000 miles but I forget how many years. If you are under 80K, you might check with a Nissan dealer.

 

is that what would normally happen if your cats are busted? they rattle? because i brought it to a local auto shop and he said its the cats. And i know it would cost a fortune for some new oem cats. Maybe the guy just wants to make some few extra bucks out of me thats why he insisted that its the cats. But what if its something else besides the cats?

 

There is really nothing under the car close enough to anything to rattle. Maybe a heat shield came loose or something and the lower RPM of being in gear hits it just right to rattle.

But generally when you have a rattle at low RPM or when you kinda bog the engine it's the cats.

If they are in fact bad, get HFC's. They are much cheaper and lighter than the OEM cats.

 

is it bad for the car to be running on busted cats? rattle only happens when in reverse and drive.

 

It wont hurt anything really. You wont pass emissions if you have to test it and it makes your car sound like a POS.

 

oh ok thats all i needed to know because my z is my only transportation. Well as long as im not further damaging the car that means i could still drive to work until i save up enough for new cats.

 

Carson, a standard Catalytic converter has a honeycomb of ceramic latticework on the inside. If this starts breaking up it will fall to the bottom of the converter and can rattle around. My dad had a small rubber mallet like your doctor uses to test your reflexes; he would tap it on parts looking to find stray rattles and such.

Likely the mechanic tapped the bottom of the cat and heard the broken pieces rattling around, if so he is correct in declaring the converter to be going out.

Your car has two cats, one for each side of the engine; did he say which one was bad? It’s not a great idea to continue to drive with a cat that is breaking up as it could become completely plugged with the broken pieces stopping the all exhaust flow.

 

oh well, i guess im going to be on foot patrol for awhile. haha
Life is good.

 

cats
cats
cats
cats
cats

 

Catalytic converters nowadays rarely break. If the catalyst structure inside disintegrated or crumbled, the exhaust gas composition would change significantly and the change would trigger a related DTC. So, if there was no DTC, it's unlikely that they were damaged.

Look for other source of rattling, heat shield is a more likely candidate.

 

Catalytic converters, reliable and long lived as they are, can and do fail by having their inner structure break up. Huge companies like Walker and a half dozen other exhaust specialists do a hefty business supplying universal-fit converters. Muffler and exhaust shops keep the replacements in stock at all times as they replace al lot of broken converters. Depending on how hard a life the converter lived and how many times it smacked speed bumps they can and do crack and break up internally. Converters are tenacious and even though hunks of the ceramic have broken up, the structure at the front or back may stay intact for a while keeping the check engine light at bay for a time. Ultimately if every thing but rear honeycomb breaks up the pieces will plug it up restricting flow, if everything but the front breaks up bits of ceramic will lodge in all the downstream exhaust components.

Nobody can conclusively diagnose every little glitch or rattle over the Internet, but it’s not too hard for a professional mechanic to isolate this type of problem. Emphasis on “Professional” mechanic.

 

8years or 80k

 

A defective cat will eventually clog up and cause you to lose power and stall. I drove on a bad cat in my Nissan Frontier for about a year before it caused the vehicle to lose power at 40mph and stall completely. Then again, i had a secondary problem develop, which contributed to the cat going bad quicker. A missfire. Just a heads up...

 

would a different year catalytic be compatible with a 2004? probably 2005 to 2008?

 

i would think up to 06 will work, i know for a fact 07 and newer wont because the way they bolt to the header

 

Ok ok. Thank you all for the answers.