Ever since the weather got a little cooler in NYC, my Max has been idling really rough. At higher RPM, anything above 1000 its fine but at regular idle 600 its really really rough.

I also noticed a strong rotten egg smell at the exhaust too.
I just tuned up the car this summer, is the injectors going or something?

 

Catalytic converter is shot.

 

wow thanks for the quick reply, so the cat is also the culprit of the rough idling?

 

could be if its clogged

 

seafoam it. It reduced my nox alot when i didnt pass inspection, which shows it works.

 

I seafoamed once this summer through the brake booster. Then change plugs, wires, cap, rotor and fuel filter. Then ran a bottle of Redline fuel injector cleaner.

I still have one more bottle of seafoam, thinking of putting in the fuel tank little by little.

 

also, do our cars have one or two cats?

 

Just one cat.

And I don't think Seafoam will help a bad cat anymore.

 

how easy would it to buy one of these and install it myself?

is direct bolt on really direct fit?

 

yes its easy as long as the bolts are rusted to hell....otherwise youll have to heat them up with a torch a few times

 

mines were rusted onto the Y pipe, heat wasn't even an option, but i did order my Y-pip with the cat and changed both out at the same time. There is also a $50 rebate for the cat after you send your old one back.

 

just snap the old bolts off and through-bolt the new cat with some 3/8" stainless bolts from the hardware store. they'll last forever that way.

If the heads are ruined on the old nuts/bolts and you can't get them off, use a disc grinder or hacksaw and just cut 'em off.

but yeah, it's most likely a failing cat that's causing the problems. only way to check is to remove the cat. since it's 20 years old, it's likely dead/dying. might as well have the new parts ready to install when you tear it apart.

replacement cat $100
couple flange gaskets (buy the Nissan ones. parts store gaskets are crap. nissan are more $$, but they're good stuff.) $15
four 3/8" x 1.5" stainless bolts $10
four 3/8" stainless nuts $1
8 3/8" flat washers $0.50
4 3/8" lock washers $0.50
anti sieze $3

done.