what is the signs of a bad cat?

[copperpacecar]

removed ALL my emissions controls a few months ago and car loved it and ran great. didnt lose any gas mileage and now my engine looks great but now all of a sudden i got a ton of knock at high rpm. hitting as much as 8 with fuel trims in the +2 to -2 range. everything on the scanner looks exactly the same as it has for the past ffew months except for this knock. im kinda thinking the cat may be to blame as its the only thing left and i have no exhaust leaks but dont know what the signs of a bad cat is. can anyone tell me of shot me other ideas of what it may be. oh and reduced my timing by 2.5 degrees and still getting 5 on the knock sensor. im scared to go fast now. im so confused

 

[Bio248]

if your cat was clogged youd have no power and the car would fight to move up in the RPMs.

you shouldnt have removed all that stuff without tuning it.

 

[Lawngoose]

and it ****s in your house.... oopps wrong cat

 

[Jn2]

normally when you cat is clogged, you would see more boost than you normally would, of course this only appliest if you supercharged...aside from that knocking with a clogged cat sounds right, when mine clogged i saw 3 psi more than i normally get...which was a sure enough sign considering i hadnt changed pullies or exhaust system

 

[machinegunsquid]

When mine was clogged, it was struggling to push past 2-3k RPM, with almost no power.

then again...why have a cat?
Hooray Florida's lack of inspections

 

[TheOtherNick]

removed ALL my emissions controls a few months ago and car loved it and ran great. didnt lose any gas mileage and now my engine looks great but now all of a sudden i got a ton of knock at high rpm. hitting as much as 8 with fuel trims in the +2 to -2 range. everything on the scanner looks exactly the same as it has for the past ffew months except for this knock. im kinda thinking the cat may be to blame as its the only thing left and i have no exhaust leaks but dont know what the signs of a bad cat is. can anyone tell me of shot me other ideas of what it may be. oh and reduced my timing by 2.5 degrees and still getting 5 on the knock sensor. im scared to go fast now. im so confused

If you pulled timing and still have the same amount of knock it is false knock. Check your engine mounts and find out what is clunking Ie dp and sway bar.

 

[copperpacecar]

it is tuned first off...hell i dont even run my car anymore without hptuners hooked up in it. even got a custom mount and im not the best tuner but i think im fair at least. no this ran great with little to no modding of my last tune before removing the emission controls. and i dont think its false knock as i got all new suspension and mounts all the way down to a new rack and hoses. everything is new and the knock doesnt just hit and go away either. at full throttle itll hit every cell with at least a 2 up to an 8. again ran perfect with no knock up till three days ago. any other suggestions then?