Grr, second pair of cats and after about 2 weeks, it's starting to rattle again. What the hell is wrong? I don't seem to be burning oil, and I don't seem to be burning coolant. It doesn't seem like I have a dead cylinder (all spark plugs show sign of being used). I have new spark plug wires. I can try a new cap, rotor, and a heated O2, but anything else?

Here are my mods. TB bypass, K&N, removed air baffles, shorty headers, carsound cats, flowmaster Force II catback.

I dyno'd it recently, 245HP at the wheels on a Dynojet, AFR hits at the lowest point 11.3 or so.

 

Do these cats require air injection? And if so, is yours working properly - or even existant?

 

Hi,

Yes, it requires AIR. I presume it works, how would I check? The pump is not seized as far as I can tell. The check valves are in order. I guess that leaves the solenoid.

 

if its the pump, i'll give you mine.... athough its probly cheaper shipping wise to get one from someone closer to you..

smog equipment is cheap since half the country takes it off...

 

On my 91 Z28 305, I burned 2 cats because of a bad O2 sensor. The last one was a Random Technologies - ouch! Also make sure that your fuel injectors are not leaking, too much fuel in the exhaust will burn the cats also, at least that's what Random Technologies told me to check when I called them about their cat burning up. Good luck.

 

O2 is a new Bosch, but I just ordered a GM heated. The injectors are fairly new, but that doesn't mean it isn't leaking. I'll change the O2 and check the AIR solenoid as suggested, first.

Thanks for the replies.

 

I lost my cat due to a high rpm backfire. Loud bang, big ball of precious metal dust!!! It cracked and then over about a week rattled itself to dust.