bluecmaro96

ok my cats are clogged and i need to get the dealership to replace them, this is weird because carfax says the cats were replaced twice already and the car has 30,000 miles on it. would clogged cats make my times worse? ok does this make sense, please dont poke fun if im incorrect but, when i put my finger inside the tips on the gmmg i have black stuff on my hands, doesnt smell like oil, it looks like carbon, i think what is happeneing is since the cats are clogged the exhaust gas is too much so the plugs cant burn it all off and its making it carbon up, i pulled a plug and it was pretty black, granted they are still the stock plugs even after 30,000 miles, any suggestions, i appreciate all the help

Country Boy

iTrader: (24)

Look at it this way..... can you blow through a plugged straw? Thats what you engine feels like The black soot is normal in the exhaust pipes. Its a product from combustion.

bluecmaro96

why would this car have the cats clog so many times? twice before i even got my hands on it . smells like rotten egss when i start it, doesnt sound right either kinda sounds.... weird cant even explain it

distortion_69

iTrader: (20)

Very possibly is running rich. Do you smell gas? Do you have any mods? Several boltons on the ls1 will make it run a little rich. In order to kill cats so quickly though, you'd have to be running pretty freakin rich.

Peace,
Josh

bluecmaro96

it was stock when i got it its a 00 trans am with gmmg, slp lid, ssra, it needed cats at like 8000 miles and 15-18000 miles, now it has 30,000 i didnt think the gmmg would make it rich.

bluecmaro96

ok i have an idea, if i autotap it at wot and check the af gauge and bank 1 sensor 1 and bank 2 sensor 1 o2s what should the number be at wot? and what should the af at idle be? and af at wot? thanks

jimmyblue

iTrader: (11)

I don't believe dry carbon is clogging your cats,
nohow.

Look for 900mV O2s at WOT (factory might be
set leaner than this for smog, dunno about LT1s).
Under 850mV or so expect bad pinging. Over 920mV
and your true mixture is anybody's guess, just way
fat.

Black plugs mean your problem is with fuel or spark,
the cats are just victims, not the culprit. If in fact
there is even anything wrong with them at all, that
a sane mixture wouldn't burn off right quick. But
with a messed up situation like this you may have
fouled O2s as well (the rich get richer). 'Tap the
prime sensor outputs (MAF, MAP, TPS, O2s) at
idle, cruise and WOT. Make sure none of them look
lazy / dead.

bluecmaro96

when i drive my car it smells like sh** kinda like rotten eggs/sulfar i know the cats are clogged, and at 6070 i can feel kinda like a surge seems like on top end its not doing as well as it should, i seen on carfax that the cats were replaced twice already, once at 8000 miles once at 15000 miles and now it has 30,000. this is weird