Xtreme864

iTrader: (15)

So i'm at the exhaust shop today getting new tips put on. After it's done, i'm getting a quote with the guy there to see how much it would be for true duals from my headers back to dumped bullets. He proceeds with telling me about how its against federal law to remove cats, and i'm like yea i'll take my chances. Then he goes on to tell me that removing your cats will cause the 02 sensor that plugs into the cat go bad and cause your PCM to dump too much fuel in your motor and will basically destroy it. Even went so far as to tell me he saw a lady one time with no cats melted a piston. Am i wrong in remembering at least several dozen people just on this site alone that are running true duals setups with no cats? Do you have to get your PCM tuned if you take your cats off? Can't you just bung the straight pipe and stick the o2 sensor back in? I've never heard of having to tune for exhaust setups, but i could be very wrong?

Blackhawk777

You will need some tuning so you won't set a check engine light. even if you bung the exhaust tubes for sensors, it'll set off a code for abnormal readings

Xtreme864

iTrader: (15)

yea but melting a piston just because the cat was removed? I've never heard of that in my life.

gotcam350

you are removing one more of the catalytic converters and will trigger a check engine light i believe , im pretty sure the check engine light is easiliy fixed by having it tuned,if thats what you mean melting pistons well anythings possible i suppose

gotcam350

well i never get a check engine light for some reason sense i had it tuned. anyone know why?i can unplug any sensor in the engine and never sets off a code.and still passed emissions

raysadude

iTrader: (11)

installing race headers and take off cats would set the check engine light on and most likely cause your car to run rich since the O2 sensors reading is messed up..i did a dyno tune right after i installed my exhaust(headers, X pipe with true duals, bullet mufflers dumped before axles)

i'm not saying that a tune after exhaust installation is necessary but it could help make your car run right.

01ssreda4

iTrader: (96)

what are you talking about? everyone here runs cats

T AM

iTrader: (5)

He's probably just saying that to discourage you from doing it, because its illegal for him (the shop) to take them off.

If your not worried about emissions you might as well get longtubes and buy the tsp true dual setup. I think that would make more sense then installing headers later and having to redo the rest.

98ssconversion

i dont run cats? this guy is a fool ^^^^ (complete and utter joke) It should through that check engine light till you get it tuned. Melting pistons though? Uhm never heard of that problem. They do run rich though, I have yet to get mine tuned cuz I have other stuff on the way and its obvious that its in need of a tune. Most places around here wont take off the cats though unless you tell them its OR. So he knows whats up but I wouldnt worry about a pistons shmishmelting...

Xtreme864

iTrader: (15)

^^ same thing i figured. We don't have emissions in this state and never does a cop pull anyone over for exhaust, since most cops around here also drag race at the local track.

We've got the tools at my buddies house anyway so i'm not worried about it, just gotta find time (and money) to do it myself.

98RedBird

iTrader: (77)

Well one thing he said was true... it is against federal law and he is subject to a rather sizeable fine if he is caught doing work that removes the catalytic converter. Anything after the cat is fine but he cannot touch the cat unless he is replacing a non functional catalytic converter.

Now, onto everything else he said... pure and utter BS.

98ssconversion

Its all about finding the right shop. When I had mine done the guys was just like this is for track only right? (wink) And of course I responded with an absolutely and off they went!

Xtreme864

iTrader: (15)

^^ Works for me. Think i just need to suck it up and do it myself lol, just would rather get people who do it daily to do it, but i mean if i do it myself, i not only save install costs, but can only blame myself if something isn't right haha. can use the money i'd save in labor for tuning.

98ssconversion

there you go! now your thinkin!!

Mumbles

iTrader: (5)

LOL. I know, I do.

the_merv

iTrader: (88)

Running rich actually causes Cylinder temp to get lower compared to it running lean..I'd rather run rich than lean. You will burn a Piston up running it lean.

Oh yea I have Cats too.

Formula96

cats have nothing to do w/ your air / fuel ratio, the only thing they do is clean your exhaust fumes, the reason it causes a check engine light is because your rear O2's (only used to check that your cats are working) are reading a rich (to them) situation.

FormulaZR

iTrader: (7)

The front O2 sensors are the ones that have the most affect on your A/F. The rear O2's are monitors to make sure the cats are doing their job. You can either have the rear O2's tuned out of the car, or use O2 simulators. I have no cats on my car, and haven't for 68,000 miles...and guess what, no issues.

That being said, yes, it is illegal for them to actually do the work. Your best bet is to get the kit from a place like Texas Speed and do it yourself.

http://www.texas-speed.com/shop/cate...MID=1&catid=56

BlackScreaminMachine

iTrader: (17)

Well the exhaust guy is right in a few regards. It is ILLEGAL for him not to replace a CAT with Another CAT. Now some places break the law, some let you do the work and state, they cannot be involved, and some take their work home just incase. One place local out right refused, another let me do a "Test Pipe" to see if the CAT was clogged, I just didnt have to go back.

The PCM, if un adjusted, freaks out because the readings are off and will at most times add more fuel, or take away. It is not seeing the diff the CAT would make for the A/F ratio.

As for melting a piston, it should not but, again, it depends on the car and who makes it.

When you "un cork" a exhaust set up, the A/F from my exp, tends to lean out as back pressure has lessened and scavanging has impoved and adding fuel to get the car back at the correct ratio @ WOT often shows a gain.

Stock cats on 98+ Fbodies tend to be not as restrictive as past CATs were, so the gains is still debatable. I say getting rid of the Y pipe with the flat spot is more important.

But again, thats my opinion.

Epic1

Whats all this talk about underground cat running? I want in!


but yea he just doesn't want to do it. you'll get a check engine light that only needs a tune to get rid of.