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Discussion Starter #1
Our '96 v-8 t-bird failed an emission test today. The HC was 53ppm,two and three years ago it was only 24 and 10ppm.The NO was 9ppm three years ago,two years ago it was 186ppm.Today,the NO was 244ppm (max is 409).We did have to gut one pre-cat due to it self destructing when a broken vacuum line caused several cylinders to lean misfire,which led to raw fuel igniting in the cats (and doing a meltdown).The vacuum line may have been an increasing hidden leak for several years before the big breakaway.Today's failed test seems not related to a gutted cat because cats are supposed to control NO more than anything else,right?The car currently has MSD ign wires,new plugs,clean air filter,new fuel filter,Dynomax dual exhaust,no vacuum leaks,and all original maf and oxy sensors. Fuel mileage around town is poor,averaging 13 to 14,but freeway mileage goes up to about 23mpg. I am thinking (guessing) that if the oxy sensors are "slow" maybe that degrades city mileage,wastes fuel and raises HC levels.What do you guys think? Also,would cleaning the maf have an emissions advantage?The car starts easily,has pretty good power,does not show a check eng light,and has no stored codes.I would like fix the problem and pass with a large margin.I've got four weeks until current registration expires.Every good tip would be very appreciated!
 

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no it isn't for just NO... its for everything. This is taken directly from how stuff works.com
A catalytic converter is a device that uses a catalyst to convert three harmful compounds in car exhaust into harmless compounds.


The three harmful compounds are:

Hydrocarbons (in the form of unburned gasoline)

Carbon monoxide (formed by the combustion of gasoline)

Nitrogen oxides (created when the heat in the engine forces nitrogen in the air to combine with oxygen)

Carbon monoxide is a poison for any air-breathing animal. Nitrogen oxides lead to smog and acid rain, and hydrocarbons produce smog.
In a catalytic converter, the catalyst (in the form of platinum and palladium) is coated onto a ceramic honeycomb or ceramic beads that are housed in a muffler-like package attached to the exhaust pipe. The catalyst helps to convert carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It also converts the nitrogen oxides back into nitrogen and oxygen.

It sounds to me like your other cats are going bad on you.
 

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Discussion Starter #5
Thanks! Yes, I got the info now too. If I could just get a source for good condition used cats we would be home free! Believe it or not, re-certified used cats are legal in Cal, but they still cost about $500 a set outright. A few months ago, I sent Summit back a Catco system (not legal in cal) due to severe bad fitup. The only system that seems to fit is a Ford factory setup. All the local wrecking yards have to cut thru the systems before cars enter the yard, and they can't legally sell a used set either. It looks like a big snafu for me.
 

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yep california is ghey. Stupid emission laws....
 

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I paid 650 for my refurb cats , and I got the you got raped stuff from people .

looks like prices are coming down . lol
 

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A couple years ago there wasn't any place that was selling used cats (OBDII compliant) for my T-Bird. At the time, my Dad owned the car and the cats went out. He went to get them replaced and he was told that the only way to pass was to get genuine OEM replacement cats. So he went the Ford route and paid a nice $980 for the 3-cat Y-pipe assembly, and then $75 for an install. All I can say is...ouch! :eek:
 

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you could always go to the for sale forum. i think a while back i saw somebody had exhaust components in there for sale. get a set from somebody doing a no cat conversion?

just a thought.

jamie
 

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cats - cheaper wishbone

Just replaced my wishbone with 3 cats.
If you have a connection, you can get all 3 replaced for about 400.

Tip: exhaust pipes are extremely rigid; if you want a good seal, have your cats rebuilt, not get someone else's that might be off just a little. No amount of cranking on bolts will eliminate the HOG sound.;)
 

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try replacing the O2s first i would try that. Ive had cars that had exessive emmissions and i just changed the O2 sensor and passed with outstanding low emissions...but cali is strict so the cats may be holding you back. I would just pop some new O2s on then take it thru a test...then if it still fails get new cats! If you get just new cats without replacing the O2s you could still fail.
 
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