Passing without cats..I know I know

cobra mk8

Active LVC Member
Joined
Jan 21, 2010
Messages
109
Reaction score
0
Location
Layton
I’m thinking about hollowing out my cats. I’m 100% sure they are restricted due to a pressure test before and after my cats and terrible performance and economy. I’m a poor collage kid and can’t swing new ones or the time to figure out a new system. It’s a 93, the test will be in winter, and I have the pro racer package. Does anyone think I can pass emissions with hollowed cats? I will pick up garbage and plant trees after this.
 
Ya they use the sniffer. I dont know how much room I have on the numbers.
 
I know! the county next to me doesnt. idk what to do about this.
 
Put up a post on the for sale...cats wanted.
Gen ones get scraped around here all the time someone might have a set.
Good luck.....if they are restricted you need to do something before you pop a head gasket.
 
I know! the county next to me doesnt. idk what to do about this.

MOVE or register your car at your friends house on that other county.

your not gonna pass without cats in an emissions county bro
 
I don't know how it is out there but by me you can pass emissions if you have OBD2 car here as long as your CEL isn't on :D
 
I have heard of old hot rod guys down jetting the carb and making it run lean as hell to get through a test. Just a thought.
 
I know! Im thinking I could add some egr and lean it out some with the PRP.
 
Buzzer sounds...

Back in 1980, leaning a car out would/could help

not today...

When you lean out the AF on a gasoline engine, this causes hydrocarbons to go down, BUT.. NOX levels skyrocket.

You might pass on hydrocarbons, but NOX is gonna kick your butt.

cant just "lean em out" any more...sorry to say
 
This little diagram sums it up nicely


AF.gif
 
Just get some aftermarket high-flow cats. They are on ebay for about $60 a piece all day long. The driver's side will be a PITA because of the cat being directly on the manifold, but you could even gut that and put a high flow cat right after where it was.
 
Go to Advance and get a bottle of that...whatever that stuff is...that is supposed to "guarantee" that your car passes emissions test or your money back...or whatever.

Haha. No, seriously, you need to look for some cats that aren't clogged, or register your car in a non-sniffer county. I live in an OBD-II county, but all my vehicles are registered in a non-OBD-II county. And that is a good thing since my '96 has had the CEL on for about 3 years. It's the smog pump. But I haven't had time or desire to replace it. I have a used smog pump in my tool cabinet just waiting to be installed. But I just don't want to mess with taking the front bumper off. Too much of a PITA. Maybe I'll get to it eventually.
 
One thing I’ve noticed is on my emission paper, CO% and HCppm are tested. Just curious, is other states like this? I swear I used to see a NOx on my tests. I’ll have to dig up the old ones.
 
Surprisingly we had 5.0L Mustangs passing up here without cats for a while back when I was at a shop next door to a tester we used. Even my 5.0L Mark VII barely passed with bad broken up, rattling cats. I think they've lowered the test limits now though...
 
This little diagram sums it up nicely


AF.gif



We used to run the tank down to about an eighth full and add a gallon of Methanol and shake the car well to mix to pass the sniffer in So. Florida. They had the latest and greatest testers in the inspection stations at the time. I don't know if it would work now with even newer machines.
 
One thing I’ve noticed is on my emission paper, CO% and HCppm are tested. Just curious, is other states like this? I swear I used to see a NOx on my tests. I’ll have to dig up the old ones.

the inspector next door said 980PPM nox in cars is the upper limit and 1070PPM in trucks is the upper limit.

but I'm not sure I am 100% believing those numbers
 
Gut them and before you have your smog test have two universal cats welded on. One on each side. Unless you can find an awesome exhaust guy like the guy mannieg and I use, if you can find an awesome exhaust guy to do the work right have it done like this...http://www.lincolnvscadillac.com/showthread.php?t=62346 I personally like the spun cats over the universal wide body cats, but it doesn't made a whole lot of difference mechanically, they're just visually more appealing.
 
I wouldn't hollow them out, just cut them off and sell them for scrap. The money they bring should buy you a pair of new aftermarket high flow cats. And hollowing them out screws up the exhaust flow through them.

But I think it probably would pass without cats, as long as they didn't visually look (put in a Ray's switch so they can't fit their mirror under it :D .)

Here are the results from my last test:

Code:
         Hi RPM       Idle
         2410         655
HC       13/180       9/180
CO       0.01/1.20    0.06/1.20
CO2      14.9         14.9
O2       0.06         0.10

As you can see, there's a lot of headroom on a good running car.. And for the record, we don't test for nitrogen oxides here.
 

Staff online

Members online

Back
Top