Catalytic Converters

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by Lonnies94Cobra, Mar 1, 2014.

  1. Need a little help…I just took my 94 5.0 to the emissions and it didn't pass. I then took it to the "guarantee pass emissions" shop down the road for a diagnostic. They told me that the Cobra requires 4 catalytic converters not just 2 and that I was missing the front 2. Is this true? This seems a bit odd to me. Thanks for the help.
  2. Do you have a cel on? Did you pull the codes? Aftermarket h pipes have only two cats but would need a CARB OE approval to be 100% legit. If it makes you feel any better in 96 it went to 6 cats/precats
  3. just weld on 2 cat shells over the top on the pipe ;)
  4. Been there and done that a few times before! Always worked like a champ
  5. Nothing on, so no codes to pull…just the emissions report from Phoenix Emissions station. It passed in NV.

    I was also thinking about replacing the thermostat (seems to run colder, with the needle sitting about on the N of Normal, so definitely the low end). I was going to try that first.
  6. Ok…so I'm new into this, so to clarify…just weld the 2 cat shells over the top of pipe, meaning no filters or restrictions so it would pass visually?
  7. That's what I've heard. Of course, I have no personal knowledge of this. :rolleyes:
    88LX5.Oh, Grabbin' Asphalt and 84Ttop like this.
  8. Might be able to register as historic, could check that out. For Maryland it is 20 years, dunno how old it would have to be in AZ. Some restrictions on use, but again, check it out.
  9. How the hell does welding heat shields over an exhaust tube help a car pass emissions?

    Just pull the spout and it will probably pass.

  10. I would try what kurt said. To clarify, did you fail because of the emission levels or because of the visual?
  11. In Phoenix, OBD-II cars only have to pass a code scan to pass the "emissions" test. But an OBD-I car like your 94 has to pass a dyno-sniffer test. If it failed that test, no amount of empty shells welded over pipes is going to make it pass. Yes, your car did come with 4 cats but if it's properly tuned it'll pass a sniffer test without all 4 of them. Meanwhile, how much timing advance are you running? How clean is the air filter? How fresh are the plugs and wires? What thermostat are you running? Post the test results here for grins and possible diagnostic.
  12. The car originally came with 4 cats. Different states have different rules on accepting the 2-cat replacement pipes.

    Post the test results up to get suggestions on what to check to help the car pass
  13. He said it Passed in NV, ....suggesting it was a visusl failer.
    Is this correct OP??
  14. My car passed phoenix emissions 2 years ago with just 2 cats and no air pump installed, so I doubt it was a visual.
  15. yeah I just passed emissions with no cats here in Phoenix. what did you fail and by how much? here's my check list for emissions.air filter clean, mass air flow sensor cleaned, throttle body cleaned with tb cleaner, clean egr valve, clean Idle air control valve, fresh cap and rotor if they have more then 30k (cheap insurance and I you have ones with a LT warranty then it costs nothing) good low resistance wires, plugs with less then 30k on them and double check gap (also gives you the chance to see how your engine is running based on how the plugs look), clean oxygen sensors (replace every 100k) also check for any vac leaks or exhaust leaks. I also fill up with 1/4 tank 91 octain gas and 32oz of dentures alcohol.
    #15 David Pepiton, Mar 3, 2014
    Last edited: Mar 3, 2014
  16. every year :)
  17. Or just leave them, ....or just buy a stock h-pipe and install it every year
  18. there is no visual inspection in AZ.
  19. It sure sounds like it failed a visual inspection. That's a shame, if it passed the sniff test but failed the visual. I pass with long tubes, 2 cats, dumped mufflers, and no tuning tricks at all!
  20. No, it failed the sniffer test, and then he took it to a mechanic to get it fixed to get it to pass, and the mechanic told him it wasn't passing because it didn't have 4 cats.