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Discussion Starter #1
A friend of mine just picked up a 1999 California car. It's now throwing a code suggesting the front catalytic converter is toast.

We are up in Canada and (obviously) not subject to the California CARB stuff - how do we go about deleting all of it so that the car becomes a non-CARB spec? What is different between a CARB and non-CARB car besides the front cat?
 

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There's some o2 sensor stuff you gotta mess with as well. I don't remember the exact details been a long time. But that's really about it. At least it gives you something to search for. :)
 

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Discussion Starter #3
At least it gives you something to search for. :)
Thanks! I've done some searching here and elsewhere and I'm not turning anything up. Perhaps I'm having a bad search day.

So delete pre-cat and the first (?) O2 sensor? Likely need a different ECU / tune then so it's not looking for the other O2?
 

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Just dealt with this myself. You have two options:
Install a NB2 (or fed spec NB1) Headers without the precat. Weld in an additional o2 bung after the secondary cat and lengthen the o2 wiring. This is a big upgrade from the CA Spec boat anchor headers to the tubular NB2 header design.

If you are trying to stay CARB legal you can wire in a resistor to the first o2 sensor. This will trick the ECU into thinking the cat is ok. Like this

 

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Discussion Starter #5
Just dealt with this myself. You have two options:
Install a NB2 (or fed spec NB1) Headers without the precat. Weld in an additional o2 bung after the secondary cat and lengthen the o2 wiring. This is a big upgrade from the CA Spec boat anchor headers to the tubular NB2 header design.

If you are trying to stay CARB legal you can wire in a resistor to the first o2 sensor. This will trick the ECU into thinking the cat is ok.
Thank you! Is it possible to delete the other O2 sensor all together? We don't have anything to do with CARB up here.
 

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Without two O2 signals to the ECU, any North American Market ECU will throw a CEL.
 

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Discussion Starter #7
Without two O2 signals to the ECU, any North American Market ECU will throw a CEL.
Got it. I think I misunderstood Armfish02's message. The resistor is to trick the ECU without fixing the bad cat. If we delete the cat and move the O2 sensor behind the remaining cat that's regular "NA" spec?
 

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Yep. :) Sorta.


You might need to do both. Or move it and swap to non-CA ecu.


Federal emissions NB1s still had two o2s. One pre-cat and one post cat. But they only had one cat, so the expected readings are different.
 

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Discussion Starter #9
So ...

  1. Delete precat
  2. Relocate O2 sensors (one before one after remaining cat)
  3. Install fed-spec ECU
 

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I believe the secondary cat on a CA Spec car is smaller than the federal cat as well. So if you delete the precat you may need to replace the ca cat with a federal one as well to pass the Sniffer test (if you're in a state that requires it) ..... or add in the resistors
 
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