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Old 12-11-2017, 05:53 PM   #8 (permalink)
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Thanks, California98Civic!
Can you please give me details on the cat cleaning procedure? What product exactly (Amazon?), and where exactly put it in and how? Thanks!

In the interim, a mechanic discovered that the exhaust pipe was missing the second catalytic converter, and put in a new CA C.A.R.B. approved aftermarket cat into the exhaust pipe below the car for $100 part + $50 labor.

I remember that some threads on this or similar forums suggested that there was no second cat on the VX, while others disagreed. I have two more Civic VX's - one has a second cat and a resonator, the other has a resonator but no second cat. The car in question had no second cat nor resonator underneath. A certified CA smog + repair station was first surprised about my newly installed second cat and refused to work on it due to modifications, then looked up the part for this car and confirmed that is was the right part.
This is all very confusing. The diagram on is not clear to me either. I don't see the second cat listed as a separate part.

IF we assume for the moment that the car originally had, and should have, a second cat, can someone perhaps educate me what is the difference in function between the primary (at the exhaust manifold) and the secondary cats? Do they just work in tandem to eliminate a higher percentage of the gases, or is one responsible for one type of gas and the other for another pollutant? I am having a hard time finding information on this, and most discussions on this forum just mention "the" catalytic converter.

If there is doubt whether all VXs had a second cat, can you VX owners please peek under your car if you guys have a second cat? (As I just learned, the cat is not to be confused with the resonator, which has a more round shape and is typically further to the rear in the exhaust pipe. The resonator and/or catalytic converter may or may not be on the cars after exhaust pipes were replaced.) Thanks in advance!

Regardless of whether or not the car should have a second cat and whether the mechanic putting it in did the right thing, the car also has significant less power accelerating than my other VX's. That means something must be SIGNIFICANTLY off. However, no check engine light. (Check engine light is working, but shows no code.) Several mechanics already found every conceivable part related to exhaust working, except the car has ca. 280 HC at 25 mph, AND significant loss of power. At least one mechanic confirmed that he did a compression test.

The engine bay looks almost sparkling new, car looks immaculate, and the car has only 190k miles.
Federal car, 5-wire O2 sensor. Should pass smog in CA according to the information on this forum, if all parts are working. EGR valve, throttle body, O2 sensor, spark plugs, wires, PCV valve, and rotor are all new with the best NGK/NTK parts where available.

I made an appointment for tomorrow at the dealership for a full diagnosis. I don't know if their diagnosis will be more exhaustive than the one of the smog+repair station. I'm afraid they come back with no result either, and/or refuse due to non-availability of Honda parts (catalytic).

If the dealer's diagnosis is non-conclusive, I guess the next thing to replace is the primary catalytic converter. The HC values stayed almost the same before and after putting in the secondary catalytic (under the car). Question: Is it possible that replacing the primary catalytic with a C.A.R.B. approved aftermarket catalytic will fix the HC, if the secondary didn't move the needle a lot?

What are my other options? Giving up and take the loss? I paid several thousands for the car.

Any help is very appreciated!

Last edited by comegetme; 12-11-2017 at 06:08 PM..
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