49-state legal, direct-fit: $118 https://www.ebay.com/itm/253120020746
CA-legal, universal: $776 https://www.ebay.com/itm/304044103436
CA-legal direct-fit: $1048 (!) https://www.ebay.com/itm/174087409201
> The vehicle ECU monitors the exhaust composition before and after the first catalyst. Downstream, the performance is not monitored by the computer. afiak the ECU doesn't have the capability to monitor nox and hydrocarons directly. The reason for this is that a cheap, reliable oxygen sensor is employed for monitoring.
I don't see what any of this has to do with smog tests, and it's not even accurate for all vehicles (pre obd2 has just a single narrow band o2 sensor before the cat) but this is completely off-topic. The tests shouldn't rely on the vehicle's systems for measuring emissions, it just creates more opportunities for fuckery.
CA smog tests use their own emissions monitoring equipment and have already employed rolling roads to put the vehicles through varying loads during the test.
>I don't see what any of this has to do with smog tests, and it's not even accurate for all vehicles (pre obd2 has just a single narrow band o2 sensor
You mentioned the smog tests, saying if the vehicle can't measure them they aren't worth a damn
>If the smog checks are worth a damn it shouldn't be necessary to certify the catalysts; if the cat isn't working, the vehicle should fail its regular smog test.
Thats why it is not off-topic.
No cars monitor for the smog gasses. That's why Cali uses a special sniffer and a dyno to run a load test. In order to accomplish their stated goal of reducing pbotochemical smog, they must employ a dyno to test under load to monitor the production of nox and hydrocarbons out the tail pipe.
The oxygen sensors pre-obd2 were never used in any state for emissions, In my state we did a 2 speed idle test on a dyno which is being retired currently as all required vehicles are now exempt from this test.
We still are running oxygen sensors for engine management in every car. They do not sense any smog gasses.
- check engine light
- fault codes
- readiness monitors
its a legislative joke.
In EU even a 20 year old bmw e36 cat still goes for ~$1K, because we actually test emissions.
I bought that ebay cat last year after my cat was destroyed in a U-joint failure when the prop shaft impacted it at speed.
It is not empty, and the car passes a CA sniffer test with flying colors using it.
It is pretty cheaply constructed though, thin walls, and the ID seemed a bit smaller than stock so not great for power.
The cheap ones are less resilient as you noticed. When hydrocarbons (such as from blowby or imperfectly metered fuel) hit the substrate it works against the catalyst chemistry and the catalyst produces combustion clearing it up. But this skyrockets the temperatures, damages or melts the substrate reducing its effectiveness using up the substrate. There is a lot of expansion and contraction in a 1000-degree cat, failing ones can double that, so the poor bonding techniques will turn it into a rattle can fast.
Thin walls, less substrate, and poor bonding lead them to fail prematurely.
Good luck.
>if the cat isn't working, the vehicle should fail its regular smog test.
The vehicle ECU monitors the exhaust composition before and after the first catalyst. Downstream, the performance is not monitored by the computer. afiak the ECU doesn't have the capability to monitor nox and hydrocarons directly. The reason for this is that a cheap, reliable oxygen sensor is employed for monitoring.
Maybe it's possible to add that regulation federally.