Originally posted by ChiliSVT:
just because the computer thinks that my car is legit, doesn't it still blow bad air because the cat really is bad? I don't understand how I can pass if it blows poorly.
Chili <---------- feeling like an idiot
Depends on which testing program is in effect in your local area. The following applies to the St. Louis and Kansas city ENHANCED inspection area. Your testing protocols may be similar or they may be different.
Because current federal standards require a fuel cap test and an OBD-II scan. No sniffer or treadmill test is performed on OBD-II equipped vehicles.
Vehicles in the BASIC testing area (more rural area outside of the metro area) get the fuel cap test and a basic idle/sniffer test.
In any event, there is a final catalytic converter that is after the precat(s) that does a pretty good job of cleaning the entire exhaust stream. The pre-cats were added to help, especially with cold engine driveaway emissions. Since they're very close to the engine, they warm up to temp much more quickly than does the main catalyst and begin cleaning the exhaust much more quickly.
The computer only monitors the performance of the pre-cats, not the main cat.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
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