Failed Emission Test

================ Check the EGR vavle.

================ Check the EGR valve.

What are the other readings for the emissions tests, ie., Hc, CO?

I would check EGR and MAP sensor operation, depending on the results of the test.

High NOx levels are also caused by high combustion temps. Things like high coolant temp, a really lean air/fuel ratio (manifold system leaks), O2 sensor improper operation, EGR system problems (VSV, modulator, hoses), improper timing and spark advance.

Ray, Other readings are passing and they are: HC: 22 CO: 00 CO2: 13.5 O2: 1.3 Dillution: 13.5

By the way, I know the EGR valve looks like a flying sauce thing, but I can not seem to locate it under the hood. Can you please tell me where I can find it (This is a 93 Corolla)?

Thanks, Kenny

This California Smog Check web site lists common causes for emissions failures:

A lean mixture could be due to a bad O2 sensor or clogged injectors. Check ignition timing to make sure it is not too advanced (are you getting any knocking/pinging on acceleration?)

Not all vehicles have an EGR valve. I don't recall if yours does nor not. The EGR valve is generally located near the intake manifold with a pipe leading to the exhaust manifold.

If you have a 49 state version you need to find a California model first. Then it should be easy to find. :-)