Had 02 sensor replaced days before the test. I warmed up the car by driving street/freeways. The 25 mph passed (HC was exactly at limit) while the 15 mph all failed. The HC ppm was 135/92 (measured/max), the CO % was .46/.38, and NO pm was 1009/716. The CO2 was 14.9% and O2 was 0% for both speeds. I plan to do a tune up and replace PCV valve. From searching the web it sounds like replacing the cat converter will help me to pass. I don't care if I foul the cat in a month or a year. I just need the 2 more years that a passed smog check will buy me. The highway mileage varied between 33 to 36 mpg, maybe now it's around 30. Also, the engine was swapped with a used engine about 2 years ago. The car has 180,000 but I wasn't told how many miles the used engine had (supposedly less than 100k). Do you think a new cat converter will get me through the smog check? Thanks in advance.

 

You might want to check for a massive vacuum leak (intake manifold is often the culprit) before having a cat replaced, which is just a bandaid UNLESS previous issues such as misfires critically damaged the cat. Withe 180,000 miles on it, it may have seen its better days. Still, I'd check the vacuum pressure which should be near -19-20 inches of mercury (inHg), first.

 

If it's a California model with an EGR system, the EGR passages in the top of the intake manifold get clogged up and need to be cleaned out. That usually does not throw a CEL. Also check the fuel pressure, and take the spark plugs out make sure they are all the same color. You could have one cylinder too rich and the others lean.

 

Thanks for the replies. I did a tune up today and ordered the cat converter. The suggestions offered are a little beyond my technical experience. If it still fails upon the free smog re-test I may take it to a mechanic. I'm approaching a point where it doesn't make sense to invest more when I could get a car loan and buy a newer car. Or as someone satirically posted online I could buy an '60s car with a V8 and never get a smog check again. The gas mileage would be a hard pill to swallow but I had a 69 Buick Skylark convertible 10 years ago that owns my heart.

 

"The gas mileage would be a hard pill to swallow "

And that pill is just going to get bigger in years to come.