I'm keeping this separate from the project supra thread (which I've neglected for a month or so) as its more of a general question as to what to look for next.

My issues with the CA smog process aside I took the car in for its smog check and didn't pass on the HC. The max was 84ppm and I ran 127ppm. This was at 15mph. Prior to the first test I replaced the catalytic converter (second one).

After the test I replaced the o2 sensor with the hopes it was just an issue with it being 21 years old. Re-test and didn't pass the 15 mph HC test and ran 193ppm (it jumped?) and also am now having issues with the NO. The first test I measured 219 ppm and the second test it jumped to 562ppm.

I don't think the EGR all of a sudden went crazy and am wondering if replacing the o2 sensor would have caused an increase in the HC and NO.

The car was at normal operating temperature for both tests. Not quite sure where to go from here. I'm replacing the front o2 sensor as well but don't think that will help given the results after replacing the downstream one.

Thoughts?

 

Our Toyota Master Ace had a lot of NO problems in passing smog. We traced it to a vacuum leak.


Are you running lean?


For HC:
New caps, rotors, plugs.
Clean injectors

 

Should have got a TDI VW!

 

Probably posted a little early as I'm going to check if its running lean/rich this weekend. I was surprised by it being worse off after the o2 sensor was replaced.

That VW software would be a big help.

 

Common with older toyotas

Took 6 months (after extension and numerous failures) to get our master ace through

 

The Primary (first o2s) do the majority of the trim work for fuel than the secondary o2s. I would look into those, along with plugs/ wires, and air/fuel filters. Also like above look for vacuum leaks.