This morning my '91 sentra SER (well maintained 140K miles) failed its CA
> (test only) smog test. I had just previously put in new NGK (i.e. factory)
> plugs, a new air filter and changed the oil. I had also retarded the timing
> to the maximum legally allowable. Any ideas on what I look at next? I think
> the O2 sensor is probably okay, because I replaced it only 2 1/2 years ago
> (and also the smog tech said the test results suggested it was okay). >
> I failed on HC's at both 15 and 25 MPH (very marginally at the higher speed)
> and on NO at the lower speed only. Am I looking at a new Catalytic converter
> do you think?
>
> Thanks for any ideas.
>
> Dan
>
My '90 Sentra failed the local emissions test one year. Per the mechanic who tested it, I:
- Changed oil & filter (Fram + Castrol Syntec Blend, but I'd use Mobil 1 now)
- Changed plugs (NGC)
- Changed fuel filter (Fram)
- Changed PCV valve
- Changed air filter (Fram)
- Week before I planned to test it, I put in Gumout Xtra Fuel Injector cleaner before I filled the tank, drove the tank down to E, then filled up again before the test.
Since then, the car ran great, and I did this every year before the inspection. Never failed the emissions test again!!!
Good luck!!
~Bhuvan