DavidK wrote:
> After having passed the California smog check for 2 tests (4 years) in a
> row, my stock '94 Del Sol ("S" model with 1.5L engine) failed today. :-(
> It's the first time I've ever had any car fail the Smog Check, in 20 years
> of living in California.
>
> I have never made any modifications to the engine, and I take it in for
> regular maintenance according to the maintenance schedule. It has been
> about 6500 miles since its last oil change, and I don't use any pour-in fuel
> additives. It is running normally with no noticeable engine problems.
>
> Here in California the DMV has recently made the Smog Check test more
> sophisticated, using a 'dynamometer' (treadmill) to test the car under load.
> They test the car at a simulated 15mph and at 25mph. They also added a NOX
> (nitrous oxide) emissions check, and that's the one that my car failed, but
> only at 15mph.
>

NOX is usually a function of the EGR valve, which your car might not
have. timing can also effect it, so id check that and replace the
plugs/plug wires/dist cap/rotor with OEM if necessary.

went through all that with a 1975 MG midget. by the time i got the EGR
unclogged, the smog pump working right, and a new $99 catalytic
converter on, it passed with flying colors. IIRC, some of the emissions
were *0*.

> As for my other emissions test results, my Del Sol had extremely low CO2,
> O2, HC and CO emissions at both 15mph and 25mph, but failed the Nitrous
> Oxide (NOX) test at 15mph. In fact, the NOX emission was about 3 times
> higher at 15mph than at 25mph, which seems counter-intuitive. I had driven
> the car at least 15 miles before arriving at the test facility, so it was
> well warmed-up.
>
> Has anyone else seen this kind of failure with an older Honda Civic or Del
> Sol? If so, what was the culprit? I'm trying to get an idea how much it's
> going to cost to have it fixed.

the O2 sensor is likely long overdue, if its never been replaced. a
place that ISNT "test only" should be able to pinpoint the exact problem.
>
> Thanks for any ideas, feedback, or sympathy. :-)
>
> -DK
>