I was in here in the beginning of February with a 91 Civic, 222,000 miles,
and a failed emissions test. So I did the cheap stuff, oil change, tune up,
Still failed emissions.
I tried that guaranteed emissions passer stuff you put in your tank - no
dice. I think it actually elevated some of my totals. On a lark I added
"engine restorer" to the crankcase. I've never had any luck with these
types of oil additives. Like I said before, I was burning 1-2 quarts of oil
every 2 weeks or approx. every 700 miles. Since then I haven't burned any
oil! It's been about 3 weeks. I'm still pretty skeptical so I've been
checking my oil regularly but the additive actually seems to be working.
But it still wouldn't pass so I went to a "certified emissions repair
facility". They checked out my emissions and said it was the catalytic
converter. So $285 later I have a new cat and plan on getting tested again
next week. Driving home I did notice a lot less smoke coming from the
exhaust. Hopefully, that fixed the problem.
One thing the mechanic told me that I thought was pretty interesting: he
figured it was the cat because the oxides of nitrogen were highly elevated.
He said that EGR valves and catalytic converters are really the only things
that keep those levels in check. He also said that a failed cat may not
affect the car's performance at all, something I was unaware of. I guess
the performance is only affected if the cat is "plugged"?
Thanks to everyone for their help, especially Jason, Tegger, Jim Beam, and
Michael Pardee. I've learned a lot from this group!