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95 Honda Civic Emissions Testing Problem

I’ve got this 95 Honda Civic that was sitting for a couple of months until I took it to DEQ (emissions testing) where it failed due to high levels of hydrocarbons, but just barely. The attendant suggested driving it around a bit and bringing it back so I drove it all weekend, brought it back, and it did worse. So I changed the spark plugs and used a fuel injector cleaner, drove it around some more, took it back, and it did worse still. Anyone know what the problem is or how to fix it? (I’m running out of time with my trip permit to get it fixed so any answers are greatly appreciated.)

I have a Corolla of similar vintage and it has the same problem, close to the limit on HC’s during emission testing. I think the limit here is 130, and my car gets 135-140 when it fails, & like 127 when it finally passes.

When mine won’t pass here’s what I do

  • new spark plugs
  • new distributor cap/rotor/plug wires
  • change engine oil and filter
  • replace engine air filter
  • fuel injector cleaner treatment (the kind you put in the gas tank, but make sure it is all gone by time of test)
  • retard idle ignition timing by 2 degrees (compared to fsm spec)
  • check for any obvious vacuum and exhaust leaks
  • make sure idle rpm is at spec
  • make sure engine coolant temp is at spec
  • check valve clearances and adjust if required

If you search here for something like Corolla high emissions or high HC or something like that you’ll probably find the thread where the experts here guided me through the process. Sometimes you can find it faster by using google to find this Car Talk thread , so try that too. High HC’s are a common thing on Corollas so apparently it gets a lot of hits on google. . Best of luck.


Is your car burning a lot of oil?

How many miles on it? Can you detect any misfire or roughness in the engine? During the test, do they run the car on a dyno?