1996 Toyota Corolla HC failed in smog test

1996 TOYOTA COROLLA
153,000 MILES • 4 CYL • FWD • AUTOMATIC
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PENGUIN
  • MEMBER
  • 3 POSTS
My 96 corolla failed for 15 mph test; HC max is 64 and measure is 69. Other readings are fine.

15 mph
HC (MAX-64, AVE-9, MEAS-69)
CO (MAX-0.55, AVE-0.02, MEAS-0.17)
NO (MAX-477, AVE-57, MEAS-190)

25 mph
HC (MAX-47, AVE-7, MEAS-39)
CO (MAX-0.54, AVE-0.03, MEAS-0.11)
NO (MAX-764, AVE-50, MEAS-130)

With 150K, the car is running as good as day 1. What could cause the high HC measure?

Any input will be appreciated
Jul 13, 2008 at 4:14 PM
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DOCHAGERTY
  • ✓Experienced Mechanic
  • 9,606 POSTS
As a smog technician myself, the reason the hydrocarbons are high is because the ignition system is not able to deliver an adequate spark either due to worn or improperly gapped spark plugs or to components that require replacement such as ignition wires or distributor cap/rotor.
Jul 13, 2008 at 6:28 PM
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