Hello ive got a 1992 honda civic vx, it hasnt passed etest in 5 years now it has a 1.5 d15z1 motor 400,000 km , on the test is fails with high HC ( high Hydrocarbon ) anyone have any idea on how to lower it ???

thanks

 

What causes high HC. What causes high Hydrocarbon - SmogTips.com. Failed HC Emissions. Why did my car fail the emission test for high HC emissions. What is HC. My vehicle failed the emission test for high Hydrocarbons. Why my car produced high HC. Hi

 

Is the Z1 the original VX engine type? The VX was a special setup and you can't mix parts from other models (e.g. the engine and ECU must match. It also used a special wideband oxygen sensor).

Overcooling the engine (thermostat stuck open or wrong thermostat) will cause the ECU to never enter closed loop mode, which means high emissions.

If you have a proper setup, no misfiring, and also elevated (higher than normal though not necessarily failing) CO and NOx, its likely that the catalytic converter is worn out and needs replacing.