Emissions Test
 

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

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.