There are four main problems which could have caused your 1989 Toyota Camry
to fail for high HC, and more then likely you will need a smog check repair
shop to diagnose them. Hydrocarbon (HC) is basically raw fuel (gasoline).
High HC is usually caused due to poor fuel ignition. However since you've
already repaired your Toyota Camry's ignition system (spark plugs, cap,
rotor, spark plug wires) we'll focus on some other problems.
1. Improper Ignition Timing - We know you replaced the engine ignition
components but we just want to make sure you set the timing properly as
well.
2. Lean Fuel Mixture - Any condition which will cause unmetered air or not
enough fuel to enter your 1989 Toyota Camry's intake manifold will cause
high hydrocarbons (HC). This condition is called a lean misfire. You should
check that your Toyota Camry does not have any vacuum leaks and gasket leaks
which will cause more air to enter the combustion chambers then needed for
proper air to fuel ratio. You also want to make sure your Toyota Camry's
oxygen sensor is working properly and sending the correct signals to the ECU
(engine control computer) in order for the ECU to send the correct amount of
fuel to the engine.
3. Defective Catalytic Converter - If your Toyota's catalytic converter
(CAT) is damaged it will cause high emissions in all three areas (HC, CO,
and NO) emissions. Your Toyota Camry's CAT is designed to continue exhaust
combustion after the exhaust has left the engine.
4. Low Cylinder Compression - A compression test should be done to ensure
your Toyota Camry does not have a low compression problem. Reasons your
Camry's engine may have low compression in one or more of its engine
cylinders may include things such as burned intake or exhaust valve/s, worn
out piston rings, and in the worst case scenario, a burned head gasket.
