CO | HC | POSSIBLE CAUSE |
HIgh | Normal | The gas-oil ratio is too high. |
Normal | High | 1. The ignition system is not in good condition Ignition timing is not correct Spark plug is clogged or its gap is not proper The platinum contact or the capacitor is not good. The ignition coil is not good Distributor cap or distributor is not good or electrically leaking 2. Valve timing is not properly adjusted 3. Exhaust valve is scratched |
Low | High | 1. Gasoline-air mixture is too thin, causing improper ignition 2. Vacuum leakage vacuum connector Intake manifold joint washer |
High | High | 1. The air filter is blocked 2.Carburetor is not good; idle mixture is rich; float is installed incorrectly; air choke is not functioning; strong valve is loosen; idle mixture screw or needle seat is scratched. 3.PCV valve is loosen |