How to Adjust Overly Advanced Ignition Timing?
2 Answers
Adjusting the ignition timing involves calibrating and correcting the ignition moment when installing the distributor onto the engine, ensuring the high-voltage spark from the ignition system ignites the air-fuel mixture in the cylinder precisely. During engine operation, loosen the distributor's fixing screw. If ignition occurs too early, rotate the distributor housing in the direction of the distributor shaft rotation; if ignition is too late, rotate the housing in the opposite direction. When adjusting the ignition advance angle, perform the following checks: 1. On-vehicle ignition timing check: With the engine at normal operating temperature (70~80°C) and idling, suddenly accelerate. If the engine speed increases rapidly accompanied by brief and slight detonation (mild knock) that quickly disappears, the ignition timing is accurate. If the engine speed does not increase with throttle opening, the engine feels sluggish, and the exhaust emits a "popping" sound, ignition is too late. If the engine produces severe metallic knocking, i.e., detonation (knocking), ignition is too early. 2. Using an ignition timing light: Locate and verify the top dead center (TDC) mark for cylinder 1 at the end of compression and the ignition advance angle mark on the flywheel or front crankshaft pulley. Clean these marks to ensure visibility. If marks are unclear, highlight them with chalk or paint for better identification.
When the ignition timing is too advanced, the engine is prone to knocking, overheating, and a drop in power. I often adjust this when tinkering with engines. The first step is to use a timing light to align with the flywheel marks and check the current ignition angle; if it's more than five degrees earlier than the manual specifies, it needs adjustment. For older cars, locate the distributor base and slowly rotate the bolt to retard the ignition, having a friend start the engine to assist with observation during the operation. Modern cars are simpler—just connect an OBD scanner to the diagnostic port, access the ECU settings to adjust the timing parameters, reset, and then test drive a few dozen meters to check for any abnormal noises. Be sure to inspect the spark plugs and crankshaft sensor for proper function, as faults here could mislead adjustments. Take care not to turn the wrong components during the process, and after adjustment, clear any fault codes to ensure no residual issues, ensuring the engine runs smoothly and efficiently.
