Engine spark knock, sounds like a metallic knocking, pinging or rattling noise, coming from your engine.
Engine Spark knock is often heard during engine acceleration, from moderate to heavy.
It usually happens when the engine is at or near its normal operating temperature.
Engine Spark knock is similar to pre-ignition but it is essentially an erratic type of combustion.
Engine Spark knock is caused by too much compression heat, or both. So, if your engine is making that annoying knocking, pinging or rattling sound; then you’re probably experiencing engine spark.
Abnormal combustion can result when the combustion chamber pressures are too high. This could eventually lead to a blown headgasket, broken rings or cracked piston lands, and/or flatten rod bearings.
What Are The Other Causes Of, Engine Spark Knock:
- Faulty (EGR) Valve
- Knock Sensor Failure
- Excessive Carbon Buildup
- Vacuum Leaks
- Higher That Normal Compression
- Exhaust Back Pressure
- Substandard Fuel
- Excessive Engine Temperatures
Faulty EGR Valve
When the engine is accelerating or lugging under load, the (EGR) valve should open. This allows some of the exhaust to enter the (EGR). valve, which will dilute the mixture. This reduces combustion temperatures and prevents knock. You should inspect the EGR valve’s operation and look for carbon deposits. If the carbon deposits are not being removed, you can either clean them off or replace the (EGR). valve.
Knock Sensor (KS) Detects Engine Spark Knock
Your engine has a knock sensor that detects this noise; and tells the computer to retard the ignition timing. Engine Spark knock is caused by the engine working hard under load. The (PCM) may retard timing. This will reduce your engine’s power, but it also protects it from any damage. Spark timing won’t slow down if the knock sensor doesn’t work. If the knock sensor is not working, spark timing will not retard when it should. You might hear a pinging, rattling, or acceleration sound when driving uphill or engine is lugging.
One way to check it is to tap on the engine near its sensor. Next, use a scanner to check the spark timing and/or knock sensor input. It is important to check if the timing retard signal is sent.
NOTE: Over advanced ignition timing, can also cause the same thing. The engine computer controls ignition timing. As a result, ignition timing, is not adjustable on today’s engines. Flash-reprogramming the (PCM), is the only way you can change the timing advance.
Excessive Carbon Buildup:
- Older high mileage engines
- Vehicles that never fully warm
- Only driven short distances
Treating your engine with a carbon cleaner or a fuel system additive, can usually clears this up.
Vacuum Leaks
Vehicle emission systems, may use vacuum to operate switches, solenoids and actuators around the engine:
- (EGR) valve
- (MAP) sensor
- (PCV) valve
- Purge valve
Vacuum leaks in any of these components, may cause knocking or pinging. Vacuum hoses can be damaged or disconnected.
Higher That Normal Compression
One cause could be an engine that has had, the cylinders bored oversize. This can increase the engine’s static compression ratio. Another option is a resurfaced cylinder head to restore flatness. This will reduce the volume of the combustion chamber and also; increase the engine’s static compression ratio.
These modifications will increase the engine’s power, but also increase the chance of spark knock when using regular 87 octane gasoline. Supercharged and turbocharged engines are at greater risk. The forced air induction system causes increased compression.
Exhaust Back Pressure
High back pressure is a common exhaust system problem. This could happen due to a blocked exhaust pipe, catalytic convertor or muffler. A clogged converter is the main cause of exhaust backpressure buildup. This will reduce engine airflow and cause the engine to heat up, losing power and run hotter. It can also cause knocking or pinging. Catalytic converters can clog due to fuel contamination or old age.
Substandard Fuel
Regular grade gasoline is supposed to have, an octane rating of 87 but, is not always the case. You can fix this by using premium or mid-range gasoline. Premium gasoline is more expensive, but it may reduce the cost of your gas. OrIf you buy gas at the same station every time, it is worth looking for another station. Don’t buy, the cheapest gas you can find.
Any of these could cause engine spark knock:
- Excessive Engine Temperatures
- Engine running too hot because of low coolant
- Cooling fan that isn’t working
- Plugged radiator
- Bad water pump
- Sticking thermostat
Conclusion
Finally, engine spark knock occurs when; excessive heat and pressure cause the air/fuel mixture to auto ignite. This creates multiple flame fronts in the combustion chamber and not one. These multiple flames collide with explosive force, which causes a sudden increase in cylinder pressure. A sharp metallic pinging, or engine knocking sound is also heard.
Thank you!
