March 4, 2021
Safety Talk - An Evil Cousin to Engine Knock

Safety Talk – An Evil Cousin to Engine Knock

If you have an older model vehicle that has been running for a long time the potential for engine knock is something that you have to worry about, but not worry so much that you can’t drive. Engine knock has been a fairly typical event in these older models and it can be caused by the spark timing changing and can be fixed with the use of new spark plugs and the right gasoline. Engine knock has been studied to the extent that it feels the same as your car getting a cold that will take just a bit of medicine to correct the issue.  You always want to know the safety status of your vehicle before you hit the road.

Unfortunately, with the widespread use of smaller turbocharged and direct injection engines of the modern era, we see a new phenomenon taking place that has yet to be explained. This event is called Low-Speed Pre-Ignition (LSPI) which is being studied extensively because there hasn’t been any explanation as to why this event takes place. Engine knock is easy to discern, typically this only happens when the engine is under an extremely high load and pressure, while LSPI takes place when the engine is operating at a much lower load rate.

What Happens When LSPI Occurs?

Because all engines that make use of turbocharging, supercharging, or any other form of direct injection are subject to the potential of LSPI, you should likely be concerned. We use these forms of injection to increase fuel mileage and horsepower while making use of smaller engines that produce lower emissions, but there is a potential for this forcing of the induction to cause the engine to nearly blow up under your hood. This explosion won’t be similar to car explosions in movies, but it could be just as damaging as the scene you see for your entertainment.

There have been reports of LSPI doing as much damage as causing parts of the piston to become lodged between the top of the piston and the cylinder head. LSPI leads to much higher cylinder pressure than a traditional engine knock and can cause piston tops to crack, rings to break, liners to become scuffed, and the cracking of the cylinder head can become possible as well. This is certainly the equivalent of a small bomb going off in your car and it can be done for if LSPI is something that happens under your hood.

Is This a Safety Issue?

Is this something you should be concerned about? Is it a safety issue? Maybe, but probably not. Even though engineers aren’t sure what causes LSPI, the conditions that take place that cause LSPI are being studied to learn when it occurs most often. By calibrating engines to avoid the conditions when LSPI is most likely to take place, your vehicle is not likely to experience this problem. With that said, there aren’t any guarantees. With new technology comes a new set of challenges and issues that can take place under the hood that will cause your vehicle to blow up and make it difficult for you to drive where you need to go. Hopefully, you never experience LSPI, but now you know what it is. Keep abreast of safety and tech issues on your vehicle so you can keep going on the road. When in doubt, visit your local dealer.