Engine Noises

You’ll only hear these when the engine is running.They also often change their pitch with the speed of the engine. So if you increase the speed of the engine and the noise changes along with it then it’s engine related. Knocking, ticking, screeching, and grinding are common types of engine related noises. Always ensure your vehicle has the proper amount of oil at all times. Engine noises should never be left unchecked.

Brake Noises

Squeaking, grinding and scraping are the most common types of brake noises. All three of these most likely mean it’s time for new brakes. Other reasons include the use of low quality parts or improper installation. A grinding or scraping noise can occur whether the brake pedal is applied or not. Squeaking generally only happens when the brakes are applied.

Suspension Noises

When you hear a clunk, pop or creek while going over road imperfections you can bet it’s suspension related. If your suspension is in good shape it will run quiet and smooth over bumps and dips. You will only hear suspension noises when the car is rolling because the suspension must travel through it’s range of motions. Worn bushings, steering linkages, ball joints are usually the culprit. While shocks and struts will cause excessive clunking when they are at the end of their life.

Tire Noises

Tire vibration and humming will only be heard when the vehicle is moving and usually at higher speeds. Unevenly worn tires can cause a constant loud humming while rolling at mid to high speed. This noise is not to be confused with a wheel bearing which has a similar sound, but changes in tone as you increase speed or shift weight onto the offending bearing. A vibration sound indicates your tires aren’t rolling correctly. A tire balancing or replacement and balance will take care of the vibration.

In Cabin Noises

Sometimes you will hear noises coming from behind the dash that make it sound like gremlins are living in there. There many moving parts to the heating and cool air system than you would think. Actuators that open and close vents eventually go bad causing annoying vibrations. Seats that are worn or otherwise not latched in all the way make sounds that can trick you into thinking you need suspension repairs.

Hopefully this guide helps give you a better understanding should you encounter anything and have to question whether or not to get it looked at. Keep in mind if you wait too long it could end up being extremely costly. As always the ASE certified professionals at MR Auto SD are here to help. Feel free to stop by or give us a call at (858) 455-8222.

 
When one or more of the cylinders are not producing power because there is a lack of detonation in that cylinder, that is known as a misfire. However in order to explain what a misfire is and what causes I will quickly explain how an basic engine works. For an engine to run properly it needs air, fuel, spark and compression. Think of each cylinder as a container. Air and fuel are injected into the cylinder through valves on the top of the engine, the piston moves up to compress the fuel and air mixture which is then ignited by a spark shooting the piston down with a big bang. Voila! You have power. The piston then comes back up to expel the burnt gases out. When you line up multiple cylinders and attach the pistons to one common crankshaft, all these detonations will make enough power to rotate the crankshaft.

Now let’s go over these four main components individually to see how they would inhibit combustion.

When the piston moves down it sucks air into the cylinder which travels from outside of the car through the air filter, into the intake manifold and finally into the engine. The amount of air is measured by an air mass or manifold absolute pressure sensor. If air is restricted (clogged air filter or inlet), unmetered air sneaks past the sensor (vacuum leak), or if the sensors themselves are defective it may cause a misfire.

Without fuel the engine simply will not run. So a fuel pump will only cause a misfire if it supplies enough pressure to start and run the car, but but fails to deliver enough fuel under load. In most cases fuel related misfires are due to a faulty fuel injector.

Compression requires the cylinder to be sealed air tight. After fuel and air are inducted, the piston compresses it into a dense mixture. If the cylinder isn’t airtight in any way after the valves close the mixture will leak out and will not combust. Leaking head gaskets, cracks in the cylinder head or block, worn piston rings etc.

Spark ignites the mixture. If the spark plugs are too worn, or the ignition wires or ignition coils have issues than it will not deliver the spark when it is needed.

Now that you know the basics you’ll have a better idea of what’s going on in your car if ever this should happen to you. But believe it or not misfires can actually be more complicated than this to diagnose. That’s when your friendly certified technicians at MR Auto SD come in handy. One last thing, all these cycles that occur in order for the engine to run have to be synchronized. So in the next installment we will cover engine timing. See you next time!