When Your Car Won’t Start – Part 2

We have all had that sinking, sickening, aggravating feeling when we turn the key and nothing happens. Or we hear clicking, grinding, or other disturbing noises.  In any case, the issue is simply this: the car won’t start. In the last article, we mostly talked about weak batteries. In this article, we will focus on other reasons a car will not start. We will cover the essentials and then talk about the importance of air.


If you know the battery is good (or good enough), you can move on to other reasons why the car will not start.  There are a few key things to know about your engine to figure out what might be wrong. You must first understand what is needed to make the vehicle’s engine run.  The engine needs proper air, fuel, compression, spark, and exhaust.  As you may know, air is drawn into the engine in the intake phase. As the air is drawn in, it is mixed with fuel to create a highly combustible mixture. This mixture is compressed. At just the right moment, a spark is created to ignite the air/fuel mixture. This drives the piston down, and the spent fuel is expelled in the exhaust phase.

All of this needs to work together, and usually working perfectly, for the engine to run. This process is usually taken care of (in modern cars) via an onboard computer known as the ECU (engine control unit). So, yes, add in a computer to the mix of processes or parts that can go wrong.


Photo by Avi Richards on Unsplash

So, let us start with the air. If the engine does not get enough air, there is nothing to mix with the fuel, and therefore, no combustion. So, be sure to check and make sure there is a suitable amount of air getting into the engine.  I have actually seen vehicles (especially off-road ones) with completely clogged air intakes.  Check the air inlet and air filter to make sure the engine is getting the air it needs. I have heard some mechanics say if you hold the filter up to a light source or in the sun and can see the light coming through (not big holes), the filter is clean enough.

Your owner’s manual may have a diagram for the air filter. Or, you can take your car to a trusted mechanic and ask them to show you where the air intake is. Check online too.  Search for your vehicle make and model on the internet and check for helpful videos.

One thing to remember is you can never change your air filter too often.  If your vehicle could talk, it would most certainly thank you for a new, clean air filter.

Cleaning Air Filters

You can, theoretically, clean an air filter.  This is okay for your shop vacuum or home vacuum, but it is not recommended for vehicle engine air filters. Some people clean them by blowing compressed air in the opposite direction of normal air flow (from the inside out). However, the problem with this is that the air filter can be pierced by tiny debris. When you blow out the air filter, it leaves a tiny hole where the tiny debris was.  This can allow more debris to pass through and get into the engine. Therefore, I recommend a nice, fresh, new air filter.

Next Time

In the next article, we will discuss the importance of fuel. I know it seems like, “Duh, you need fuel,” but we will look into the potential causes for lack of fuel getting into the engine.

Written by Gary Pradel