Why Is My Car Slow To Start?

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It’s a letdown when you jump into your car and try to start it and it begrudgingly turns over slowly. It cranks a few times and you wonder if it will start if you give it a few more tries. Of course, this always happens when you’re already late, it’s cold out, or your other car is broken down. But why is your car slow to start?

Table of Contents

Does your car struggle to start? Here’s reasons why your car might be slow to start.

Bad wiring
Worn starter
Charging system problems
Bad battery

Bad wiring

Your starter requires 2 wires to run properly. The large wire runs straight from your battery and always supplies power to your starter. The other smaller wire is a signal from when you turn your key telling the starter to engage and use all that power that is available from the battery. If either of those wires are making a poor connection or have become broken or corroded they could be giving a weak signal or insufficient power for your car to start. Sometimes this issue makes your car hard to start but runs fine once it gets going. If that is the case you can try replacing the wires or cleaning the connections.

Worn Starter

You may also have a slow to start car due to a worn starter, a common issue that will give you trouble, namely that your car won’t turn over. When you turn your key, an electromagnet forces the starter gear to engage the teeth on your flywheel. The motion of the starter gear sliding forward into the flywheel also engages electrical contacts which give power to the starter motor, spinning the starter gear and starting your engine. For more information on how your start works, check out this article about how a starter works. The electrical contacts that power the starter motor can wear out over time due to the high current flowing through them and the spinning motion of the starter motor. As these contacts wear down, they will transfer less and less power to your starter motor causing it to spin slower, making your vehicle harder to start. In this case, when your car won’t turn over, you may need a new starter for your vehicle to solve the problem.

Charging system problems

We’ve already talked about how your starter gets its power from your car’s battery but your car’s battery gets its power from your vehicle’s charging system. If your vehicle isn’t properly charging the battery either due to a bad alternator or bad control electronics your battery may be in good condition but slowly loses charge to the point where it can’t power the starter. When your engine is running your alternator should be producing between 13.5 and 14.5 volts which you can test at your battery terminals. If that voltage is lower you may have a problem with your charging system.

Bad Battery

The other most common reason you would have a car slow to start is that your car has a weak battery and it’s in need of replacement. The battery in your vehicle uses a chemical reaction between lead and sulfuric acid to create the electricity used to start your vehicle and to power the lights and accessories when your vehicle is not running. This chemical reaction between the lead and sulfuric acid creates a certain amount of current, and the bigger the battery, the more current it can produce. Automotive batteries are rated in “Cold Cranking Amps”. The higher the rating, the more power the battery can produce. If a battery is rated for 700 cold cranking amps (CCA), that means the chemical reaction inside can produce 700 amps for 30 seconds when it is 0oF. Over time, the constant charging and discharging of a battery will take a toll on the lead plates inside, causing them to corrode and the chemical reaction to become less effective. Temperature also affects the rate of the chemical reaction in a battery so a worm battery is more noticeable when it is cold outside.

As your battery wears out, it will produce less and less power for your starter motor to use, causing it to spin slower and causing your car to have trouble starting. You can measure the life of your battery by measuring the current it puts out while you are trying to start your vehicle. Measuring the current output of your battery takes a special tool, but is relatively simple to do. Many auto parts stores have the proper equipment and will measure your battery output for free. The same tool can test how well your starter and alternator are functioning as well, and often can all be done at the same time. Getting these tests done can be a great way to check up on your vehicle’s electrical system. You often will get a reading for your battery’s percent functionality and if it is below 70%, we recommend getting your battery replaced. Your vehicle may still start with your battery as low as 50% but at that level, it may also leave you stranded on a cold day.

If you’re having other starting problems, we’d like to help out with that too!

Why is My Car Cranking but not Starting?

If your engine will turn over but just won’t start you could have a few different problems. To start, your engine needs the right amount of fuel, a spark at the right time and air to mix with the fuel. Unless you’ve got an animal’s nest in your intake piping, it’s very unlikely that your engine isn’t getting enough air. On modern cars the computer controls when to spark happens. The computer uses a crankshaft position sensor, camshaft position sensor, or both to determine the right spark timing so you can check to make sure both of those sensors are working properly and talking to the computer by checking your engine computer for fault codes. To have a good spark you also need good ignition coils and a good spark plug so it can be worth checking those as well. If you’re sure you’ve got spark, next you can check fuel. The first place to start is checking your fuel pressure. Fuel injector cars usually have between 35 and 55 PSI of fuel pressure at the fuel rail. Low pressure can mean a failed fuel pump or failed pressure regulator and high fuel pressure can mean a bad regulator or a kinked line. If you have all these things it may be worth checking your vehicle’s computer to make sure it’s working correctly as well.

Why Does it Take Longer for my Car to Start When it’s Cold?

Cold starts are the most difficult time for an engine to get running. When it gets cold out, your engine oil thickens up making it hard to pump and taking more work for your engine to turn. Also, when it’s cold your engine’s battery produces less current for the starter motor so your engine doesn’t spin quite as fast as it would on a warm day. Lastly, a cold engine takes more fuel to start and run so it often takes a few more quirts of your injectors to get enough fuel to actually allow combustion to happen for the first time.

Why Does my Car Sometimes Fail to Start?

When your engine is warm and running normally it has lots of sensors to help determine the right ignition timing and fuel to keep it running smoothly. When your engine is first started, these sensors can’t help for a few seconds so the computer makes an educated guess at what the engine needs to run. Even in the newest cars, this guess can be a little skewed and your car may fail to start right away. If your car regularly fails to start, then it may be time for a tune-up! In today’s fuel injector cars tune-ups consist of changing your spark plugs, fuel filter, and engine air filter to help keep things running and starting properly. For more information on a tune-up for your car, check out our article on tune-ups!

If your car hesitates to start or starts slow, consider stopping by one of our partnering local auto parts stores to have your vehicle’s battery and starter tested. While you are getting your vehicle tested, check out BlueDevil’s full line of leak stop products guaranteed to stop your vehicle’s leaks!