If your car takes more than 4 seconds to start, you may have an issue you need to deal with. If it's extremely cold outside, this may be more of a common, weather-related issue and not much to worry about.
If the weather is no different from any other day when your car has started without issue, then you should troubleshoot the problem. Even though your car runs just fine today, it could take a turn for the worse and start giving you even more trouble if the issue is left alone.
Before you go inspecting the parts of your car, it's best to start by thinking about the situation you have when your car is difficult to start.
These can all give you invaluable clues. If any of these lights are on, it wouldn't hurt to get a free diagnostic from an auto parts store in your area.
If your car is slow to start, there could be any number of things wrong with it. Troubleshooting will take some time, so prepare for that. First, determine if the problem occurs when the car is hot, cold, or at all times. This will help narrow down where you should look.
Before anything else, look for signs of a leak. Ensure that all of your wiring is clean and without nicks or bites. An overly worn or chewed wire can easily cause this type of problem. The same can be said for hoses. Corroded connections can also cause a slow start.
Begin by checking the wires connected to your starter motor. These should be two of them and they should be thoroughly looked over for damage. The connections should also be tested to ensure that they are well-maintained and corrosion-free.
The starter motor itself should also be inspected for signs of wear. Too much wear may mean you need a new starter motor. If your car does run fine and there are no signs of leaks, smells, or bad wiring, but only the car struggles when starting, this could be your issue.
Next, move on to check your car battery and all of its connectors and wiring. Measure the health of your battery to make sure it isn't failing.
A bad car battery will make your car start slower and slower over time as it outputs less and less power. A battery over three years old should be tested at least once a year and this service will be offered free with an oil change at many shops (though you may have to ask for it.)
A battery with less than 70% of its original functionality is "failing" though it may continue to work "adequately" until it falls to 50% functionality. It will cause the car struggles to start.
Temperature and air flow sensors can begin to give bad readings if they are allowed to become dirty over time. This is a simple thing to fix. Locating the sensors may be the most difficult part but you should be able to do so with the help of your vehicle's manual.
After inspecting your wiring and hoses for damage or leaks, consider testing your fuel pump. This is done by placing the key in the car and turning it “on” but not so that the engine turns over. Turn it off. Repeat two more times and on the third try, turn the car all the way on so that the engine turns over. If it starts in 3 seconds or less, you've solved the problem for now. What you have, in this case, is a weak fuel pump that needs to be replaced.
Further, if it is very cold and you have a weak fuel pump, your car may completely refuse to start on the first try or two if the fuel supply is very low (below an eighth of a tank.)
In this case, adding fuel will allow the car to start “normally” again, but also reveals where your problems are most likely coming from.
One of the most overlooked causes of a slow start are clogged filters. This could be the oil or air filter. These both need regular servicing or replacement. Failing to do so can make it hard for your car to do what it needs to run, hence the slow start. This is a warning sign that if these filters remain dirty or clogged, things will begin to get worse or break down.
When it's cold out, your car will start slower than it normally would. Below certain temperatures, it may not start at all even if it's in great shape.
This is because your engine oil thickens up and your battery outputs less current. Your engine will also need more fuel to get going and stay going.
All of this adds up to a car that will not start quickly though isn't in need of repair. If, however, the problem persists when temperatures are well above freezing, you have a problem.
There are many, many things that could cause a slow start. The good news is that most of them are easy to troubleshoot on your own. However, if none of the above are the cause of your issue, you may need the help of a professional to find and fix the problem.
That said, if your car is running fine, the problem is likely to be small or localized. Further, all of the above steps should be done annually anyway, in order to keep your vehicle in good condition. The above troubleshooting options should help you locate the issue and give you peace of mind.