It's not unusual for a car to begin hesitating on acceleration as it ages. This problem can come on gradually, so you may not even realize you have it until it becomes severe. Engine hesitation is not only annoying, it can be potentially dangerous if your car hesitates or stalls when you need to get out of the way of traffic. Therefore, it's important to identify and fix the problem as soon as possible.
Subtle signs of hesitation
You may have thought poor performance or hesitation was a result of the type of car your drive, and you did not realize that there was a problem which can be fixed or improved. One easily overlooked hesitation sign is that the car seems really slow when you start out at a complete stop. The car may seem to drag and then suddenly pick up after a short time. Another sign is when you turn the corner, you car seems to lose power before picking up again and running normally. Eventually, these issues will turn into complete hesitation where the car almost seems to stall.
Common causes of hesitation
Generally, hesitation is caused by problems in the fuel delivery system usually resulting in a lean mixture. Most likely, the problem is in the fuel injectors or fuel pump where things can get dirty and clogged making it hard for fuel to pass through. Cars with carburetors can also experience similar problems for similar reasons, except instead of dirty injectors, they may have dirty ports or cracked gaskets. Your fuel mixture can also be running lean because your car's sensors are faulty and giving your car's computer a false reading. Leaks in the system can cause pressure-related problems which affect the amount of fuel that actually gets through the injectors.
When you take your car to the mechanic, they will check for certain codes which could reveal if there's a bad sensor or a problem with any particular component. For most people, a couple of thorough fuel system cleanings can improve or solve the problem. Your car may also have a fuel filter which needs regular replacement. Some cars have filters inside the tank and only need to be replaced if there's a problem. If cleaning doesn't solve the problem, then your mechanic may look at replacing that in-tank sensor and possibly the fuel pump.
Engine hesitation is not something you should ignore as your car can cut out or stall at a dangerous time. These problems often come on gradually, so it's important to have them addressed as soon as you notice your car acting under-powered or hesitating, even if it seems minor. If your car is hesitating, or your check-engine light is on, contact your mechanic to see if your car's hesitation problem can be fixed.