Troubleshooting a Hesitating Engine

Woman driver scared shocked before crash
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You know how frustrating it can be when your car hesitates when you step on the gas. Instead of get-up-and-go, you get hurry up and wait. But you can troubleshoot this common problem, maybe even fix it yourself. At the very least, you'll be able to give your mechanic a head start and save yourself the extra money it will cost for a diagnosis.

It's a No Go

It's Monday morning, and you're on your way to work in your trusty car and truck.

You're running a little late, but sitting in pole position at the last light before hitting your employee parking lot. So when the stoplight turns from red to green, you punch the gas pedal, hoping to sail through the intersection a little, um, faster than usual. 

But instead of moving when you hit the gas pedal, your car hesitates. Juuust long enough for every car behind you to honk, flip you the bird, or angrily swerve around you. They're sailing right on through. So why are you sitting there, bogged down, pumping the gas until your little engine that could finally muster enough power to come up to speed?

Causes of Engine Hesitation

The feeling is unmistakable. Your engine either seems to bog down when you hit the gas pedal, or it takes a second or two to respond. It's not quite a stutter, not quite a stall, and it doesn't matter if the engine is hot, cold, or low on gas. 

There are a number of possible causes, but you're going to have to take a good look at your engine to try and diagnose the problem.

You can do this by shutting off the engine, putting on some old clothes and gloves, and making sure nothing is dangling from your body that could get caught in a part of a cooling fan that suddenly decides to start running, even thought the engine is off.

An engine that hesitates when accelerating is either sucking too much air, not getting enough fuel, or misfiring.

Here's what you might discover—and what you can do to fix the problem:

  1. Dirty air filter.
    The Fix: Replace the air filter.
  2. The spark plugs may be dirty or worn.
    The Fix: Replace spark plugs.
  3. The ignition wires may be bad.
    The Fix: Inspect and replace ignition wires.
  4. Ignition system problems.
    The Fix: Check distributor cap or rotor. Ignition module may be bad.
  5. You may have water in the gasoline.
    The Fix: Drain the gas tank and flush with fresh gas and refill. (Generally not a DIY job)
  6. If you have a carburetor, you may have a bad accelerator pump or power circuit.
    The Fix: Replace accelerator pump or clean or replace the carburetort.
  7. The fuel filter may be clogged.
    The Fix: Replace the fuel filter.
  8. Your catalytic converter may be clogged.
    The Fix: Replace catalytic converter.

On-board Diagnostics

In a newer model car, the vehicle's computer diagnostic system is likely to tell you what's going on by flashing the Check Engine light on your dash. Then you just need to learn what the codes mean.