How to fix a rough idle or stalling car?

May 24, 2019 | Same topic: Handy maintenance tips
Handy guide and tips on how to identify the main problem of a rough idle or stalling car and step-by-step on how to fix it.

The car engine's idle is somewhat like the heartbeat of a human. You can easily tell if there are problems by just listening to it. There are different idle speed problems like fast idle, slow idle, idling for a few seconds then stalling and/or rough idle are signs that something’s wrong with the engine of a car.

When you notice the same thing with your vehicle, you should immediately inspect, diagnose, and repair it. There are repairs that can be done by the car owner alone, but more often, a professional mechanic is required to sort things out.

Philkotse.com will help you sort out repairs that you can do on your own. We gathered several tips on fixing rough idle or stalling car.

Rough idle can happen in different weather conditions and temperature. The repair will actually vary depending on the temperature and weather conditions you are in.

Rough Idle How to Fix - Engine Stalls at Stop Signs

I. Fix rough idle in the cold

Rough idle can happen during cold temperatures. For example, it is a cold day and you stopped at the stoplight. You press on the brake pedal to stop, however, the engine started to idle very roughly then stalls.

But when you start the engine once again and drive the vehicle at higher speed, it's running fine or more smoothly. If that's the case, then here is what could be wrong and how to fix it:

  • If your car has a carburetor, then you might have a faulty power circuit or accelerator pump. To fix this, you have to replace the carburetor or the accelerator pump.

carburetor

You might have a faulty power circuit or accelerator pump

  • There may be a possible vacuum leak. To fix this, you have to thoroughly inspect the vacuum lines to check if there is indeed a vacuum leak. If there is, you will need to replace the vacuum lines.
  • There might be some kind of problem in the ignition. You can fix this by inspecting and replacing the rotor, distributor cap, spark plugs, and ignition wires. Check each one of them and replace it if it’s faulty or broken.

Man holding the sparkplug

Inspect and replace the rotor, distributor cap, spark plugs, and ignition wires

  • It might be an incorrect setting of the ignition timing. To repair this, all you have to do is to adjust the ignition timing in the correct setting.

Ignition timing

It might be an incorrect setting of the ignition timing

  • The computerized engine control system might be faulty or broken. To fix this, you have to bring your vehicle to your dealership or mechanic to inspect and check the car’s engine control system using a scan tool. They will test the circuits and replace or repair the components if needed.
  • You might have a faulty or bad EGR valve which can be fixed by replacing the EGR valve.

Bad egr valve

Check your EGR valve regularly

  • There might be mechanical problems in the engine. You will be able to fix these by checking the compression. This will enable you to identify the condition of the engine.
  • It might be an incorrect setting of idle speed. You can fix it by setting the idle speed to the original setting of the vehicle. You may refer to the owner’s manual for this information or you can search for it online.
  • The problem can also be because of the dirty fuel injectors which can easily be repaired by cleaning and/or replacing the fuel injectors.

>>> Read more: Must-know tips to clean air throttle body & idle air control valve properly.

II. Fix rough idle with a warm engine

When you experience the same situation as what you did in the cold, but this time, the engine is hot or warm, then the problem might be the same. The only difference is that the fuel pressure regulator of the car might be operating at very low pressure.

So, to fix these, you have to check the pressure of the fuel using a fuel pressure gauge. If needed, you will also need to replace the fuel pressure regulator of the car. Just a reminder, this job is not really a DIY procedure, but it can still be done on your own if you’re an experienced home mechanic.

Fuel pressure

Check the pressure of the fuel using a fuel pressure gauge

III. Fast idling

There are instances that the engine has already run long enough for it to become warm, but the idle speed still doesn’t come down to normal and still continues to idle at a fast speed.

You will easily notice it when the vehicle come to halt. In which you’ll have to press hard on the brake pedal to prevent the vehicle from moving. If this is the case, here are the things that could happen aside from the ones given above:

  • Your car’s engine might be overheating. You can fix this by checking and repairing the cooling system of your vehicle.
  • Your vehicle has faulty or broken idle speed control unit which can only be fixed by replacing it.
  • The alternator of your car might be faulty. The only thing to fix this is to replace the alternator.

White smoke

If fast idling happens, your car’s engine might be overheating

IV. Staling upon stopping

When you’re driving and everything is fine but when you release the gas pedal to push the brakes, the engine starts to shake or even stall, the problem might be the following:

  • It can be a serious vacuum leak. Depending on the severity of the leak, the vacuum should be repaired or replaced for the problem to be fixed.

Man checking for vacuum leak

It can be a serious vacuum leak

  • The computerized engine control system of your car might be faulty or broken. If this is the case, you will need to bring your vehicle to the dealership or your trusted mechanic. As mentioned above, they will need to check and inspect the engine control system of the car with the use of a scan tool.
  • There can be a broken linkage which can be fixed by repairing or replacing the linkage depending on the damage.

>>> See also:

When you experience idling issues, it sure is frustrating. However, you’ll be able to figure it out if you have some patience when troubleshooting the root cause of the problem.

If you’re in doubt of your own ability to check and repair the car, then you should seek assistance from a professional mechanic. They will help you address the problem as well as identify and fix other potential car problems aside from the existing idle issues.

Source: Hanna Miel Sanchez