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Showing posts with label Car Stalling Diagnostic. Show all posts
Showing posts with label Car Stalling Diagnostic. Show all posts
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Car Stalls at Idle

Generally speaking, car stalls at idle is an indication of a fuel problem specifically lack of fuel. Reasons which cause the car to stalls at idle are a bad idle air bypass valve, a bad cold start valve, or a bad fuel pressure regulator.

Reasons why car stalls at idle

1. Bad idle air bypass valve
2. Bad cold start valve
3. Bad fuel pressure regulator

What to do?
Quickly step on the gas pedal and observe if the engine will continue running. If the engine continues to run it means that the problem is a bad idle air bypass valve. Fuel injection car has a device called idle air bypass valve, the purpose of this device is to maintain the idle speed of the engine. If this device is not functioning properly then the engine will stall. When the gas pedal is depressed when the engine is about to stall is an indication of a bad idle air bypass valve. By stepping the gas pedal will increase the throttle which compensates for the bad idle air bypass valve giving the engine enough fuel to continue running.  Replace the bad idle air bypass valve to correct the problem.

However, if the engine will not continue running even when the gas pedal is depressed then it’s not a case of a bad idle air bypass valve.

Now, observe if the car stalls while driving happens only if the engine is cold but will not happen after the engine has warmed up then the problem is a bad cold start valve. Fuel injection car has a device called a cold start valve. The purpose of this device is to keep the engine running when the engine is cold by providing the engine more gas so that the engines have a rich air/fuel mixture. Replacing the bad cold start valve will fix the problem.

If the air bypass valve and the start valve is not the problem then the only remaining possible reason why your car stalls while idling is a bad fuel pressure regulator. Generally speaking, car stalls at idle is an indication of a fuel problem specifically lack of fuel. Fuel injection car has a fuel pressure regulator, the purpose of this device is to maintain the fuel pressure to each of every injector. If there is a problem with this device the engine will be deprived of fuel which will cause the car to stall. Replace the fuel pressure regulator to fix the problem.


Bring the car to a shop and ask the mechanic to verify the problem, if the problem is confirmed replace the defective parts as necessary.


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Why Does My Car Just Dies While Driving?

Why does my car just die while driving? Car runs then dies after several seconds. Lots of things can cause this kind of problem, the causes depend on the condition when the problem occurs. The engine will run on a few seconds then dies, this situation is called “Run On”. Run on makes the Engine dies when the engine is extremely hot.


The cause of the problem is extreme internal engine heat. When the engine temperature is too high any unburned fuel that is inside the combustion chamber will self-ignite and runs on occurs until all the unburned fuel is burned up.

What to do?
When this problem occurs there is nothing much you can do. However, using high octane gasoline can prevent this problem from happening because high octane gasoline tends to burn slowly and resist run on than the low octane gasoline. Also, bring the car to a shop and ask the mechanic to check the engine cooling system since the engine develops extremely high temperature that causes run on.

When engine idling speed is faster than normal

The most likely cause of the problem is fast idle speed Run On is also occurred when the idle speed is fast and when the idle speed is fast it means that the engine received fuel at a faster rate than normal. This cause unburned fuel remains inside the cylinder and will self-ignite when the engine is extremely hot and runs on until all the fuel is burned up. To fix the problem lower the idle speed, when your car is fuel injection the idle speed must be adjusted by a qualified person because it is a difficult job for a person with no knowledge on the system because usually it cannot be adjusted but rather you have to replace some parts in correcting the idle speed.

For a car with fuel injection system

This problem can cause by a leak on fuel injectors. Usually, this problem occurs on the fuel injection system when the fuel injectors are leaking.

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Supposed to be when the engine is shut off the fuel injectors is closed and prevents the fuel to leak out into the cylinder. If there is a leak, the fuel will self-ignite when the engine temperature is high thus run on occurs. Bring the car to shop and ask the mechanic to check the injectors for any leak. Replace the injectors to correct the problem.
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Car Stalling While Accelerating

The stalling occurs when the weather is cold wet morning. The possible reason for stalling is there is moisture on the distributor cap that causes the engine to misfire.


When the problem occurs on cold wet weather condition, usually this is because of the moisture on the distributor cap. The moisture forms inside the distributor cap when the car is parked overnight on a cold wet surrounding. The resulted moisture allows the electrical current to arc inside the distributor cap and causes misfiring of the engine and during acceleration arcing is become extreme which also cause the misfiring to become extreme enough to cause the engine stalling.

How to avoid condensation inside the distributor cap

Park the car inside the garage when rain is expected to pour. This will help prevent moisture accumulation inside the distributor cap.

If the stalling gradually becomes frequent during acceleration, the possible reason is that there is a possible vacuum leak.

Vacuum leak typically starts small and become worst as time goes by this is due to the pressure inside the engine. The vacuum created in the fuel system determines the amount of fuel an engine can get if there is a leak the air-fuel ratio of the engine will be out of specs and can cause the engine to hesitates and stall.

How to correct vacuum leak

Bring the car to a shop and ask the mechanic to check for the vacuum leak. Ask the mechanic to check the EGR and the PCV valves which is a very common source of a vacuum leak.

Car Stalling While Accelerating

If the car has fuel injection then the possible problem is a bad throttle position sensor. Throttle position sensor measures how far the driver has depressed the accelerator pedal. The data that the sensor detected will then be sent to the engine computer that makes the calculation. The result of the calculation will determine how much gas the fuel injection system should inject on the engine. When the sensor is bad the amount of gas to be injected into the engine will also be bad which may result is engine stalling when accelerating.
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Car Stalling While Driving

Car is stalling while driving. The stalling occurs when the engine temperature is high or even when the engine temperature is normal. The reason for this is because of vapor lock or a faulty fuel pressure regulator.


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