You’ve inserted the key expecting it to turn over and run smoothly instead your vehicle immediately dies. The frustrating part is that it most likely can be caused by several things, leaving you confused.
This sudden stall after your vehicle turns over and fires up is very frustrating and could indicate many issues. Continue reading to learn what causes a car to start and then die or die soon after.
What Causes a Car That Starts but Won’t Stay Running?
There are many possible reasons why a car can stall immediately after startup. To get your car back on the road in as few minutes as possible, determining the cause is the first step.
Here are some of the more common reasons why your car won’t stay running.
#1. Anti-Theft System Issues.
The anti-theft system in one of many cars on the road today disables one or more of the engine’s systems to deter criminals from stealing your vehicle.
However, an issue with the system in your car, such as a transponder or key-chip failure, can also immobilize your vehicle in the same way.
Often, anti-theft systems in cars will stall a vehicle shortly after startup. This happens quickly when the anti-theft system cuts power to the fuel pump.
That is why a car will often stutter and die. In most cases, anti-theft failures reveal a key icon on the instrument cluster after the issue.
#2. Major Leak in Vacuum System.
While an engine is running, a natural negative pressure, or vacuum, is created in the intake manifold. The vacuum is created as the individual cylinders pull air into their respective combustion chambers as they cycle through their intake stroke.
The amount of air that goes into the intake manifold of the engine is controlled through the throttle body.
However, there are specific leaks in the intake tract of your vehicle, otherwise known as a vacuum leak, that can allow uncontrolled amounts of air into the engine.
A vacuum leak allows more air into the engine without changing the order or volume of fuel sprayed into the air-fuel ratio More air is still allowed into the intake, creating a lean condition, which could cause the vehicle to stall, especially when there is a serious leak.
#3. Mass Air Flow Sensor Issues.
The mass air flow (MAF) sensor determines how much air enters the engine intake. This amount is especially important in determining the amount of fuel injected into the engine and how engine fuel trims are calculated.
The MAF sensor data is critical in determining how to provide the proper amount of air to the fuel supply as efficiently as possible, placing great importance on the MAF’s operation.
However, MAFs can fail occasionally, sending faulty or irrational data to the ECM. The MAF itself could also be dirty, accomplishing the same purpose related to inaccurate readings.
When a MAF fails in either of these ways, the amount of air/fuel provided to the engine will not be accurate or regular, leading to a stall.
#4. Faulty Idle Air Control Valve.
An idle air control valve is used to control intake air flow at idle since the engine’s throttle plate is closed. A malfunction in the valve can create a number of issues, including shakes and misses at idle. In a worst-case scenario, it can cause an engine to stall altogether.
To be clear, the stalling that is caused by the idle air control valve usually takes place while an engine’s A/C compressor is engaged, or as other accessories are turned on. That is because the idle air control valve modulates the RPM changes when idling.
#5. Inoperable EGR Valve.
As of today, all vehicles are designed to meet emissions requirements imposed by the federal government, with the use of specialized equipment designed to minimize harmful exhaust emissions.
One such piece of equipment is the EGR valve, which transfers exhaust gas pollutants through the engine’s intake manifold. Exhaust gas pollutants are then reintroduced into the engine’s cylinders for combustion.
EGR valves also break. EGR valves break in a way that messes up how the exhaust gas pollutants are recycled. Instead of the exhaust gas pollutants recirculating only when an engine is warm, a broken EGR valve will allow exhaust gas pollutants to recirculate when the engine is cool.
An EGR valve could become stuck from carbon fouling and cause the same problem. In this event, stalling of the engine state can often follow.
#6. Ignition System Problems.
For an engine to run, the ignition system has to be properly functioning.
In some situations, defective components of an ignition system may prevent a vehicle from starting. Or can stall a vehicle at some point, including within seconds of start-up.
Since the ignition system is responsible for providing the spark for combustion, ignition problems can also create a stalling condition for a vehicle.
An ignition-related stalling condition could be caused by a few issues with the vehicle’s battery, battery terminals, ignition coil, ignition switch, spark plugs, or plug wires.
Additionally, ignition systems can also stall or, at the very least, create an extremely rough idle when multiple components, including spark plugs or coil-pack are all faulty.
#7. Fuel System Problems.
The fuel system of an engine is a critical part of the overall health of the engine. Without a properly functioning fuel system, many issues could happen based on the fuel system, one of which is stalling.
This is because proper fuel delivery is an ingredient of combustion, and we know that delivering lower amounts of fuel will equal lower performance in every case.
There are a number of fuel system issues that may cause a malfunction. Some common individual fuel system issues include a weak fuel pump, a failed fuel pump relay, bad injectors, and a failed regulator.
Older vehicles will experience similar issues when dealing with carburetor problems. Regardless, fuel system issues like these need to be confirmed and addressed with a fuel pressure gauge.
Why won’t my car stay running without giving it gas?
A common complaint from drivers is that their vehicle will not stay running unless they press on the gas pedal.
There could be several issues causing this, all of which have different severities. Regardless, the driver needs to figure out what is wrong with their vehicle to make the repairs they need.
One reason for this could be a faulty idle air control valve. Since the idle air control valve meters airflow through an engine’s intake at idle, even a minor problem can create a stall, where no throttle is needed.
However, pressing on a vehicle’s gas pedal actuates the engine’s throttle plate, effectively bypassing the air idle control valve.
Another possible reason for problems like this involves restricted fuel flow. When an engine is fuel-starved by a clogged fuel filter or any other kind of undesirable condition, it may require continuous throttle application.
This is common with carbureted applications. In some cases, a serious vacuum leak could create an engine stall that can be overcome via throttle application.
Pressing on your vehicle’s gas pedal gives variations in the engine’s air-to-fuel ratio, and therefore overcomes an imminent stall.