Do You Know the Common Reasons for Engine Stalling Problems?
The problems associated with the engine are more often related to the temperature. And engine stalling mostly occurs during cold weather or when the engine is cold while starting. The main reason for stalling of the engine is the absence of sufficient fuel or the presence of too much air in the air-fuel mixture. It is noted that a cold engine needs a highly rich air-fuel mixture to start and to idle smoothly in order to warm up.
Such an issue is difficult to solve as there are several things that could be causing your engine to stall. In order to find the cause of the problem, you must have some working knowledge of the car's air, fuel and electrical systems. Generally, the engine stalling problems arise due to the following reasons.
The issues that evolve from an engine vacuum leak can be very frustrating. One of the problems that happens is the idle speed becomes way too fast and the engine starts to stall. The confirmation of an engine vacuum leak can be a very loud hissing sound coming from the engine area. Hesitation can come from accelerator problems but it also may be symptomatic of an engine vacuum leaks.
An EGR valve that fails to close at idle is another common cause of stalling. If the EGR valve is stuck open or can’t seat because of carbon buildup under the valve. As a result, it will allow too much exhaust to be sucked back into the intake manifold. This can make the engine idle rough, misfire and/or stall. Inspecting and cleaning the EGR valve and the EGR port in the intake manifold should cure the problem.
Excessively rich or lean idling
A sensor that has been contaminated by fuel, varnish or dirt wills under-report airflow. It will slow to react to changes in airflow as well. This can upset the air/fuel mixture causing idle, stalling and hesitation problems. Cleaning the airflow sensor wire with aerosol electronics cleaner can often restore normal operation and cure the problem.
If the engine stalls while idling or driving, the engine may be running out of fuel. This could be from not receiving enough fuel pressure to keep it running. The most likely cause of this kind of stalling would be a fuel pump that is not spinning fast enough or is intermittently cutting out. If the vehicle is more than seven or eight years old the fuel pump would certainly be suspect. But as with the idle speed control circuit, don’t replace anything until you’ve run some diagnostic tests. The first thing to check would be fuel pressure.
Defective idle speed control system
Idle speed on a fuel injected engine is controlled by allowing a small amount of air to bypass the throttle. The most common failure is partial/complete jamming of the actuator (due to dirt/dust or even oil). The result is that it cannot be smoothly controlled. If the idle air bypass circuit is clogged with dirt or fuel varnish or the solenoid valve is sticking or broken, the engine may not get enough air to idle normally causing it to stall. Cleaning the idle air bypass circuit in the throttle body with aerosol throttle cleaner will often remove the gunk and solve your stalling problem.
If the coolant sensor is bad and tells the PCM the engine is colder or warmer than it really is, that can confuse the fuel mixture results. A faulty sensor will often cause driving in cold and emission problems. If the coolant sensor reads colder than normal or cold all the time, the engine will run rich. This won’t cause cold stalling but it can make for a rough idle once the engine warms up. If the coolant sensor reads warmer than normal or reads hot all the time, the PCM will lean out the fuel mixture too much, causing the engine to stall when it is cold.
Faulty air temperature sensor
This sensor tells the PCM the temperature of the air entering the intake manifold. The IAT sensor can be damaged by backfiring of the engine. The sensor can also show faulty readings due to the accumulation of oil and carbon, wear and tear. Also a poor connection after servicing the air filter unit. The PCM needs an accurate input so it can balance the air/fuel mixture properly. Just like a bad coolant sensor, a bad air temperature sensor can upset the fuel mixture causing stalling problems.
