Vehicle shuts off intermittently at idle

vehicle shuts off intermittently at idol mostly when AC is on. rough erratic idol. codes p0113 and p0174. tried new MAF sensor and new idol control valve.

My car has 156000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
The P0113 code relates to a problem with the intake air temperature (IAT) sensor. The computer is seeing a reading that is outside of its normal parameters and is causing the computer to set the code. This could also be why the P0174 code is being set at the same time, as it has to do with the fuel strategy that the computer is trying to set for the engine being out of range, due to the information being received from the IAT.

There could be a faulty sensor, it may have come unplugged, there could be a wiring problem, or possibly a computer problem. Since there are so many variables, some further testing will be necessary if you are unable to find the fault visually. One of our mobile technicians will be happy to come to your location in order to diagnose these trouble codes further and make the necessary repairs to your car.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Most commonly when the car stalls while driving, but starts right up after, the cause is an intermittently failing crankshaft position sensor or camshaft position sensor. The first step to diagnosing this problem however, would be to scan the engine control module to check for fault codes.
A rough idle without any codes could be caused by various factors, such as vacuum leaks, a dirty throttle body, a malfunctioning idle air control valve, clogged fuel injectors, clogged air filters, poor quality fuel, or even a blown a fuse.
There are a range of reasons why your car is juddering when you accelerate. Your vehicle could have dirty fuel injectors, a damaged fuel pump, a blocked catalytic converter, a faulty mass airflow sensor, broken spark plugs, or even an accumulation of moisture.
Idling a car can cause carbon to build up on the spark plugs and inside the cylinder, which can in turn lead to a misfire or an underperforming spark situation. Either of these issues can lead to check engine lights.
A fault in the IAC such as build up, can cause poor idling or stalling of the engine. If not working properly, the engine may not cope with the loads produced by various systems in the car. More specifically, it may be too low to run the A/C and hence it stalls when turned on.
Among the potential underlying causes are vacuum leaks, EGR system malfunctions, malfunctioning oxygen sensors, dirty fuel injectors, fuel pump malfunction, faulty spark plugs, a faulty mass airflow sensor, or a faulty throttle position sensor.
Your car should not jerk around, surge forward, or stall when you apply the gas, and if it does, chances are that your engine is well on the way to failure. Performance issues always signal a deeper problem, and in this case, that problem can be worn out spark plugs, clogged fuel lines, or even failing pistons.
Engine Misfires

Perhaps the single most common cause of rough idle comes in the form of a misfiring engine. As you may know, any automotive engine contains multiple cylinders. Each of these cylinders contributes to powering your car by combusting a mixture of gasoline and air.

While some cases are less severe than others, a rough idle is usually identifiable by a shaking and bouncing sensation in the vehicle. You may also notice odd sounds, as well as inconsistent RPM counts. Normally, a vehicle should have a smooth and consistent RPM rate of around 1,000.
The most common reason is simply running out of gas. However, if you have a full tank of fuel, and your car still dies, then there is more to it than a lack of gas. You might have a clogged filter or a bad fuel pump, for example. Both of these issues prevent your engine from getting enough fuel.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

High idling, jumping while idling, idle air control valve code
ANSWER : Hi there. This can be caused by the issues that you mentioned or a number of other things. You need to make sure all of the connectors are making good contact. I would then need to know what codes are in the computer to know if this is a circuit issue or not. Most of the time, it is not the circuit but instead a vacuum leak.

If there is a vacuum leak, then the vehicle will act like this and the computer cannot control the idle. Most of the time it is a bad hose or an EGR valve that is stuck open. That is the most common cause for this. I typically remove the EGR to check it to feel the diaphragm on the bottom of it to see if it is moving correctly. If you need to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose and repair your car’s idling issue.

My ’98 expedition drives fine for a while, then after a few hours, when sitting still, it idles rough then shuts off.
ANSWER : After some testing done to verify the EGR valve flow to see if the valve is intermittently sticking open causing the stall. This can be done using a scanner with the capability to open and close the EGR valve and monitor the DPFE sensor at the same time. There is a technical service bulletin 05-4-17 to replace the EGR valve if the valve sticks open. The computer system should be retested to verify the proper operation of the EGR valve and DPFE sensor. Once the EGR valve is replaced and system is verified the EGR system is working correctly without the EGR sticking open anymore then have a certified technician, like one from YourMechanic, scan the computer to clear any codes. Once codes are cleared a road test should be done on the car to verify the repairs.

My ’98 expedition, it drives fine for a while, then after a few hours, when sitting still, it idles rough then shuts off.
ANSWER : After some testing done to verify the EGR valve flow to see if the valve is intermittently sticking open causing the stall. This can be done using a scanner with the capability to open and close the EGR valve and monitor the DPFE sensor at the same time. There is a technical service bulletin 05-4-17 to replace the EGR valve if the valve sticks open. The computer system should be retested to verify the proper operation of the EGR valve and DPFE sensor. Once the EGR valve is replaced and system is verified the EGR system is working correctly without the EGR sticking open anymore then scan the computer to clear any codes. Once codes are cleared then the car should be road tested to verify repairs. If you’d like to get this fixed, have a certified technician, such as one from YourMechanic, perform the necessary tests and properly diagnose your Check Engine Light firsthand.

Skipping engine, rough idle, shuts off during slow down & idle, overheating, white smoke from exhaust
ANSWER : Hi There,
It sounds like you may have a couple of separate issues going on here. Overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, a clogged radiator or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. You may also have a water pump that is beginning to fail. Water pumps often times will begin to produce a bit of a whining sound when they are starting to fail. A common problem also associated with this is the water pump may begin to leak around the water pump shaft due to the seal being damaged. In addition to leaking around the pump, you may have a leak elsewhere in the cooling system coming from one of the hoses going to or from the radiator.

The rough idle and shutting off at slow speeds may be caused by a dirty or faulty idle air control valve. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. This is also an important function when starting the motor as it allows the motor to run and idle on it’s own once the motor fires. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

While idling, the vehicle does not blow any hot air until the vehicle is moving.
ANSWER : This may suggest the thermostat is not opening and closing at the correct temperatures causing warm coolant to flow through the heater core. If this is the case, however you may also notice a fluctuation in engine temperature as well which as you know, may also cause overheating. I would recommend having an expert from YourMechanic come to your location to diagnose your heating system.

My car shut off while at a stoplight. I got it started only for it to shut off agin. It starts then shuts off.
ANSWER : Hello, thank you for writing in. The vehicle is stalling due to an electrical issue (typically pertaining to power supply or a sensor), a lack of fuel, or a failure with the ignition (spark) system. You will want to start by scanning the vehicle for diagnostic troubleshooting codes. Use any information found there to help guide you to the system or component that is failing. Without that information, you will want to test the fuel pump, ignition cables, spark plugs, and alternator function. Further testing may need to be done based on those results. For more help with diagnostics, contact our service department to schedule an appointment.

After replacing the power steering pump there was a low idle, idle screw is all out, running rich, and idle speed doesn’t change.
ANSWER : Hi there. The engine has a vacuum leak and is causing the engine to stumble down on the idle. Check all of the vacuum hoses and the brake booster for any leaks. The engine is rich for it’s not burning all of the fuel properly and may also have bad spark plugs. If you need further assistance with engine not adjusting the idle, then seek out a professional, such as one from Your Mechanic, to help you.

Car keeps idling down and shutting off when I drive it.
ANSWER : Hello there and thanks for writing in. Generally belts will squeak when they are loose or not aligned correctly. Occasionally, they may need to have a bit of belt dressing put on them to lubricate them. Your idle issue may likely be related to a dirty or faulty idle air control valve. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. This is also an important function when starting the motor as it allows the motor to run and idle on it’s own once the motor fires. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your idle air control valve.