Q: Engine idle fluctuates and dies.

asked by on

I was driving down the road and my truck started to bog down and tried to die. I pulled over pop the hood and looked around everything seemed fine..I started it up and it was bogging down trying to die.. I waited awhile and it fixed itself.. So on the road I went 20 minutes later it did it again.. I can start it up but I have to keep my foot on the pedal if not it will die..
My car has an automatic transmission.

This may be a couple of different things. Your truck has what is called a throttle position sensor. The throttle position sensor is a sensor used to monitor the throttle position of the throttle plate inside the throttle body in relation to your foot position on the gas pedal. Based upon the inputs from the sensor reading your foot’s position on the pedal, the ECU then makes the direction to supply more or less fuel to the motor. When this sensor is not working properly, this can cause intermittent responses when pressing the gas pedal.

Your truck’s engine also has what is called an idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. Since this valve is controlled by the vehicle’s computer, it 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. 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 truck.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Engine idle fluctuates and dies.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Ac condensation leaks a lot of water from drainage tube outside under yukon 2005, even if I haven't driven it in a day, is this ok

You will see varying amounts of condensation draining from the a/c drain depending how much humidity is in the truck. This is normal. The larger amount you see if just an indication of how much humid air is being removed...

Q: Intermittent and low speed wiper don't work fast speed wiper works 2014 Chevrolet Silverado 1500

Hi there - the lack of slow or intermittent motor speed can be caused by 2 issues: failure of the switches on the steering column stalk, or within the motor pulse control inside the motor housing. You're going to need...

Q: Car chugs when AC is on at a stoplight - 2005 Chrysler PT Cruiser

Hello - there may be a problem with your idle air control valve. Its job is to bump up engine idle when there is an additional load on the engine, such as the AC compressor. Other possibilities include a dirty...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...