When you hold your foot on the accelerator, does this condition go away? Do you have any enginge light on? Have you had any work done to your car recently? Sometimes a loose igntion wire can cause a "want to go dead' feeling.
Three things are needed to "make fire" in the engine: fuel, air, and spark. If any of these is interupted then it can sputter or just not run.
How those three gets there depends on the car. Older, carbureted engines mixed fuel and air in the carburetor and then moved them into the piston. Fuel interuptions would happen at the carburetor. Air interuptions rarely happened, but could be because of poor settings inside the carburetor.
In newer engines the air and fuel are brought in separately. A sticky fuel injector, low fuel pressure, or a computer problem can cause rough idling.
How the "spark" gets into the cylinder, via spark plug, has not changed much. What triggers the spark has. In older cars it could be a mechanical distributor/rotor/points system. If there were debris in there, or even poor spacing then the engine could rough-idle. In the newer systems its all computer controlled or hybrid.
It could have a weak or discharged battery. It could have a weak alternator/generator. It could have a clogged air or fuel filter.
There are a lot of things it can be. A quick inspection can tell a qualified mechanic what the problem is. How he goes about determining what the problem is and how to fix it really depends on the type of Car.
It could be something as simple as a fuel filter! Try that.
Then spark plugs and wires. Air filter.
If those check out fine or you have replaced them. Check for stored trouble codes or an illuminated CEL.
It could also be a Idle Air Controller problem, if they get dirty they can stick. Also, on computerized cars, crank and cam angle sensors can go bad. Lots of things here.
Judy 2/10/2011Sometimes when I stop at a red light I have to keep my foot on the gas peddle to keep it from going dead and even when I do that it still idles rough.
check your Idle Air Control Valve
An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or ECM (electronic control module) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. An IAC motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the IAC control motor to react slowly, either failure can cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak IAC motor. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed, also inspect the IAC for a build-up on the seating (pointed) end and clean as necessary.
An IAC motor is highly susceptible to carbon and coking build up; if an IAC goes too long without cleaning it can cause stalling and poor idle quality. Some cars are designed with a large vacuum transfer hose that connects the intake manifold to the IAC (idle air control) motor. If a broken or dilapidated these vacuum lines can cause the engine to lose vacuum which will allow the engine to run rough and die. Inspect all engine and accessory vacuum lines to look for missing, torn or dilapidated lines and replace as needed. Any car that is designed with a magnetic non-motor operated IAC like Toyota/Lexus is subject to carbon and should be cleaned about every 40,000 miles to avoid stalling.
To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed, also inspect the IAC for a build-up on the seating (pointed) end and clean as necessary
advance auto parts
BWD Idle Air Control Valve..........Part No. 50683 .................$141.99
Judy 2/10/2011Thank you so much for all your help.