Stalling and rough idle
Car Stalls, Idles Rough or Loses Power
A car that stalls, shakes at idle or loses power is often short of fuel, spark or air, or getting bad sensor information. Worn spark plugs, a weak fuel pump, a vacuum leak and a failing sensor can all do it.
- All makes and models
- $125 diagnostic, credited if you go ahead with the repair
- Nephi to Ogden, including Eagle Mountain and Heber
Why does my car stall or idle rough?
An engine needs fuel, spark, air and the right information from its sensors. A fault in any one can cause rough running.
- Ignition. Worn spark plugs, failing coils or damaged wires can cause a misfire. You feel it as a shake at idle or a hesitation.
- Fuel. A weak fuel pump, a clogged fuel filter or dirty injectors can starve the engine. It may stall under load or at speed.
- Air. A dirty air filter can restrict airflow, a vacuum leak can upset the air mix and a dirty throttle body can disturb the idle.
- Sensors. Air flow, oxygen and other sensors tell the computer how to run the engine. A failing sensor can cause stalling or poor power.
- Other causes. A failing alternator or a poor battery connection can also cause stalling.
How can I tell the causes apart?
The pattern helps. A shake at idle that smooths out when you rev often points to a vacuum leak or idle air problem. Stalling or loss of power under load, such as climbing a hill, leans toward fuel. A check engine light that comes on with the problem means the car stored a fault.
These are tendencies, not answers. Several causes can look alike, which is why guessing at parts is a poor plan.
Is it safe to keep driving a car that stalls?
No, not if it stalls while moving. A stall can cut power steering and brake assist. The wheel and pedal still work but take much more effort. Stop driving it until it is repaired.
Having it diagnosed
Call or text and describe the problem. The diagnostic visit is $125 on every job. If you go ahead, the $125 is credited toward the repair. When the repair is declined, the $125 is not refunded. A travel fee of $75 to $100 in addition to the diagnostic applies, depending on miles and fuel.
Questions
Questions about stalling and rough idle
Why does my car shake when idling?
It can be a misfire from worn spark plugs, a weak ignition coil or a bad plug wire. A vacuum leak, a dirty throttle body or a failing sensor can also cause it. The stored codes are a starting point, not a final answer.
Why does my car stall when I stop?
A dirty throttle body, a vacuum leak, a faulty idle control part or a failing sensor can cause it, and so can a weak fuel supply. It takes a diagnostic to look for which one it is.
Can bad spark plugs cause a car to stall?
Worn plugs can cause misfires, which make the engine run rough, hesitate and lose power. A severe misfire can contribute to stalling. Plugs are one of several possible causes, so a rough-running car is not automatically a plug problem.
Can a failing fuel pump cause stalling?
Yes. A weak fuel pump may not deliver enough fuel, especially under load, so the engine hesitates, loses power or stalls. On many newer cars the fuel filter is part of the in-tank pump, and on others a clogged filter can look similar.
Car stalling or running rough?
Give the year, make and model and when it stalls or shakes.