Rough Idle
A rough idle — shaking, uneven RPM, or stalling at stoplights — usually means the engine is not burning fuel evenly at low speed. It may feel fine on the highway, which makes it easy to put off — but misfires waste fuel and can damage the catalytic converter.
Symptoms
- Shake you feel in the seat or steering wheel at idle
- RPM needle bouncing or dipping toward stall
- Check engine light with misfire codes
- Worse when cold, better when warm — or the other way around
- Rough right after filling with gas
Can I keep driving with a rough idle?
Mild roughness with no warning lights — schedule diagnosis soon and avoid long idling.
Active misfire — flashing check engine light or hard shaking — drive gently to the shop or stop if it gets worse under load.
Stalling in traffic is a safety problem. Do not put it off.
Common causes
- Ignition misfire — spark plugs, coils, or wires
- Vacuum leak — extra air the computer did not meter
- Dirty throttle body or idle air control issue
- Fuel trim problems — injector, regulator, or sensor
- Worn engine mount — shake at idle, less under load
What happens next when you bring it in?
- 1 Call us. Tell us cold vs. hot behavior and any recent fuel or service work.
- 2 We review live fuel trim and misfire counters — not just stored codes.
- 3 We find the real problem first. You get a clear estimate before we do any repairs.
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