Skip the auto shop - Our mechanics make house calls

Q: Rough idling but car runs normal at high speeds. One plug cylinder well has oil seepage.

asked by on

My vehicle idling suddenly is rough and lower than the 1000 rpm but runs normal at higher speeds. Rough idle when stationary. Oil seepage in one spark plug well. Seems valve cover gasket needs to replaced. Is a change of spark plugs in order or a complete tune up and gasket change?

My car has 190000 miles.
My car has a manual transmission.

A: The rough idle may be caused by many differ...

The rough idle may be caused by many different things such as low fuel pressure, low voltage to the fuel injectors, dirty fuel injectors, a vacuum leak, a faulty Oxygen sensor or a dirty, or failing idle air control valve. Any of these possibilities relate to fuel delivery issues that will disrupt the normally balanced air/fuel mixture that would otherwise allow the motor to run smoothly. Dirty or failing spark plugs or wires may also cause a rough idle if they are causing one or more cylinders to misfire. I would recommend having an expert from YourMechanic come to your location to diagnose your rough idle problem.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: timing belt lifespan

The timing belt is recommended to be replaced at 105,000 miles. It should be inspected every three years if mileage is low. It may still get dry rot for excessive years.

Q: How do I control the air circulation?

The air circulation in your vehicle has two settings: recirculation (redistributing air throughout the vehicle), and outside air circulation (using air from outside the vehicle). To switch between the two, press the Air Recirculation button in the center of the...

Q: Car keeps idling down and shutting off when I drive it.

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...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.