Skip the auto shop - Our mechanics make house calls

Q: Car idling up and down

asked by on

The car is idling up and down.

This is a common issue. My first instinct would be to look for a vacuum leak. Air going into the engine is metered so that the ECM knows how much fuel to add for a correct mixture. If you have a vacuum leak or unmetered air, both the mixture will be off, and the engine’s idle can race as it does with most vacuum leaks. The ECM will attempt to control this sometimes, which makes it erratic. Vacuum leaks can also happen in multiple places. I suggest seeking help from a qualified mechanic to verify this rough idle diagnosis.

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

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: I have a random misfire

Hi there. Typically the P-0300 error code indicates an electrical issue somewhere in the ignition system that causes a random misfire.. In most cases, it's caused by damage to the distributor, coil or a camshaft sensor. Before you spend more...

Q: My ABS & check engine light on My 1992 honda accord

Hi There, There are a number of things that may cause the car to hesitate when accelerating such as low fuel pressure, a dirty or faulty mass air flow sensor, clogged or dirty fuel injectors, a faulty throttle position sensor...

Q: Won't start

A number of faults can keep the vehicle from starting. Most commonly can be a lack of spark or lack of fuel. Lack of spark can be caused by anything from the crankshaft sensor not sending a signal to the...

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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.