Skip the auto shop - Our mechanics make house calls

Q: idles rough-worse with a/c on

asked by on

car runs well but idles poorly coming back to idle after stopping, condition worse with a/c on.well maintained, all emission and electronic engine controls still original.have checked for vacumn leaks and all is well-i think!

My car has 100000 miles.
My car has an automatic transmission.

A: You will need to run a Check Engine Light s...

You will need to run a Check Engine Light scan. I suspect that you will have a problem with the EGR valve stuck partly open causing the internal vacuum leak and a rough idle. You can remove, clean, and reinstall the valve. If it still leaks then replace the valve.

If you need some help getting this fixed, feel free to contact a certified mechanic who can diagnose your rough idle and make any repairs that are necessary.

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: idles too low and dies, misses while driving

Many different parts can cause the vehicle to start poorly and stall. The most likely are the spark plugs and wires, fuel pump, distributor, or a vacuum leak. If you want to have this checked, a certified mechanic, such as...

Q: Airflow changes when I step on gas pedal

The AC has a vacuum reservoir that is designed to hold a vacuum to the AC blend doors during acceleration, or low engine vacuum conditions. If this system is leaking, the system cannot hold vacuum to the AC, and will...

Q: Will a bad crankshaft position sensor cause my car to turn off while at a stop light?

Hi there. The issue could be one of the following. Check The fuel pressure could be low or dropping when the engine is stalling out - possible fuel pump failure The crankshaft position sensor could be shorting out or...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...
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.